[Federal Register Volume 72, Number 152 (Wednesday, August 8, 2007)]
[Rules and Regulations]
[Pages 44656-44669]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-14937]



[[Page 44655]]

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Part III





Department of Transportation





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Federal Aviation Administration



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14 CFR Part 25



Airplane Performance and Handling Qualities in Icing Conditions; Final 
Rule

  Federal Register / Vol. 72 , No. 152 / Wednesday, August 8, 2007 / 
Rules and Regulations  

[[Page 44656]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2005-22840; Amendment No. 25-121]
RIN 2120-AI14


Airplane Performance and Handling Qualities in Icing Conditions

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: This action introduces new airworthiness standards to evaluate 
the performance and handling characteristics of transport category 
airplanes in icing conditions. This action will improve the level of 
safety for new airplane designs when operating in icing conditions, and 
harmonizes the U.S. and European airworthiness standards for flight in 
icing conditions.

DATES: This final rule becomes effective October 9, 2007.

FOR FURTHER INFORMATION CONTACT: Don Stimson, FAA, Airplane & Flight 
Crew Interface Branch, ANM-111, Transport Airplane Directorate, 
Aircraft Certification Service, 1601 Lind Avenue SW., Renton, 
Washington 98057-3356; telephone: (425) 227-1129; fax: (425) 227-1149, 
e-mail: [email protected].

SUPPLEMENTARY INFORMATION: 

Availability of Rulemaking Documents

    You can get an electronic copy using the Internet by:
    (1) Searching the Department of Transportation's electronic Docket 
Management System (DMS) Web page (http://dms.dot.gov/search);
    (2) Visiting the FAA's Regulations and Policies Web page at http://www.faa.gov/regulations_policies; or
    (3) Accessing the Government Printing Office's Web page at http://www.gpoaccess.gov/fr/index.html.
    You can also get a copy by sending a request to the Federal 
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence 
Avenue SW., Washington, DC 20591, or by calling (202) 267-9680. Make 
sure to identify the docket number or amendment number of this 
rulemaking.
    Anyone is able to search the electronic form of all comments 
received into any of our dockets by the name of the individual 
submitting the comment (or signing the comment, if submitted on behalf 
of an association, business, labor union, etc.). You may review DOT's 
complete Privacy Act statement in the Federal Register published on 
April 11, 2000 (Volume 65, Number 70; Pages 19477-78) or you may visit 
http://dms.dot.gov.

Small Business Regulatory Enforcement Fairness Act

    The Small Business Regulatory Enforcement Fairness Act (SBREFA) of 
1996 requires the FAA to comply with small entity requests for 
information or advice about compliance with statutes and regulations 
within its jurisdiction. If you are a small entity and you have a 
question regarding this document, you may contact a local FAA official, 
or the person listed under FOR FURTHER INFORMATION CONTACT. You can 
find out more about SBREFA on the Internet at http://www.faa.gov/regulations_policies/rulemaking/sbre_act/.

Authority for This Rulemaking

    The FAA's authority to issue rules regarding aviation safety is 
found in Title 49 of the United States Code. Subtitle I, Section 106 
describes the authority of the FAA Administrator. Subtitle VII, 
Aviation Programs, describes in more detail the scope of the agency's 
authority.
    This rulemaking is promulgated under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, the FAA is charged with promoting 
safe flight of civil aircraft in air commerce by prescribing minimum 
standards required in the interest of safety for the design and 
performance of aircraft. This regulation is within the scope of that 
authority because it prescribes new safety standards for the design of 
transport category airplanes.

I. Background

A. Statement of the Problem

    Currently, Sec.  25.1419, ``Ice protection,'' requires transport 
category airplanes with approved ice protection features be capable of 
operating safely within the icing conditions identified in appendix C 
of part 25. This section requires applicants to perform flight testing 
and conduct analyses to make this determination. Section 25.1419 only 
requires an applicant to demonstrate that the airplane can operate 
safely in icing conditions if the applicant is seeking to certificate 
ice protection features.
    Although an airplane's performance capability and handling 
qualities are important in determining whether an airplane can operate 
safely, part 25 does not have specific requirements on airplane 
performance or handling qualities for flight in icing conditions. In 
addition, the FAA does not have a standard set of criteria defining 
what airplane performance capability and handling qualities are needed 
to be able to operate safely in icing conditions. Finally, Sec.  
25.1419 fails to address certification approval for flight in icing 
conditions for airplanes without ice protection features.
    Service history shows that flight in icing conditions may be a 
safety risk for transport category airplanes. We found nine accidents 
since 1983 in the National Transportation Safety Board's accident 
database that may have been prevented if this rule had been in effect. 
In evaluating the potential for this rulemaking to avoid future 
accidents, we considered only past accidents involving tailplane stall 
or potential airframe ice accretion effects on drag or controllability. 
We did not consider accidents related to ground deicing since this 
amendment does not change the ground deicing requirements. We also 
limited our search to accidents involving aircraft certificated to the 
icing standards of part 25 (or its predecessor).

B. NTSB Recommendations

    This amendment addresses the following National Transportation 
Safety Board (NTSB) safety recommendations related to airframe 
icing:\1\
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    \1\ Refer to appendix 3 of the NPRM for more details on these 
safety recommendations (except for A-96-056, which was not discussed 
in the NPRM).
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    1. NTSB Safety Recommendation A-91-087 \2\ recommended requiring 
flight tests where ice is accumulated in those cruise and approach flap 
configurations in which extensive exposure to icing conditions can be 
expected, and requiring subsequent changes in configuration to include 
landing flaps. This safety recommendation resulted from an accident 
that was attributed to tailplane stall due to ice contamination.
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    \2\ ``Effect of Ice on Aircraft Handling Characteristics (1984 
Trials),'' Jetstream 31--G-JSSD, British Aerospace Flight Test 
Report FTR.177/JM, dated May 13, 1985.
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    This amendment requires applicants to investigate the 
susceptibility of airplanes to ice-contaminated tailplane stall during 
airworthiness certification. An accompanying Advisory Circular (AC) 
will provide detailed guidance on acceptable means of compliance, 
including flight tests in icing conditions where the airplane's 
configuration is changed from flaps and landing gear retracted to flaps 
and landing gear in the landing position.

[[Page 44657]]

    2. NTSB Safety Recommendation A-96-056 \3\ recommended revising the 
icing certification testing regulation to ensure that airplanes are 
properly tested for all conditions in which they are authorized to 
operate, or are otherwise shown to be capable of safe flight into such 
conditions. Additionally, if safe operations cannot be demonstrated by 
the manufacturer, operational limitations should be imposed to prohibit 
flight in such conditions and flightcrews should be provided with the 
means to positively determine when they are in icing conditions that 
exceed the limits for aircraft certification.
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    \3\ National Transportation Safety Board, 1996. ``In-Flight 
Icing Encounter and Loss of Control, Simmons Airlines, 
d.b.a.American Eagle Flight 4184, Avions de Transport Regional (ATR) 
Model 72-212, N401AM, Roselawn, Indiana, October 31, 1994.'' 
Aircraft Accident Report NTSB/AAR-96/01. Washington, DC.
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    This amendment partially addresses safety recommendation A-96-056 
by revising the certification standards to ensure that transport 
category airplanes are properly tested for the critical icing 
conditions defined in appendix C of part 25. We are considering future 
rulemaking action to address icing conditions beyond those covered by 
appendix C of part 25, and to provide flightcrews with a means to 
positively determine when they are in icing conditions that exceed the 
limits for aircraft certification.
    3. NTSB Safety Recommendation A-98-094 \4\ recommended that 
manufacturers of all turbine-engine driven airplanes (including the 
EMB-120) provide minimum maneuvering airspeed information for all 
airplane configurations, phases, and conditions of flight (icing and 
non-icing conditions). Also, the NTSB recommended that minimum 
airspeeds should take into consideration the effects of various types, 
amounts, and locations of ice accumulations, including thin amounts of 
very rough ice, ice accumulated in supercooled large droplet icing 
conditions, and tailplane icing.
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    \4\ National Transportation Safety Board, 1998. ``In-Flight 
Icing Encounter and Uncontrolled Collision With Terrain, Comair 
Flight 3272, Embraer EMB-120RT, N265CA, Monroe, Michigan, January 9, 
1997.'' Aircraft Accident Report NTSB/AR-98/04. Washington, DC.
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    This amendment partially addresses safety recommendation A-98-094 
by requiring the same maneuvering capability requirements at the 
minimum operating speeds in the most critical icing conditions defined 
in appendix C of part 25 as are currently required in non-icing 
conditions. We are considering future rulemaking action to address 
supercooled large droplet icing conditions.
    4. NTSB Safety Recommendation A-98-096 is also a result of the same 
accident discussed under Safety Recommendation A-98-094, above. The 
NTSB recommended the FAA require, during type certification, that 
manufacturers and operators of all transport category airplanes 
certificated to operate in icing conditions install stall warning/
protection systems that provide a cockpit warning (aural warning and/or 
stick shaker) before the onset of stall when the airplane is operating 
in icing conditions.
    This amendment requires adequate stall warning margin to be shown 
with the most critical ice accretion for transport category airplanes 
approved to fly in icing conditions. Except for the short time before 
icing conditions are recognized and the ice protection system 
activated, this stall warning must be provided by the same means as for 
non-icing conditions. Although neither an aural stall warning or stick 
shaker is required under this amendment, all recently certificated 
transport category airplanes have used either a stick shaker or an 
aural warning to warn the pilot of an impending stall. We do not 
anticipate any future transport category airplane designs without a 
cockpit warning of an impending stall.

C. Summary of the NPRM

    This amendment is based on the notice of proposed rulemaking 
(NPRM), Notice No. 05-10, which was published in the Federal Register 
on November 4, 2005 (70 FR 67278). In the NPRM, we proposed to revise 
the airworthiness standards for type certification of transport 
category airplanes to add a comprehensive set of new requirements for 
airplane performance and handling qualities for flight in icing 
conditions. We also proposed to add requirements that define the ice 
accretion (that is, the size, shape, location, and texture of the ice) 
that must be considered for each phase of flight.
    These changes were proposed to ensure that minimum operating speeds 
determined during certification of all future transport category 
airplanes will provide adequate maneuver capability in icing conditions 
for all phases of flight and all airplane configurations. They would 
also harmonize the FAA's regulations with those expected to be adopted 
by the European Aviation Safety Agency (EASA). This harmonization would 
not only benefit the aviation industry economically, but also maintain 
the necessary high level of aviation safety.

II. Discussion of the Final Rule

A. General Summary

    Twelve commenters responded to the NPRM: Four private citizens, 
Airbus Industrie (Airbus), the Air Line Pilots Association (ALPA), The 
Boeing Company (Boeing), Dassault Aviation (Dassault), the General 
Aviation Manufacturers Association (GAMA), the National Transportation 
Safety Board (NTSB), Raytheon Aircraft Company (Raytheon), and the 
United Kingdom Civil Aviation Authority (U.K. CAA).
    Seven of these commenters explicitly expressed support for the 
rule, none opposed it. Many of the commenters suggested specific 
improvements or clarifications. Summaries of their comments and our 
responses (including explanations of changes to the final rule in 
response to the comments) are provided below.\5\
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    \5\ The full text of each commenter's submission is available in 
the Docket.
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1. Engine Bleed Configuration for Showing Compliance With Sec.  25.119
    The proposed Sec.  25.119 would require applicants to comply with 
the landing climb performance requirements in both icing and non-icing 
conditions. Raytheon stated that proposed Sec.  25.119(b) is unclear as 
to whether the engine bleed configuration for showing compliance should 
include bleed extraction for operation of the airframe and engine ice 
protection systems (IPS). Raytheon pointed out that engine bleed 
extraction for operating the airframe and engine IPS could affect 
engine acceleration time, which would affect the thrust level used for 
showing compliance. Raytheon noted that the means of compliance in the 
proposed AC addresses this issue, but recommended that it be clarified 
within the rule.
    While we agree that engine bleed extraction could affect the thrust 
level used to show compliance with Sec.  25.119(b), we disagree that 
the rule needs to be revised to state the bleed configuration. For 
flight in icing conditions, Sec.  25.21(g)(1) requires compliance to be 
shown assuming normal operation of the airplane and its IPS in 
accordance with the operating limitations and operating procedures 
established by the applicant and provided in the Airplane Flight Manual 
(AFM). The bleed configuration of the engines would be part of the AFM 
operating procedures that must be used to show compliance with Sec.  
25.119(b). As noted by Raytheon, the guidance provided in the AC 
accompanying this final rule reminds applicants that the

[[Page 44658]]

engine bleed configuration should be considered when showing compliance 
with the requirements of this final rule.
2. Using the Landing Ice Accretion To Comply With Sec.  
25.121(d)(2)(ii)
    Boeing proposed using the landing ice accretion for showing 
compliance with the approach climb gradient requirement in icing 
conditions, rather than the holding ice accretion as proposed in Sec.  
25.121(d)(2)(ii). Boeing recommended this change to harmonize with 
EASA's proposed rule.
    We consider it inappropriate to use the landing ice accretion for 
compliance with Sec.  25.121(d). Section 25.121(d) specifies the 
minimum climb capability, in terms of a climb gradient, that an 
airplane must be capable of achieving in the approach configuration 
with one engine inoperative. This requirement involves the approach 
phase of flight, which occurs before entering the landing phase. 
Depending on the IPS design and the procedures for its use, the landing 
ice accretion (which is defined as the ice accretion after exiting the 
holding phase and transitioning to the landing phase) may be smaller 
than the holding ice accretion. For example, there may be a procedure 
to use the IPS to remove the ice when transitioning to the landing 
phase so that the protected areas are clear of ice for landing. It 
would be inappropriate to allow any reduction in the ice accretion to 
be used for the approach climb gradient (in the approach phase) 
resulting from using the IPS in the landing phase.
    We note that neither EASA's Notice of Proposed Amendment (NPA) 
covering the same icing-related safety issues (NPA 16/2004) nor our 
NPRM define an ice accretion specific to the approach phase of flight. 
Both proposals used holding ice for compliance in icing conditions 
because holding ice was considered to be conservative for this flight 
phase. Therefore, we believe that it is appropriate to define an 
additional ice accretion that would be specifically targeted at the 
approach phase of flight. We have added the following definition as 
paragraph (a)(5) in part II of appendix C:
    ``Approach ice is the critical ice accretion on the unprotected 
parts of the airplane, and any ice accretion on the protected parts 
appropriate to normal IPS operation following exit from the holding 
flight phase and transition to the most critical approach 
configuration.''
    Section 25.121(d)(2)(ii) is also revised to refer to this 
definition. The definition of landing ice is revised to be the ice 
accretion after exiting from the approach phase (rather than after the 
holding phase as proposed) and redesignated as paragraph (a)(6).
    Finally, applicants would still have the option to use a more 
conservative ice accretion in accordance with paragraph (b) of part II 
of appendix C. Therefore, applicants would have the option of using the 
holding ice accretion as proposed in the NPRM if it was more critical 
than the approach ice accretion.
3. VREF Comparison at Maximum Landing Weight
    Proposed Sec.  25.125(a)(2) would require landing distances to be 
determined in icing conditions if the landing approach speed, 
VREF, for icing conditions exceeds VREF for non-
icing conditions by more than 5 knots calibrated airspeed. Boeing 
proposed that the VREF speed comparison for icing and non-
icing conditions in proposed Sec.  25.125(a)(2) be made at the maximum 
landing weight. This proposal would harmonize the FAA's rule with the 
expected EASA final rule. Boeing also stated that the proposed rule was 
deficient in that it did not specify the weight or weights at which 
this comparison must be made. The results of this comparison can depend 
on the weight at which the comparison is made.
    We agree that this comparison should be made at the maximum landing 
weight and have revised Sec.  25.125(a)(2) of the final rule 
accordingly. We consider this to be a clarifying change that will not 
impose an additional burden on applicants.
4. Landing Distance in Icing Conditions
    As noted in the discussion of the previous comment, proposed Sec.  
25.125(a)(2) would require the landing distance to be determined in 
icing conditions if the landing approach speed, VREF, for 
icing conditions exceeds the non-icing VREF by more than 5 
knots calibrated airspeed. An increase in VREF for icing 
conditions is normally caused by an increase in stall speed in icing 
conditions because VREF must be at least 1.23 times the 
stall speed.
    Raytheon noted that a change in stall speed is not the only factor 
that might affect landing distance in icing conditions. For example, 
idle thrust might be adjusted by an engine control system designed to 
maintain sufficient bleed flow to support the demands of engine and 
airframe ice protection. Also, landing procedures for icing conditions 
might be different than for non-icing conditions. Raytheon suggested 
revising proposed Sec.  25.125(a)(2) to require that the landing 
distance must also be determined in icing conditions if the thrust 
settings or landing procedures used in icing conditions would cause an 
increase in the landing distance.
    One of the primary safety concerns addressed by proposed Sec.  
25.125 is to maintain a minimum speed margin above the stall speed for 
an approach and landing in icing conditions. This is achieved by 
increasing the landing approach speed (VREF) if ice on the 
airplane results in a significant increase in stall speed. Under 
proposed Sec.  25.125(b)(2)(ii)(B), a significant increase in stall 
speed relative to this requirement is one that results in an increase 
in VREF of more than 5 knots calibrated airspeed, where 
VREF is not less than 1.23 times the stall speed.
    An increase in VREF will increase the distance required 
by the airplane to land and come to a stop since the airplane will 
touch down at a higher speed. A significant increase in stall speed in 
the landing configuration due to ice has a secondary effect of 
increasing the required landing distance. We proposed in Sec.  
25.125(a)(2) that this increase in landing distance be taken into 
account. Proposed Sec.  25.125(a)(2) resulted from the secondary effect 
of a significant increase in stall speed in the landing configuration 
due to ice, not to an evaluation of all of the possible reasons why the 
required landing distance may need to be longer in icing conditions. 
The commenter correctly points out that a longer landing distance may 
also be needed if higher thrust settings or different landing 
procedures are used in icing conditions.
    In evaluating the potential costs and effects of the proposed 
change, we could not find any existing airplanes where, if the 
requirement proposed by the commenter had been in effect, it would have 
required an applicant to determine a longer landing distance in icing 
conditions. In nearly all cases, applicants have not used different 
thrust or power settings or different procedures for landing in icing 
conditions. Airplane manufacturers indicated that they did not 
anticipate this relationship to change for future designs.
    When different thrust or power settings or procedures have been 
used for landing in icing conditions, VREF has also 
increased by more than 5 knots. In these cases, applicants would be 
required by the proposed Sec.  25.125(a) to determine the landing 
distance for icing conditions, and existing Sec.  25.101(c) and (f) 
require applicants to include the effects of different power or thrust 
settings or landing procedures on this landing distance.

[[Page 44659]]

    Therefore, we see no need to amend the proposed requirement as 
recommended by Raytheon.
5. Sandpaper Ice Accretion
    Proposed appendix C, part II(a)(6) defined sandpaper ice as a thin, 
rough layer of ice. A private citizen notes the NPRM did not 
specifically state how sandpaper ice should be used or considered in 
showing compliance with any of the proposed airplane performance and 
handling qualities requirements. This commenter suggested amending 
proposed Sec.  25.143(i)(1) to add that if normal operation of the 
horizontal tail IPS allows ice to form on the tail leading edge, 
sandpaper ice must also be considered in determining the critical ice 
accretion. (Proposed Sec.  25.143(i)(1) would require applicants to 
demonstrate the airplane is safely controllable, per the applicable 
requirements of Sec.  25.143, with the ice accretion defined in 
appendix C that is most critical for the particular flight phase.)
    Appendix C, part II(a) requires applicants to use the most critical 
ice accretion to show compliance with the applicable subpart B airplane 
performance and handling requirements in icing conditions. The 
determination of the most critical ice accretion must consider the full 
range of atmospheric icing conditions of part I of appendix C as well 
as the characteristics of the IPS (per Sec.  25.21(g)(1) and appendix 
C, part II(a)). This includes consideration of thin, rough layers of 
ice (known as sandpaper ice) as well as any other type of ice accretion 
that may occur in the applicable atmospheric icing conditions, taking 
into account the operating characteristics of the IPS and the flight 
phase.
    Since the requirement to use the most critical ice accretion 
includes consideration of sandpaper ice and sandpaper ice is not 
referenced elsewhere in the rule, we have removed appendix C, part 
II(a)(6) from the final rule. The AC that we are issuing along with 
this final rule, or shortly thereafter, provides further information on 
the use of sandpaper ice in showing compliance. (This AC will be 
available in the Regulatory Guidance Library (RGL) when issued.)
6. Critical Ice Accretion for Showing Compliance With Sec.  
25.143(i)(1)
    As noted in the discussion of the previous comment, proposed Sec.  
25.143(i)(1) would require applicants to demonstrate the airplane is 
safely controllable, per the applicable requirements of Sec.  25.143, 
with the ice accretion defined in appendix C that is most critical for 
the particular flight phase. Raytheon stated that because ice accretion 
before normal system operation is addressed separately in Sec.  
25.143(j), the controllability demonstration required by Sec.  
25.143(i)(1) should be limited to only the most critical ice accretion 
defined in appendix C part II(a) rather than all of appendix C.
    For purposes of the controllability demonstrations required by 
Sec.  25.143(i)(1), appendix C, parts I and II(a), (b), (c), and (d) 
apply. Appendix C, part II(e) only applies to Sec. Sec.  25.143(j) and 
25.207(h), which are the only subpart B requirements pertaining to 
flight in icing conditions before activation of the IPS. We acknowledge 
that this limited applicability of appendix C, part II(e) is unclear in 
the language proposed, and we have revised the final rule to include a 
sentence that specifies this limitation.
7. Pushover Maneuver for Ice-Contaminated Tailplane Stall Evaluation
    Raytheon stated that proposed Sec.  25.143(i)(2), which states that 
a push force from the pilot must be required throughout a pushover 
maneuver down to zero g or full down elevator, is inconsistent with 
allowing a pull force for recovery from the maneuver. Raytheon noted 
that the FAA stated in the NPRM that a force reversal (that is, a push 
force becoming a pull force) is unacceptable, implying that the pilot 
should only be permitted to relax his or her push force to initiate 
recovery. The 50-pound limit for recovery in the proposed Sec.  
25.143(i)(2) appears to allow up to 50 pounds of force reversal to 
develop during the maneuver, including at the initiation of recovery 
from the maneuver. Raytheon stated that they object to the proposed 
requirement and continue to support the industry proposal for the 
pushover maneuver submitted to ARAC by the Flight Test Harmonization 
Working Group. The industry proposal specified there must be no force 
reversal down to 0.5 g (the limit of the operational flight envelope) 
and a prompt recovery from zero g (or full down elevator control if 
zero g cannot be obtained) with less than 50 pounds of stick force. 
Raytheon stated that the 50-pound pull force was not intended as a 
limit for the subsequent pull-up maneuver during recovery from the 
push-over test.
    The FAA continues to disagree with the industry proposal, and 
Raytheon did not offer any new evidence or rationale that would lead us 
to reconsider our position. As stated in the NPRM, certification 
testing and service experience have shown that testing to only 0.5 g is 
inadequate, considering the relatively high frequency of experiencing 
0.5 g in operations. Since the beginning of the 1980s, the practice of 
many certification authorities has been to require testing to lower 
load factors. The industry proposal for determining the acceptability 
of a control force reversal (as described in the NPRM) was subjective 
and would have led to inconsistent evaluations. Requiring a push force 
to zero g removes subjectivity in the assessment of the airplane's 
controllability and provides readily understood criteria of 
acceptability. Any lesser standard would not give confidence that the 
problem has been fully addressed.
    We do not consider the requirement for a push force to be needed to 
reach zero g, coupled with allowing a pull force of up to 50 pounds 
during the recovery, to be inconsistent with our position that force 
reversals are unacceptable within the normal flight envelope. The 
pushover maneuver ends when zero g is reached (or when full down 
elevator is achieved if zero g cannot be reached). The recovery is a 
separate pull-up maneuver, initiated by the pilot, to regain the 
original flight path. It is acceptable for this maneuver to require a 
pull force, but the pull force must not exceed 50 pounds, which is the 
maximum pitch force permitted by the existing Sec.  25.143(c) 
(renumbered as Sec.  25.143(d) by this amendment) for short term 
application of force using one hand. No changes were made.
8. Pushover Maneuver Limited by Design Features Other Than Elevator 
Power
    Airbus noted that proposed Sec.  25.143(i)(2) would allow the 
required pushover maneuver to end before zero g is reached if the 
airplane is limited by elevator power. Airbus commented that safe 
design characteristics other than limited elevator power may also 
prevent an aircraft from reaching zero g during the pushover maneuver 
(e.g., flight envelope protections designed into fly-by-wire control 
systems). Airbus proposed revising the proposed rule to allow the 
pushover maneuver to end before reaching zero g for other safe design 
characteristics that prevent reaching zero g.
    We agree with Airbus and have revised Sec.  25.143(i)(2) to include 
consideration of other design characteristics of the flight control 
system that may prevent reaching zero g in the pushover maneuver.

[[Page 44660]]

9. Pitch Force Requirements During a Sideslip Maneuver
    Raytheon stated that the proposed requirement for flight in icing 
conditions is more stringent than the requirements applicable to non-
icing conditions. Proposed Sec.  25.143(i)(3) would require that any 
changes in force that the pilot must apply to the pitch control to 
maintain speed with increasing sideslip angle must be steadily 
increasing with no force reversals. Raytheon notes the non-icing 
subpart B static lateral-directional stability requirements of Sec.  
25.177 do not specify that the pitch forces cannot reverse. For 
example, a push force at small sideslip angles that changes to a pull 
force as sideslip increases is acceptable.
    Raytheon noted that it would not be unusual for an airplane to 
require an increase in pull force with increasing sideslip. If the 
tailplane or a portion of it developed aerodynamic separation as 
sideslip increases, then to maintain 1-g flight the elevator hinge 
moment would require further pull force that could be sudden or become 
excessive. Raytheon notes this undesirable characteristic would comply 
with proposed Sec.  25.143(i)(3).
    Raytheon and another commenter (a private citizen) proposed that 
the proposed rule be revised to eliminate the requirements that the 
pitch force be steadily increasing with increasing sideslip and that 
there be no reversal. Instead, these commenters suggested that the 
requirement should be limited to ensuring that there is no abrupt or 
uncontrollable pitching tendency.
    The FAA agrees with the commenters that small, gradual changes in 
the pitch control force may not be objectionable or unsafe, and that 
the proposed requirement is unnecessarily more stringent than the 
requirements for non-icing conditions. The safety concern is sudden or 
large pitch force changes that would be difficult for the pilot to 
control. Therefore, we have changed Sec.  25.143(i)(3) in the final 
rule to read as follows:
    ``Any changes in force that the pilot must apply to the pitch 
control to maintain speed with increasing sideslip angle must be 
steadily increasing with no force reversals, unless the change in 
control force is gradual and easily controllable by the pilot without 
using exceptional piloting skill, alertness, or strength.''
    Under this new language, abrupt changes in the control force 
characteristic, unless so small as to be unnoticeable, would not be 
considered to meet the requirement that the force be steadily 
increasing. A gradual change in control force is a change that is not 
abrupt and does not have a steep gradient. It can be easily managed by 
a pilot of average skill, alertness, and strength. Control forces in 
excess of those permitted by Sec.  25.143(d) would be considered 
excessive.
10. Stall Warning in Icing Conditions
    Existing Sec.  25.207(c) requires at least a 3 knot or 3% speed 
margin between the stall warning speed (VSW) and the 
reference stall speed (VSR). Existing Sec.  25.207(d) 
requires at least a 5 knot or 5% speed margin between VSW 
and the speed at which the behavior of the airplane gives the pilot a 
clear and distinctive indication of an acceptable nature that the 
airplane is stalled. Under proposed Sec.  25.21(g), the stall warning 
requirements of Sec.  25.207(c) and (d) would apply only to non-icing 
conditions. For icing conditions, proposed Sec.  25.207(e) requires 
that stall warning be sufficient to allow the pilot to prevent stalling 
when the pilot starts the recovery maneuver not less than 3 seconds 
after the onset of stall warning in a one knot per second deceleration.
    The U.K. CAA noted that proposed Sec.  25.207(e) would allow stall 
warning in icing conditions to occur at a speed slower than the speed 
for the maximum lift capability of the wing (also known as the 1g stall 
speed). This would not be true for non-icing conditions because of 
Sec.  25.207(c). According to U.K. CAA, if the stall warning speed is 
slower than the 1g stall speed, the airplane will have little or no 
maneuvering capability at the point that the airplane gives the pilot a 
warning of an impending stall. The U.K. CAA stated that in an 
operational scenario, if the airplane slows to a speed slightly above 
the stall warning speed, any attempt to maneuver the airplane or 
further reduce speed could lead to an immediate stall. This situation 
is of most concern to the U.K. CAA in the landing phase because, unlike 
the cruise or takeoff phases, there are limited options for the crew to 
recover from a stall. The airplane is already at low altitude and 
descending towards the ground, the power setting is low, and the 
potential to trade height for speed is extremely limited.
    Due to this concern, the U.K. CAA recommended making the non-icing 
stall warning speed margin requirements of Sec.  25.207(c) and (d) also 
apply to icing conditions, but only when the airplane is in the landing 
configuration. Since the proposed Sec.  25.207(e) was intended to be 
used in place of Sec.  25.207(c) and (d) for icing conditions, the U.K. 
CAA suggested that, if Sec.  25.207(c) and (d) are applied to the 
landing configuration in icing conditions, then Sec.  25.207(e) need 
not be applied to the landing configuration.
    In developing the proposed rule, the FAA accepted a determination 
by the Flight Test Harmonization Working Group (FTHWG) that the same 
handling qualities standards should generally apply to flight in icing 
conditions as apply to flight in non-icing conditions. In certain 
areas, however, the FTHWG decided that the handling qualities standards 
for non-icing conditions were inappropriate for flight in icing 
conditions. In these areas, the FTHWG recommended alternative criteria 
for flight in icing conditions.
    The stall warning margin was one of the areas where the FTHWG 
recommended alternative criteria for flight in icing conditions. The 
FTHWG determined that applying the existing stall warning margin 
requirements of Sec.  25.207(c) and (d) to icing conditions would be 
far more stringent than the best current practices and would unduly 
penalize designs that have not exhibited safety problems in icing 
conditions. The FTHWG further determined the stall warning requirements 
of the existing Sec.  25.207(c) and (d) could be made less stringent 
for icing conditions without compromising safety. As a result, we 
proposed the less stringent Sec.  25.207(e) to address stall warning 
margin requirements for icing conditions in place of Sec.  25.207(c) 
and (d).
    No changes have been made to this final rule as a result of the 
U.K. CAA's comment. We acknowledge that the U.K. CAA has pointed out a 
deficiency with safety implications in the proposed stall warning 
requirements. However, U.S. manufacturers' initial cost analysis of the 
U.K. CAA's recommended changes indicates these changes may 
significantly increase the costs of this rulemaking beyond the benefits 
provided due to uncertainties in how the increased stall warning margin 
requirement would affect airplane type certification testing, 
certification program schedules, and the design of stall warning 
systems.
    In addition, the U.K. CAA's recommended changes would introduce 
significant regulatory differences from EASA's airworthiness 
certification requirements, and might not completely resolve the 
potential safety issue. For these reasons we believe that additional 
time and aviation industry participation are needed to determine an 
appropriate way to address this safety concern. However, we do not 
believe it is appropriate to delay issuance of this final rule pending 
resolution of this issue.

[[Page 44661]]

    This final rule significantly improves the affected airworthiness 
standards and the benefits of these improvements should be achieved as 
soon as possible. It also satisfies a number of important NTSB 
recommendations. As these improvements are being implemented, we will 
continue to work closely with EASA and industry to address the issue 
raised by the U.K. CAA. This subject has been included on EASA's 2008 
rulemaking agenda, and we will work with them in that context to agree 
on a harmonized approach. Once these efforts are completed, we will 
initiate new rulemaking, if appropriate, to adopt any necessary 
revisions to part 25.
11. Stall and Stall Warning Requirements Prior to Activation of the IPS
    Proposed Sec.  25.207(h)(2)(ii) would require compliance with the 
stall characteristics requirements of Sec.  25.203, using the stall 
demonstration prescribed by Sec.  25.201, for flight in icing 
conditions before the IPS is activated. This requirement would apply if 
the stall warning required by Sec.  25.207 is provided by a different 
means for flight in icing conditions than for non-icing conditions. The 
stall demonstration prescribed by Sec.  25.201 requires that the 
stalling maneuver be continued to the point where the airplane gives 
the pilot a clear and distinctive indication of an acceptable nature 
that the airplane is stalled.
    Raytheon disagreed with this proposal because the ice accretion 
resulting from a delay in activating the IPS is a short term transient 
condition. According to Raytheon, the intent should be to demonstrate 
only the ability to prevent a stall, rather than to also ensure that 
the airplane has good stall characteristics. Raytheon stated that it is 
unnecessary to consider that the pilot might ignore the stall buffeting 
and continue to increase angle-of-attack until the airplane is stalled. 
To comply with the proposed rule, Raytheon argued that an airplane with 
a stick pusher stall identification system would be required to have 
its stick pusher activation based on a contaminated wing leading edge 
for non-icing conditions. This would require increased takeoff and 
landing speeds and negatively impact all takeoff and landing 
performance.
    Raytheon also stated that the cost impacts would be excessive for 
what is only a transient condition. Raytheon's position is that there 
is no need to consider the airplane's handling qualities after it has 
stalled. It should be sufficient to show that the pilot can prevent 
stalling if the recovery maneuver is not begun until at least three 
seconds after the onset of stall warning, which is also required by the 
proposed Sec.  25.207(h)(2)(ii).
    We do not agree with Raytheon's comments. Because of human factors 
considerations, proposed Sec.  25.207(b) generally requires that the 
same means of providing a stall warning be used in both icing and non-
icing conditions. Therefore, if a stick shaker is used for stall 
warning in non-icing conditions (as is the case for most transport 
category airplanes) it must also be used for stall warning in icing 
conditions. The reason for this proposed requirement is that in icing 
accidents and incidents where the airplane stalled before the stick 
shaker activated, flightcrews have not recognized the buffeting 
associated with ice contamination in time to prevent stalling. Proposed 
Sec.  25.207(h)(2)(ii) allows a different means of providing stall 
warning in icing conditions only for the relatively short time period 
between when the airplane first enters icing conditions and when the 
IPS is activated. (This exception to the proposed Sec.  25.207(b) is 
further limited such that it only applies when the procedures for 
activating the IPS do not involve waiting until a certain amount of ice 
has been accumulated.)
    Because there is still a safety concern with flightcrews 
recognizing a stall warning that is provided by a different means than 
the flightcrew would normally experience, we consider it essential that 
the airplane also be shown to have safe stall characteristics. Poor 
stalling characteristics with an iced wing have directly contributed to 
the severity of icing accidents involving a stall in icing conditions.
    As for Raytheon's comment about the cost impacts, we evaluated 
these as part of the regulatory evaluation conducted for the NPRM, and 
we do not agree that the cost impacts associated with this requirement 
are excessive. In addition, the adopted Sec.  25.207 will not require 
airplanes with stick pusher stall identification systems to have their 
stick pusher activation based on a contaminated wing leading edge for 
non-icing conditions. Section 25.207(h)(2)(ii) does not apply if the 
same stall warning means is used for non-icing and icing conditions. If 
a stick shaker is used for stall warning and if the stick shaker 
activation point must be advanced due to the effect of the ice accreted 
before activation of the IPS, this would result in the same negative 
effect on takeoff and landing speeds. However, if the procedures for 
activating the IPS ensure that it is activated before any ice accretes 
on the wings, neither the stick shaker activation point nor the takeoff 
and landing speeds will be affected. This could be accomplished, for 
example, by using an ice detector that would activate the IPS before 
ice accretes on the wings, or by procedures for activating the IPS 
based on environmental conditions conducive to icing, but before ice 
would actually accrete on the wings.
12. Dissipation of Ice Shapes at High Altitudes and High Mach Numbers
    Proposed Sec.  25.253(c) specifies the maximum speed for 
demonstrating stability characteristics in icing conditions. Proposed 
Sec.  25.253(c)(3) allows this speed to be limited to the speed at 
which it is demonstrated that the airframe will be free of ice 
accretion due to the effects of increased dynamic pressure. Raytheon 
stated that experience has shown that ice shapes dissipate quickly at 
high altitude and high Mach numbers. Raytheon suggested revising Sec.  
25.253(c)(3) to specify the altitude and/or Mach number range that ice 
shapes would dissipate.
    Although we agree that past experience shows that ice shapes 
dissipate or detach at high altitude and high Mach numbers, the 
applicable range may vary with airplane type. The particular conditions 
under which the ice accretions dissipate or detach should be justified 
as part of the certification program. Since this is consistent with 
proposed Sec.  25.253(c), we made no changes to the final rule.
13. Critical Ice Shapes
    Proposed appendix C, part II(a) defines how to determine the 
critical ice accretions for each phase of flight. The NTSB commented 
that for each phase of flight, the applicant should be required to 
demonstrate that the shape, chordwise and spanwise, and the roughness 
of the shapes accurately reflect the full range of appendix C 
conditions in terms of mean effective drop diameter, liquid water 
content, and temperature during each phase of flight. Additionally, the 
NTSB suggested that we review the justification and selection of the 
most critical ice shape for each phase of flight.
    Although we believe the proposed requirements already address the 
NTSB's concerns, we have revised appendix C, part II(a) for additional 
clarity. We added text to state that applicants must demonstrate that 
the full range of atmospheric icing conditions specified in part I of 
appendix C have been considered, including the mean effective drop 
diameter, liquid water content, and

[[Page 44662]]

temperature appropriate to the flight conditions.
14. Takeoff Ice Accretions
    ALPA noted that the takeoff ice accretions defined in proposed 
appendix C, part II(a)(2) do not include the entire takeoff flight 
path. As defined in Sec.  25.111, the takeoff flight path ends at 
either 1,500 feet above the takeoff surface, or the height at which the 
transition from the takeoff to the en route configuration is completed 
and the final takeoff speed (VFTO) is reached, whichever is 
higher. The takeoff flight path in proposed appendix C, part II(a)(2) 
ends at 1,500 feet above the takeoff surface. ALPA stated that there 
are many mountainous airport locations where the takeoff configuration 
must be maintained above 1,500 feet above the takeoff surface for 
terrain clearance at maximum takeoff gross weights. Since winter 
operations in these locations often involve icing conditions, ALPA 
requested that the takeoff flight path of Appendix C, part II(a)(2) be 
revised to match that of Sec.  25.111.
    ALPA's comment points out an oversight in the text of the proposal. 
Appendix C, part II(a)(2) has been revised to include the entire 
takeoff flight path as defined in Sec.  25.111. We consider this to be 
a technical clarification that does not impose a significant additional 
burden on applicants.
15. Size of Ice Accretion Before Activation of the IPS
    For the pre-activation ice identified in Appendix C, part II(e), 
ALPA did not support the 30-second time period for the flightcrew to 
see and respond to ice accreting on the airplane as stated in 
paragraphs 2c(4)(a) and (b) of Appendix 1, Airframe Ice Accretion, of 
proposed AC 25.21-1X. ALPA believes that the ice accreted during a more 
operationally realistic timeframe and the potential degradations in 
aircraft performance and handling qualities must be accounted for 
during certification in order to make the proposed requirements and 
acceptable means of compliance an effective combination. While a well 
designed human factors study could determine an appropriate time, ALPA 
proposed that at least the 2-minute time period contained in 14 CFR 
33.77, Foreign object ingestion--ice, be used as the time to visually 
recognize ice is accreting until definitive studies can be completed.
    The FAA believes that ALPA has misunderstood the use of the 30-
second time period in the proposed AC 25.21-1X acceptable means of 
compliance. The FAA does not expect the flightcrew to see and respond 
to ice accumulating on the airplane within 30 seconds. In accordance 
with Sec.  25.21(g), compliance must be shown using ice accretions 
consistent with the AFM operating procedures. First, applicants must 
determine the ice accretion that would be on the airplane when the AFM 
procedures call for activating the IPS. Then, the 30-second time period 
is used in combination with the continuous maximum icing environment, 
as defined in appendix C of part 25, as a standard for determining the 
additional ice that could accrete on the airplane before the pilot 
actually activates the IPS. Since the appendix C maximum continuous 
icing envelope represents at least the 99th percentile of encounters 
with continuous maximum icing (that is, 99% of the time, less icing 
would occur), it would take significantly longer than 30 seconds in 
nearly all actual icing events for the airplane to accrete this much 
ice.
    As a result of this comment, the FAA reviewed the proposed AC 
25.21-1X text. Although the use of a-30 second time period in a 
continuous maximum icing environment is clearly stated, the FAA 
believes that the text is incomplete regarding what we expect 
applicants to consider in determining the ice accretion specified by 
the AFM procedures for activating the IPS. The FAA is revising the 
proposed AC to state that this ice accretion should be easily 
recognizable by the pilot under all foreseeable conditions (for 
example, at night in clouds). No changes have been made to the 
regulatory requirements.
16. Maximum Size of the Critical Ice Accretion
    Dassault noted that, in Europe, the critical ice accretion is 
limited to a maximum thickness of 3 inches. Dassault did not find such 
a limitation in the NPRM, nor in the proposed advisory circular (AC) 
25.21-1X related to the NPRM. Dassault noted that this omission could 
result in carrying out performance and handling tests with unrealistic 
ice accretions (particularly those assumed to build up on the 
unprotected parts of the airplane during the 45-minute holding flight 
phase referenced in ACs 25.21-X and 25.1419-1A).
    We did not make any changes to the final rule because several 
existing ACs provide guidance for the size of the most critical ice 
accretions that should be considered. This longstanding guidance 
considers a 45-minute holding condition within an icing cloud. Since 
this guidance is not regulatory, we have accepted applicants' use of 
service history and other experience with other compliance criteria to 
determine the maximum ice accretion that needs to be considered. We 
will continue to address this issue in the same manner. The AC being 
issued along with this final rule refers to these alternative methods 
of compliance and provides guidance for their use.
17. Detection of Icing Conditions
    A private citizen commented that icing conditions should be 
monitored by more than the pilot's eyesight. We are unable to address 
the commenter's issue in this rulemaking because this rulemaking only 
addresses performance and handling qualities requirements for the 
current methods of ice detection (which include detection by visual 
means). However, we are pursuing separate rulemaking for future 
airplane designs relative to allowable methods for detecting icing and 
determining when to activate the IPS. In NPRM 07-07, ``Activation of 
Ice Protection,'' published in the Federal Register on April 26, 2007, 
we proposed to amend the airworthiness standards applicable to 
transport category airplanes to require a means to ensure timely 
activation of the airframe IPS.
18. Delayed Activation of the IPS
    ALPA recommended modifying all rule language to eliminate 
references and rule provisions for waiting until a finite amount of ice 
has accumulated before activating the IPS. ALPA stated that delayed 
activation of the IPS has been a factor in several accidents and 
incidents. ALPA also pointed out that the FAA has adopted 17 
airworthiness directives requiring immediate activation of IPS at the 
first sign of ice accretion for a number of airplane types where the 
previous practice was to wait until a specified amount of ice had 
accumulated on the airplane. ALPA noted that after an exhaustive review 
of accident and incident data, ARAC recommended an operating rule that 
would remove the option of delaying activation of the IPS.
    Except for the airworthiness directives referenced by ALPA, current 
regulations do not prohibit AFM procedures that call for delaying 
activation of the IPS until a specified amount of ice has accreted. 
Although we strongly encourage activating the IPS at the first sign of 
ice accretion, there may be some designs for which delayed activation 
is currently acceptable, safe, and appropriate. For example, some 
thermal wing IPS can currently be used in either an anti-ice or deice 
mode. In the deice mode, the wing IPS is not activated until a certain 
amount of ice

[[Page 44663]]

has accreted. This has not resulted in any safety issues, and can be a 
more economical way of operating the wing IPS.
    The purpose of this rulemaking is to provide appropriate 
performance and handling qualities requirements, considering the 
currently accepted procedures for activating the IPS. Establishing new 
requirements for acceptable methods for activating the IPS is beyond 
the scope of this rulemaking. As ALPA noted, however, ARAC has 
recommended the FAA adopt new requirements that would ensure 
flightcrews are provided with a clear means to know when to activate 
the IPS in a timely manner. We are pursuing separate rulemaking in 
response to this ARAC recommendation. In NPRM 07-07, ``Activation of 
Ice Protection,'' published in the Federal Register on April 26, 2007, 
we proposed to amend the airworthiness standards applicable to 
transport category airplanes to require a means to ensure timely 
activation of the airframe IPS. We will update the requirements adopted 
by this final rule related to the means of activating the IPS, if 
necessary, to be consistent with any final action resulting from NPRM 
07-07, ``Activation of Ice Protection.''
19. Harmonization With EASA's NPA
    Several commenters noted that the FAA did not fully harmonize the 
NPRM with the EASA's NPA covering the same icing-related safety issues. 
They recommended harmonizing the two rule proposals.
    We worked closely with EASA to ensure that there are no significant 
regulatory differences between this amendment and EASA's anticipated 
final rule. However, since EASA's final rule has not yet been issued, 
we cannot guarantee that the two final rules will be completely 
harmonized. We believe that any differences will be primarily editorial 
and not significant regulatory differences.
20. Accuracy of the Regulatory Flexibility Evaluation
    GAMA requested that the FAA review the regulatory flexibility 
evaluation in the interest of accuracy.
    We reviewed the regulatory flexibility evaluation and reaffirmed 
the determination that this proposed rule would not have a significant 
economic impact on a substantial number of small entities. All U.S. 
part 25 aircraft manufacturers exceed the Small Business Administration 
small-entity criteria of 1,500 employees for aircraft manufacturers.
21. Aircraft Population Used When Determining Cost Versus Benefit
    GAMA stated that it appeared the cost proposal considered U.S. 
manufactured aircraft while the benefit section included international 
products. GAMA believes that the same aircraft population should be 
used when determining cost versus benefit. Additionally, GAMA stated 
that it appeared it was assumed that cost was only attributed to 
entirely new TC products. GAMA believes it would be appropriate to 
consider the economic impact to some amount of amended TC and STC 
projects as well.
    Section 1 of Executive Order 12866 states ``Federal agencies should 
promulgate only such regulations as are required by law, are necessary 
to interpret the law, or are made necessary by compelling public need, 
such as material failures of private markets to protect or improve the 
health and safety of the public, the environment, or the well-being of 
the American people.'' Section 5 states ``In order to reduce the 
regulatory burden on the American people, their families, their 
communities, their State, local, and tribal governments and their 
industries * * *.'' Therefore, regulatory evaluations and flexibility 
analyses focus on American people and American industries.
    American industries, such as manufacturers and operators of 
aircraft, must comply with regulations promulgated by Federal agencies. 
Foreign firms are not required to comply with U.S. regulations unless 
they choose to sell or operate their aircraft in America.
    We determined the costs for this proposal by analyzing only 
American manufacturing industries, since foreign firms are not required 
to comply with U.S. regulations unless they choose to sell or operate 
their aircraft in America. While we do consider foreign manufactured 
aircraft in the benefit section, we determined the benefits by 
analyzing only American operators of those aircraft. Hence, the intent 
of Executive Order 12866 was satisfied.
    We did include amended TCs in the analysis. Each TC includes all 
derivatives for a particular aircraft model. For example, TC No. A16WE 
initially covered only the Boeing 737-100, but was later amended to 
include the -200 through -900 Boeing 737 models.
    Future applicants for approval of changed products are subject to 
Sec.  21.101 (Changed Product Rule). There are several provisions of 
Sec.  21.101 allowing future applicants of changed products to comply 
with earlier regulation amendments. We have already determined that 
benefits of the Changed Product Rule exceed the costs. Therefore, we do 
not estimate the benefits and costs of changed products for new 
certification rules.
22. Value of Fatalities Avoided
    A private citizen claimed that the value of the fatalities avoided 
by this proposal would be in the neighborhood of $20 billion.
    The number of averted fatalities and injuries is based on the 
historical accident rate extrapolated into the future. The FAA used 
$3.0 million for an avoided fatality and $132,700 for the additional 
associated medical and legal costs' for a fatality. The derivation for 
these values is discussed in the ``Economic Values for FAA Investment 
and Regulatory Decisions, A Guide.'' \6\ Without the rule, we expect 
that over the 45-year analysis period, approximately three accidents 
will occur. These three accidents are expected to result in 
approximately 12 fatalities, six serious injuries, and two minor 
injuries. From these values, and expected future accidents based on 
past accident history, we estimated a benefit of about $90 million over 
the 45-year analysis period.
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III. Rulemaking Analyses and Notices

Paperwork Reduction Act

    There are no current or new requirements for information collection 
associated with this amendment.

International Compatibility

    In keeping with U.S. obligations under the Convention on 
International Civil Aviation, it is FAA policy to comply with 
International Civil Aviation Organization (ICAO) Standards and 
Recommended Practices to the maximum extent practicable. The FAA has 
determined that there are no ICAO Standards and Recommended Practices 
that correspond to these regulations.

Economic Assessment, Regulatory Flexibility Determination, Trade Impact 
Assessment, and Unfunded Mandates Assessment

    Changes to Federal regulations must undergo several economic 
analyses. First, Executive Order 12866 directs each Federal agency to 
propose or adopt a regulation only upon a reasoned determination that 
the benefits of the intended regulation justify its costs.

[[Page 44664]]

Second, the Regulatory Flexibility Act of 1980 requires agencies to 
analyze the economic impact of regulatory changes on small entities. 
Third, the Trade Agreements Act (19 U.S.C. 2531-2533) prohibits 
agencies from setting standards that create unnecessary obstacles to 
the foreign commerce of the United States. In developing U.S. 
standards, this Trade Act also requires agencies to consider 
international standards and, where appropriate, use them as the basis 
of U.S. standards. Fourth, the Unfunded Mandates Reform Act of 1995 
(Pub. L. 104-4) requires agencies to prepare a written assessment of 
the costs, benefits, and other effects of proposed or final rules that 
include a Federal mandate likely to result in the expenditure by State, 
local, or tribal governments, in the aggregate, or by the private 
sector, of $100 million or more annually (adjusted for inflation with 
the base year of 1995.)
    In conducting these analyses, FAA has determined this rule (1) has 
benefits that justify its costs, is not a ``significant regulatory 
action'' as defined in section 3(f) of Executive Order 12866 and is not 
``significant'' as defined in DOT's Regulatory Policies and Procedures; 
(2) will not have a significant economic impact on a substantial number 
of small entities; (3) will not reduce barriers to international trade; 
and (4) does not impose an unfunded mandate on state, local, or tribal 
governments, or on the private sector. These analyses, available in the 
docket, are summarized below.
Introduction
    This portion of the preamble summarizes the FAA's analysis of the 
economic impacts of a final rule amending part 25 of Title 14, Code of 
Federal Regulations (14 CFR) to change the regulations applicable to 
transport category airplanes certificated for flight in icing 
conditions. It also includes summaries of the regulatory flexibility 
determination, the international trade impact assessment, and the 
unfunded mandates assessment. We suggest readers seeking greater detail 
read the full regulatory evaluation, a copy of which we have placed in 
the docket for this rulemaking.
Total Benefits and Costs of This Rulemaking
    The estimated potential benefits of avoiding 3 accidents over the 
45-year analysis interval are $89.2 million ($23.6 million in present 
value at seven percent). To obtain these benefits, over the 45-year 
analysis interval, manufacturers will incur additional certification 
costs of $9.8 million and the operators of these airplanes will pay 
$52.5 million in additional fuel-burn. We estimate the total cost of 
this final rule to be about $62.3 million and the seven percent present 
value cost of the rule will be about $23.0 million.
Who Is Potentially Affected by This Rulemaking
     Operators of part 25 U.S.-registered aircraft conducting 
operations under FAR Parts 121, 129, and 135, and
     Manufacturers of those part 25 aircraft.
Our Cost Assumptions and Sources of Information
    This evaluation makes the following assumptions:
    1. This final rule is assumed to become effective immediately.
    2. The production runs for newly certificated part 25 airplane 
models is 20 years.
    3. The average life of a part 25 airplane is 25 years.
    4. We analyzed the costs and benefits of this final rule over the 
45-year period (20 + 25 = 45) 2006 through 2050.
    5. We used a 10-year certification compliance period. For the 10-
year life-cycle period, the FAA calculated an average of four new 
certifications will occur.
    6. We used $3.0 million as the value of an avoided fatality.
    7. New airplane certifications will occur in year one of the 
analysis time period.
Benefits of This Rulemaking
    The benefits of this final rule consist of the value of lives saved 
due to avoiding three accidents involving part 25 airplanes operating 
in icing conditions. Based on the historic accident rate, we estimate 
that a total of 12 fatalities could potentially be avoided by adopting 
the final rule. Over the 45-year period of analysis, the potential 
benefit of the propose rule will be $89.2 million ($23.6 million in 
present value at seven percent).
Costs of This Rulemaking
    We estimate the costs of this final rule to be about $62.3 million 
($23.0 million in present value at seven percent) over the 45-year 
analysis period. The total cost of $62.3 million equals the fixed 
certification costs of $9.8 million incurred in the first year plus the 
variable annual fuel burn cost of $52.5 million over the 45-year 
analysis period.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (Pub. L. 96-354) (RFA) 
establishes ``as a principle of regulatory issuance that agencies shall 
endeavor, consistent with the objectives of the rule and of applicable 
statutes, to fit regulatory and informational requirements to the scale 
of the businesses, organizations, and governmental jurisdictions 
subject to regulation. To achieve this principle, agencies are required 
to solicit and consider flexible regulatory proposals and to explain 
the rationale for their actions to assure that such proposals are given 
serious consideration.'' The RFA covers a wide-range of small entities, 
including small businesses, not-for-profit organizations, and small 
governmental jurisdictions.
    Agencies must perform a review to determine whether a rule will 
have a significant economic impact on a substantial number of small 
entities. If the agency determines that it will, the agency must 
prepare a regulatory flexibility analysis as described in the RFA.
    However, if an agency determines that a rule is not expected to 
have a significant economic impact on a substantial number of small 
entities, section 605(b) of the RFA provides that the head of the 
agency may so certify and a regulatory flexibility analysis is not 
required. The certification must include a statement providing the 
factual basis for this determination, and the reasoning should be 
clear.
    In the interest of accuracy, one commenter requested we review the 
determination we made in the proposed rules regulatory flexibility 
evaluation. We reviewed the determination from the proposed rule and 
came to the same conclusions for this final rule for the reasons 
discussed below.
    Currently U.S. manufactured part 25 aircraft type certificate 
holders include: The Boeing Company, Cessna Aircraft Company (a 
subsidiary of Textron Inc.), Raytheon Company, and Gulfstream Aerospace 
Corporation (a wholly owned subsidiary of General Dynamics). All United 
States part 25 aircraft manufacturers exceed the Small Business 
Administration small-entity criteria of 1,500 employees for aircraft 
manufacturers.
    This rule will add an additional weighted average monthly fuel burn 
cost of about $42 per airplane, which is less than an hour of fuel burn 
and thus a minimal additional cost to all operators.
    Given that manufacturers are not small entities and operators incur 
a minimal additional cost, as the FAA Administrator, I certify that 
this final rule will not have a significant economic impact on a 
substantial number of small entities.

[[Page 44665]]

International Trade Impact Assessment

    The Trade Agreements Act of 1979 (Pub. L. 96-39) prohibits Federal 
agencies from establishing any standards or engaging in related 
activities that create unnecessary obstacles to the foreign commerce of 
the United States. Legitimate domestic objectives, such as safety, are 
not considered unnecessary obstacles. The statute also requires 
consideration of international standards and, where appropriate, that 
they be the basis for U.S. standards. The FAA has assessed the 
potential effect of this final rule and determined that it will impose 
the same costs on domestic and international entities and thus has a 
neutral trade impact.

Unfunded Mandates Assessment

    Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-
4) requires each Federal agency to prepare a written statement 
assessing the effects of any Federal mandate in a proposed or final 
agency rule that may result in an expenditure of $100 million or more 
(adjusted annually for inflation with the base year 1995) in any one 
year by State, local, and tribal governments, in the aggregate, or by 
the private sector; such a mandate is deemed to be a ``significant 
regulatory action.'' The FAA currently uses an inflation-adjusted value 
of $128.1 million in lieu of $100 million.
    This final rule does not contain such a mandate. The requirements 
of Title II do not apply.

Executive Order 13132, Federalism

    The FAA has analyzed this final rule under the principles and 
criteria of Executive Order 13132, Federalism. We determined that this 
action will not have a substantial direct effect on the States, or the 
relationship between the national Government and the States, or on the 
distribution of power and responsibilities among the various levels of 
government, and therefore does not have federalism implications.

Regulations Affecting Intrastate Aviation in Alaska

    Section 1205 of the FAA Reauthorization Act of 1996 (110 Stat. 
3213) requires the FAA, when modifying its regulations in a manner 
affecting intrastate aviation in Alaska, to consider the extent to 
which Alaska is not served by transportation modes other than aviation, 
and to establish appropriate regulatory distinctions. In the NPRM, we 
requested comments on whether the proposed rule should apply 
differently to intrastate operations in Alaska. We didn't receive any 
comments, and we have determined, based on the administrative record of 
this rulemaking, that there is no need to make any regulatory 
distinctions applicable to intrastate aviation in Alaska.

Environmental Analysis

    FAA Order 1050.1E identifies FAA actions that are categorically 
excluded from preparation of an environmental assessment or 
environmental impact statement under the National Environmental Policy 
Act in the absence of extraordinary circumstances. The FAA has 
determined this rulemaking action qualifies for the categorical 
exclusion identified in paragraph 312f and involves no extraordinary 
circumstances.

Regulations That Significantly Affect Energy Supply, Distribution, or 
Use

    The FAA has analyzed this final rule under Executive Order 13211, 
Actions Concerning Regulations that Significantly Affect Energy Supply, 
Distribution, or Use (May 18, 2001). We have determined that it is not 
a ``significant energy action,'' and it is not likely to have a 
significant adverse effect on the supply, distribution, or use of 
energy.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

The Amendment

0
In consideration of the foregoing, the Federal Aviation Administration 
amends part 25 of Title 14, Code of Federal Regulations, as follows:

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

0
1. The authority citation for part 25 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, and 44704.


0
2. Amend Sec.  25.21 by adding a new paragraph (g) to read as follows:


Sec.  25.21  Proof of compliance.

* * * * *
    (g) The requirements of this subpart associated with icing 
conditions apply only if the applicant is seeking certification for 
flight in icing conditions.
    (1) Each requirement of this subpart, except Sec. Sec.  25.121(a), 
25.123(c), 25.143(b)(1) and (b)(2), 25.149, 25.201(c)(2), 25.207(c) and 
(d), 25.239, and 25.251(b) through (e), must be met in icing 
conditions. Compliance must be shown using the ice accretions defined 
in appendix C, assuming normal operation of the airplane and its ice 
protection system in accordance with the operating limitations and 
operating procedures established by the applicant and provided in the 
Airplane Flight Manual.
    (2) No changes in the load distribution limits of Sec.  25.23, the 
weight limits of Sec.  25.25 (except where limited by performance 
requirements of this subpart), and the center of gravity limits of 
Sec.  25.27, from those for non-icing conditions, are allowed for 
flight in icing conditions or with ice accretion.


0
3. Amend Sec.  25.103 by revising paragraph (b)(3) to read as follows:


Sec.  25.103  Stall speed.

* * * * *
    (b) * * *
    (3) The airplane in other respects (such as flaps, landing gear, 
and ice accretions) in the condition existing in the test or 
performance standard in which VSR is being used;
* * * * *


0
4. Amend Sec.  25.105 by revising paragraph (a) to read as follows:


Sec.  25.105  Takeoff.

    (a) The takeoff speeds prescribed by Sec.  25.107, the accelerate-
stop distance prescribed by Sec.  25.109, the takeoff path prescribed 
by Sec.  25.111, the takeoff distance and takeoff run prescribed by 
Sec.  25.113, and the net takeoff flight path prescribed by Sec.  
25.115, must be determined in the selected configuration for takeoff at 
each weight, altitude, and ambient temperature within the operational 
limits selected by the applicant--
    (1) In non-icing conditions; and
    (2) In icing conditions, if in the configuration of Sec.  25.121(b) 
with the takeoff ice accretion defined in appendix C:
    (i) The stall speed at maximum takeoff weight exceeds that in non-
icing conditions by more than the greater of 3 knots CAS or 3 percent 
of VSR; or
    (ii) The degradation of the gradient of climb determined in 
accordance with Sec.  25.121(b) is greater than one-half of the 
applicable actual-to-net takeoff flight path gradient reduction defined 
in Sec.  25.115(b).
* * * * *

0
5. Amend Sec.  25.107 by revising paragraph (c)(3) and (g)(2) and 
adding new paragraph (h) to read as follows:


Sec.  25.107  Takeoff speeds.

* * * * *
    (c) * * *

[[Page 44666]]

    (3) A speed that provides the maneuvering capability specified in 
Sec.  25.143(h).
* * * * *
    (g) * * *
    (2) A speed that provides the maneuvering capability specified in 
Sec.  25.143(h).
    (h) In determining the takeoff speeds V1, VR, 
and V2 for flight in icing conditions, the values of 
VMCG, VMC, and VMU determined for non-
icing conditions may be used.

0
6. Amend Sec.  25.111 by revising paragraph (c)(3)(iii), (c)(4), and 
adding a new paragraph (c)(5) to read as follows:


Sec.  25.111  Takeoff path.

* * * * *
    (c) * * *
    (3) * * *
    (iii) 1.7 percent for four-engine airplanes.
    (4) The airplane configuration may not be changed, except for gear 
retraction and automatic propeller feathering, and no change in power 
or thrust that requires action by the pilot may be made until the 
airplane is 400 feet above the takeoff surface; and
    (5) If Sec.  25.105(a)(2) requires the takeoff path to be 
determined for flight in icing conditions, the airborne part of the 
takeoff must be based on the airplane drag:
    (i) With the takeoff ice accretion defined in appendix C, from a 
height of 35 feet above the takeoff surface up to the point where the 
airplane is 400 feet above the takeoff surface; and
    (ii) With the final takeoff ice accretion defined in appendix C, 
from the point where the airplane is 400 feet above the takeoff surface 
to the end of the takeoff path.
* * * * *

0
7. Revise Sec.  25.119 to read as follows:


Sec.  25.119  Landing climb: All-engines-operating.

    In the landing configuration, the steady gradient of climb may not 
be less than 3.2 percent, with the engines at the power or thrust that 
is available 8 seconds after initiation of movement of the power or 
thrust controls from the minimum flight idle to the go-around power or 
thrust setting--
    (a) In non-icing conditions, with a climb speed of VREF 
determined in accordance with Sec.  25.125(b)(2)(i); and
    (b) In icing conditions with the landing ice accretion defined in 
appendix C, and with a climb speed of VREF determined in 
accordance with Sec.  25.125(b)(2)(ii).

0
8. Amend Sec.  25.121 by revising paragraphs (b), (c), and (d) to read 
as follows:


Sec.  25.121  Climb: One-engine inoperative.

* * * * *
    (b) Takeoff; landing gear retracted. In the takeoff configuration 
existing at the point of the flight path at which the landing gear is 
fully retracted, and in the configuration used in Sec.  25.111 but 
without ground effect:
    (1) The steady gradient of climb may not be less than 2.4 percent 
for two-engine airplanes, 2.7 percent for three-engine airplanes, and 
3.0 percent for four-engine airplanes, at V2 with:
    (i) The critical engine inoperative, the remaining engines at the 
takeoff power or thrust available at the time the landing gear is fully 
retracted, determined under Sec.  25.111, unless there is a more 
critical power operating condition existing later along the flight path 
but before the point where the airplane reaches a height of 400 feet 
above the takeoff surface; and
    (ii) The weight equal to the weight existing when the airplane's 
landing gear is fully retracted, determined under Sec.  25.111.
    (2) The requirements of paragraph (b)(1) of this section must be 
met:
    (i) In non-icing conditions; and
    (ii) In icing conditions with the takeoff ice accretion defined in 
appendix C, if in the configuration of Sec.  25.121(b) with the takeoff 
ice accretion:
    (A) The stall speed at maximum takeoff weight exceeds that in non-
icing conditions by more than the greater of 3 knots CAS or 3 percent 
of VSR; or
    (B) The degradation of the gradient of climb determined in 
accordance with Sec.  25.121(b) is greater than one-half of the 
applicable actual-to-net takeoff flight path gradient reduction defined 
in Sec.  25.115(b).
    (c) Final takeoff. In the en route configuration at the end of the 
takeoff path determined in accordance with Sec.  25.111:
    (1) The steady gradient of climb may not be less than 1.2 percent 
for two-engine airplanes, 1.5 percent for three-engine airplanes, and 
1.7 percent for four-engine airplanes, at VFTO with--
    (i) The critical engine inoperative and the remaining engines at 
the available maximum continuous power or thrust; and
    (ii) The weight equal to the weight existing at the end of the 
takeoff path, determined under Sec.  25.111.
    (2) The requirements of paragraph (c)(1) of this section must be 
met:
    (i) In non-icing conditions; and
    (ii) In icing conditions with the final takeoff ice accretion 
defined in appendix C, if in the configuration of Sec.  25.121(b) with 
the takeoff ice accretion:
    (A) The stall speed at maximum takeoff weight exceeds that in non-
icing conditions by more than the greater of 3 knots CAS or 3 percent 
of VSR; or
    (B) The degradation of the gradient of climb determined in 
accordance with Sec.  25.121(b) is greater than one-half of the 
applicable actual-to-net takeoff flight path gradient reduction defined 
in Sec.  25.115(b).
    (d) Approach. In a configuration corresponding to the normal all-
engines-operating procedure in which VSR for this 
configuration does not exceed 110 percent of the VSR for the 
related all-engines-operating landing configuration:
    (1) The steady gradient of climb may not be less than 2.1 percent 
for two-engine airplanes, 2.4 percent for three-engine airplanes, and 
2.7 percent for four-engine airplanes, with--
    (i) The critical engine inoperative, the remaining engines at the 
go-around power or thrust setting;
    (ii) The maximum landing weight;
    (iii) A climb speed established in connection with normal landing 
procedures, but not exceeding 1.4 VSR; and
    (iv) Landing gear retracted.
    (2) The requirements of paragraph (d)(1) of this section must be 
met:
    (i) In non-icing conditions; and
    (ii) In icing conditions with the approach ice accretion defined in 
appendix C. The climb speed selected for non-icing conditions may be 
used if the climb speed for icing conditions, computed in accordance 
with paragraph (d)(1)(iii) of this section, does not exceed that for 
non-icing conditions by more than the greater of 3 knots CAS or 3 
percent.

0
9. Amend Sec.  25.123 by revising paragraph (a) introductory text and 
paragraph (b) to read as follows:


Sec.  25.123  En route flight paths.

    (a) For the en route configuration, the flight paths prescribed in 
paragraph (b) and (c) of this section must be determined at each 
weight, altitude, and ambient temperature, within the operating limits 
established for the airplane. The variation of weight along the flight 
path, accounting for the progressive consumption of fuel and oil by the 
operating engines, may be included in the computation. The flight paths 
must be determined at a speed not less than VFTO, with--
    * * *
    (b) The one-engine-inoperative net flight path data must represent 
the actual climb performance diminished by a gradient of climb of 1.1 
percent for two-engine airplanes, 1.4 percent for three-engine 
airplanes, and 1.6 percent for four-engine airplanes--

[[Page 44667]]

    (1) In non-icing conditions; and
    (2) In icing conditions with the en route ice accretion defined in 
appendix C, if:
    (i) A speed of 1.18 VSR with the en route ice accretion 
exceeds the en route speed selected for non-icing conditions by more 
than the greater of 3 knots CAS or 3 percent of VSR; or
    (ii) The degradation of the gradient of climb is greater than one-
half of the applicable actual-to-net flight path reduction defined in 
paragraph (b) of this section.
* * * * *

0
10. Revise Sec.  25.125 to read as follows:


Sec.  25.125  Landing.

    (a) The horizontal distance necessary to land and to come to a 
complete stop (or to a speed of approximately 3 knots for water 
landings) from a point 50 feet above the landing surface must be 
determined (for standard temperatures, at each weight, altitude, and 
wind within the operational limits established by the applicant for the 
airplane):
    (1) In non-icing conditions; and
    (2) In icing conditions with the landing ice accretion defined in 
appendix C if VREF for icing conditions exceeds 
VREF for non-icing conditions by more than 5 knots CAS at 
the maximum landing weight.
    (b) In determining the distance in paragraph (a) of this section:
    (1) The airplane must be in the landing configuration.
    (2) A stabilized approach, with a calibrated airspeed of not less 
than VREF, must be maintained down to the 50-foot height.
    (i) In non-icing conditions, VREF may not be less than:
    (A) 1.23 VSR0;
    (B) VMCL established under Sec.  25.149(f); and
    (C) A speed that provides the maneuvering capability specified in 
Sec.  25.143(h).
    (ii) In icing conditions, VREF may not be less than:
    (A) The speed determined in paragraph (b)(2)(i) of this section;
    (B) 1.23 VSR0 with the landing ice accretion defined in 
appendix C if that speed exceeds VREF for non-icing 
conditions by more than 5 knots CAS; and
    (C) A speed that provides the maneuvering capability specified in 
Sec.  25.143(h) with the landing ice accretion defined in appendix C.
    (3) Changes in configuration, power or thrust, and speed, must be 
made in accordance with the established procedures for service 
operation.
    (4) The landing must be made without excessive vertical 
acceleration, tendency to bounce, nose over, ground loop, porpoise, or 
water loop.
    (5) The landings may not require exceptional piloting skill or 
alertness.
    (c) For landplanes and amphibians, the landing distance on land 
must be determined on a level, smooth, dry, hard-surfaced runway. In 
addition--
    (1) The pressures on the wheel braking systems may not exceed those 
specified by the brake manufacturer;
    (2) The brakes may not be used so as to cause excessive wear of 
brakes or tires; and
    (3) Means other than wheel brakes may be used if that means--
    (i) Is safe and reliable;
    (ii) Is used so that consistent results can be expected in service; 
and
    (iii) Is such that exceptional skill is not required to control the 
airplane.
    (d) For seaplanes and amphibians, the landing distance on water 
must be determined on smooth water.
    (e) For skiplanes, the landing distance on snow must be determined 
on smooth, dry, snow.
    (f) The landing distance data must include correction factors for 
not more than 50 percent of the nominal wind components along the 
landing path opposite to the direction of landing, and not less than 
150 percent of the nominal wind components along the landing path in 
the direction of landing.
    (g) If any device is used that depends on the operation of any 
engine, and if the landing distance would be noticeably increased when 
a landing is made with that engine inoperative, the landing distance 
must be determined with that engine inoperative unless the use of 
compensating means will result in a landing distance not more than that 
with each engine operating.

0
11. Amend Sec.  25.143 by redesignating paragraphs (c) through (g) as 
paragraphs (d) through (h) respectively; adding a new paragraph (c); 
revising redesignated paragraphs (d), (e), and (f); amending 
redesignated paragraph (h) by removing the words ``Thrust power 
setting'' in the fourth column of the table and replacing them with the 
words ``Thrust/power setting''; and adding paragraphs (i), and (j) to 
read as follows:


Sec.  25.143  General.

* * * * *
    (c) The airplane must be shown to be safely controllable and 
maneuverable with the critical ice accretion appropriate to the phase 
of flight defined in appendix C, and with the critical engine 
inoperative and its propeller (if applicable) in the minimum drag 
position:
    (1) At the minimum V2 for takeoff;
    (2) During an approach and go-around; and
    (3) During an approach and landing.
    (d) The following table prescribes, for conventional wheel type 
controls, the maximum control forces permitted during the testing 
required by paragraph (a) through (c) of this section:

 
------------------------------------------------------------------------
   Force, in pounds, applied to the control
            wheel or rudder pedals              Pitch     Roll     Yaw
------------------------------------------------------------------------
For short term application for pitch and roll       75       50  .......
 control--two hands available for control....
For short term application for pitch and roll       50       25  .......
 control--one hand available for control.....
For short term application for yaw control...  .......  .......      150
For long term application....................       10        5       20
------------------------------------------------------------------------

    (e) Approved operating procedures or conventional operating 
practices must be followed when demonstrating compliance with the 
control force limitations for short term application that are 
prescribed in paragraph (d) of this section. The airplane must be in 
trim, or as near to being in trim as practical, in the preceding steady 
flight condition. For the takeoff condition, the airplane must be 
trimmed according to the approved operating procedures.
    (f) When demonstrating compliance with the control force 
limitations for long term application that are prescribed in paragraph 
(d) of this section, the airplane must be in trim, or as near to being 
in trim as practical.
* * * * *
    (i) When demonstrating compliance with Sec.  25.143 in icing 
conditions--
    (1) Controllability must be demonstrated with the ice accretion 
defined in appendix C that is most critical for the particular flight 
phase;
    (2) It must be shown that a push force is required throughout a 
pushover maneuver down to a zero g load factor, or the lowest load 
factor obtainable if limited by elevator power or other design 
characteristic of the flight control system. It must be possible to 
promptly recover from the maneuver without exceeding a pull control 
force of 50 pounds; and
    (3) Any changes in force that the pilot must apply to the pitch 
control to

[[Page 44668]]

maintain speed with increasing sideslip angle must be steadily 
increasing with no force reversals, unless the change in control force 
is gradual and easily controllable by the pilot without using 
exceptional piloting skill, alertness, or strength.
    (j) For flight in icing conditions before the ice protection system 
has been activated and is performing its intended function, the 
following requirements apply:
    (1) If activating the ice protection system depends on the pilot 
seeing a specified ice accretion on a reference surface (not just the 
first indication of icing), the requirements of Sec.  25.143 apply with 
the ice accretion defined in appendix C, part II(e).
    (2) For other means of activating the ice protection system, it 
must be demonstrated in flight with the ice accretion defined in 
appendix C, part II(e) that:
    (i) The airplane is controllable in a pull-up maneuver up to 1.5 g 
load factor; and
    (ii) There is no pitch control force reversal during a pushover 
maneuver down to 0.5 g load factor.

0
12. Amend Sec.  25.207 by revising paragraph (b); redesignating 
paragraphs (e) and (f) as paragraphs (f) and (g) respectively; adding a 
new paragraph (e); revising redesignated paragraph (f) and adding 
paragraph (h) to read as follows:


Sec.  25.207  Stall warning.

* * * * *
    (b) The warning must be furnished either through the inherent 
aerodynamic qualities of the airplane or by a device that will give 
clearly distinguishable indications under expected conditions of 
flight. However, a visual stall warning device that requires the 
attention of the crew within the cockpit is not acceptable by itself. 
If a warning device is used, it must provide a warning in each of the 
airplane configurations prescribed in paragraph (a) of this section at 
the speed prescribed in paragraphs (c) and (d) of this section. Except 
for the stall warning prescribed in paragraph (h)(2)(ii) of this 
section, the stall warning for flight in icing conditions prescribed in 
paragraph (e) of this section must be provided by the same means as the 
stall warning for flight in non-icing conditions.
* * * * *
    (e) In icing conditions, the stall warning margin in straight and 
turning flight must be sufficient to allow the pilot to prevent 
stalling (as defined in Sec.  25.201(d)) when the pilot starts a 
recovery maneuver not less than three seconds after the onset of stall 
warning. When demonstrating compliance with this paragraph, the pilot 
must perform the recovery maneuver in the same way as for the airplane 
in non-icing conditions. Compliance with this requirement must be 
demonstrated in flight with the speed reduced at rates not exceeding 
one knot per second, with--
    (1) The more critical of the takeoff ice and final takeoff ice 
accretions defined in appendix C for each configuration used in the 
takeoff phase of flight;
    (2) The en route ice accretion defined in appendix C for the en 
route configuration;
    (3) The holding ice accretion defined in appendix C for the holding 
configuration(s);
    (4) The approach ice accretion defined in appendix C for the 
approach configuration(s); and
    (5) The landing ice accretion defined in appendix C for the landing 
and go-around configuration(s).
    (f) The stall warning margin must be sufficient in both non-icing 
and icing conditions to allow the pilot to prevent stalling when the 
pilot starts a recovery maneuver not less than one second after the 
onset of stall warning in slow-down turns with at least 1.5 g load 
factor normal to the flight path and airspeed deceleration rates of at 
least 2 knots per second. When demonstrating compliance with this 
paragraph for icing conditions, the pilot must perform the recovery 
maneuver in the same way as for the airplane in non-icing conditions. 
Compliance with this requirement must be demonstrated in flight with--
    (1) The flaps and landing gear in any normal position;
    (2) The airplane trimmed for straight flight at a speed of 1.3 
VSR; and
    (3) The power or thrust necessary to maintain level flight at 1.3 
VSR.
* * * * *
    (h) For flight in icing conditions before the ice protection system 
has been activated and is performing its intended function, the 
following requirements apply, with the ice accretion defined in 
appendix C, part II(e):
    (1) If activating the ice protection system depends on the pilot 
seeing a specified ice accretion on a reference surface (not just the 
first indication of icing), the requirements of this section apply, 
except for paragraphs (c) and (d) of this section.
    (2) For other means of activating the ice protection system, the 
stall warning margin in straight and turning flight must be sufficient 
to allow the pilot to prevent stalling without encountering any adverse 
flight characteristics when the speed is reduced at rates not exceeding 
one knot per second and the pilot performs the recovery maneuver in the 
same way as for flight in non-icing conditions.
    (i) If stall warning is provided by the same means as for flight in 
non-icing conditions, the pilot may not start the recovery maneuver 
earlier than one second after the onset of stall warning.
    (ii) If stall warning is provided by a different means than for 
flight in non-icing conditions, the pilot may not start the recovery 
maneuver earlier than 3 seconds after the onset of stall warning. Also, 
compliance must be shown with Sec.  25.203 using the demonstration 
prescribed by Sec.  25.201, except that the deceleration rates of Sec.  
25.201(c)(2) need not be demonstrated.

0
13. Amend Sec.  25.237 by revising paragraph (a) to read as follows:


Sec.  25.237  Wind velocities.

    (a) For land planes and amphibians, the following applies:
    (1) A 90-degree cross component of wind velocity, demonstrated to 
be safe for takeoff and landing, must be established for dry runways 
and must be at least 20 knots or 0.2 VSR0, whichever is 
greater, except that it need not exceed 25 knots.
    (2) The crosswind component for takeoff established without ice 
accretions is valid in icing conditions.
    (3) The landing crosswind component must be established for:
    (i) Non-icing conditions, and
    (ii) Icing conditions with the landing ice accretion defined in 
appendix C.
* * * * *

0
14. Amend Sec.  25.253 by revising paragraph (b), and adding a new 
paragraph (c) to read as follows:


Sec.  25.253  High-speed characteristics.

* * * * *
    (b) Maximum speed for stability characteristics. VFC/
MFC. VFC/MFC is the maximum speed at 
which the requirements of Sec. Sec.  25.143(g), 25.147(E), 
25.175(b)(1), 25.177, and 25.181 must be met with flaps and landing 
gear retracted. Except as noted in Sec.  25.253(c), VFC/
MFC may not be less than a speed midway between 
VMO/MMO and VDF/MDF, except 
that for altitudes where Mach number is the limiting factor, 
MFC need not exceed the Mach number at which effective speed 
warning occurs.
    (c) Maximum speed for stability characteristics in icing 
conditions. The maximum speed for stability characteristics with the 
ice accretions defined in appendix C, at which the

[[Page 44669]]

requirements of Sec. Sec.  25.143(g), 25.147(e), 25.175(b)(1), 25.177, 
and 25.181 must be met, is the lower of:
    (1) 300 knots CAS;
    (2) VFC; or
    (3) A speed at which it is demonstrated that the airframe will be 
free of ice accretion due to the effects of increased dynamic pressure.
0
15. Amend Sec.  25.773 by revising paragraph (b)(1)(ii) to read as 
follows:


Sec.  25.773  Pilot compartment view.

* * * * *
    (b) * * *
    (1) * * *
    (i) * * *
    (ii) The icing conditions specified in Sec.  25.1419 if 
certification for flight in icing conditions is requested.
* * * * *

0
16. Amend Sec.  25.941 by revising paragraph (c) to read as follows:


Sec.  25.941  Inlet, engine, and exhaust compatibility.

* * * * *
    (c) In showing compliance with paragraph (b) of this section, the 
pilot strength required may not exceed the limits set forth in Sec.  
25.143(d), subject to the conditions set forth in paragraphs (e) and 
(f) of Sec.  25.143.

0
17. Amend Sec.  25.1419 by revising the introductory text to read as 
follows:


Sec.  25.1419  Ice protection.

    If the applicant seeks certification for flight in icing 
conditions, the airplane must be able to safely operate in the 
continuous maximum and intermittent maximum icing conditions of 
appendix C. To establish this--
* * * * *
0
18. Amend appendix C to part 25 by adding a part I heading and a new 
paragraph (c) to part I; and adding a new part II to read as follows:

Appendix C of Part 25

Part I--Atmospheric Icing Conditions

    (a) * * *
    (c) Takeoff maximum icing. The maximum intensity of atmospheric 
icing conditions for takeoff (takeoff maximum icing) is defined by 
the cloud liquid water content of 0.35 g/m3, the mean effective 
diameter of the cloud droplets of 20 microns, and the ambient air 
temperature at ground level of minus 9 degrees Celsius (-9( C). The 
takeoff maximum icing conditions extend from ground level to a 
height of 1,500 feet above the level of the takeoff surface.

Part II--Airframe Ice Accretions for Showing Compliance With Subpart B.

    (a) Ice accretions--General. The most critical ice accretion in 
terms of airplane performance and handling qualities for each flight 
phase must be used to show compliance with the applicable airplane 
performance and handling requirements in icing conditions of subpart 
B of this part. Applicants must demonstrate that the full range of 
atmospheric icing conditions specified in part I of this appendix 
have been considered, including the mean effective drop diameter, 
liquid water content, and temperature appropriate to the flight 
conditions (for example, configuration, speed, angle-of-attack, and 
altitude). The ice accretions for each flight phase are defined as 
follows:
    (1) Takeoffice is the most critical ice accretion on unprotected 
surfaces and any ice accretion on the protected surfaces appropriate 
to normal ice protection system operation, occurring between liftoff 
and 400 feet above the takeoff surface, assuming accretion starts at 
liftoff in the takeoff maximum icing conditions of part I, paragraph 
(c) of this appendix.
    (2) Final takeoff ice is the most critical ice accretion on 
unprotected surfaces, and any ice accretion on the protected 
surfaces appropriate to normal ice protection system operation, 
between 400 feet and either 1,500 feet above the takeoff surface, or 
the height at which the transition from the takeoff to the en route 
configuration is completed and VFTO is reached, whichever 
is higher. Ice accretion is assumed to start at liftoff in the 
takeoff maximum icing conditions of part I, paragraph (c) of this 
appendix.
    (3) En route ice is the critical ice accretion on the 
unprotected surfaces, and any ice accretion on the protected 
surfaces appropriate to normal ice protection system operation, 
during the en route phase.
    (4) Holding ice is the critical ice accretion on the unprotected 
surfaces, and any ice accretion on the protected surfaces 
appropriate to normal ice protection system operation, during the 
holding flight phase.
    (5) Approach ice is the critical ice accretion on the 
unprotected surfaces, and any ice accretion on the protected 
surfaces appropriate to normal ice protection system operation 
following exit from the holding flight phase and transition to the 
most critical approach configuration.
    (6) Landing ice is the critical ice accretion on the unprotected 
surfaces, and any ice accretion on the protected surfaces 
appropriate to normal ice protection system operation following exit 
from the approach flight phase and transition to the final landing 
configuration.
    (b) In order to reduce the number of ice accretions to be 
considered when demonstrating compliance with the requirements of 
Sec.  25.21(g), any of the ice accretions defined in paragraph (a) 
of this section may be used for any other flight phase if it is 
shown to be more critical than the specific ice accretion defined 
for that flight phase. Configuration differences and their effects 
on ice accretions must be taken into account.
    (c) The ice accretion that has the most adverse effect on 
handling qualities may be used for airplane performance tests 
provided any difference in performance is conservatively taken into 
account.
    (d) For both unprotected and protected parts, the ice accretion 
for the takeoff phase may be determined by calculation, assuming the 
takeoff maximum icing conditions defined in appendix C, and assuming 
that:
    (1) Airfoils, control surfaces and, if applicable, propellers 
are free from frost, snow, or ice at the start of the takeoff;
    (2) The ice accretion starts at liftoff;
    (3) The critical ratio of thrust/power-to-weight;
    (4) Failure of the critical engine occurs at VEF; and
    (5) Crew activation of the ice protection system is in 
accordance with a normal operating procedure provided in the 
Airplane Flight Manual, except that after beginning the takeoff 
roll, it must be assumed that the crew takes no action to activate 
the ice protection system until the airplane is at least 400 feet 
above the takeoff surface.
    (e) The ice accretion before the ice protection system has been 
activated and is performing its intended function is the critical 
ice accretion formed on the unprotected and normally protected 
surfaces before activation and effective operation of the ice 
protection system in continuous maximum atmospheric icing 
conditions. This ice accretion only applies in showing compliance to 
Sec. Sec.  25.143(j) and 25.207(h).

    Issued in Washington, DC, on July 25, 2007.
Marion C. Blakey,
Administrator.
[FR Doc. E7-14937 Filed 8-7-07; 8:45 am]
BILLING CODE 4910-13-P