[Federal Register Volume 61, Number 12 (Thursday, January 18, 1996)]
[Proposed Rules]
[Pages 1260-1268]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-415]




[[Page 1259]]

_______________________________________________________________________

Part II





Department of Transportation





_______________________________________________________________________



Federal Aviation Administration



_______________________________________________________________________



14 CFR Part 1, et al.



1-g Stall Speed as the Basis for Compliance With Part 25 of the Federal 
Aviation Regulations; Proposed Rule

  Federal Register / Vol. 61, No. 12 / Thursday, January 18, 1996 / 
Proposed Rules  

[[Page 1260]]


DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 1, 25, 36, and 97

[Docket No. 28404; Notice No. 95-17]
RIN 2120-AD40


1-g Stall Speed as the Basis for Compliance With Part 25 of the 
Federal Aviation Regulations

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking.

-----------------------------------------------------------------------

SUMMARY: The Federal Aviation Administration (FAA) proposes to redefine 
the reference stall speed for transport category airplanes as the 1-g 
stall speed instead of the minimum speed obtained in a stalling 
maneuver. The proposed changes would: provide for a consistent, 
repeatable reference stall speed; ensure consistent and dependable 
maneuvering margins; provide for adjusted multiplying factors to 
maintain approximately the current requirements in areas where use of 
the minimum speed in the stalling maneuver has proven adequate; and 
harmonize the applicable regulations with those proposed for the 
European Joint Aviation Requirements-25 (JAR-25). These changes would 
result in a higher level of safety for those cases in which current 
methods would result in artificially low operating speeds.

DATES: Comments must be received on or before May 17, 1996.

ADDRESSES: Comments on this notice may be mailed in triplicate to: 
Federal Aviation Administration, Office of the Chief Counsel, 
Attention: Rules Docket (AGC-10), Docket No. 28404, 800 Independence 
Avenue SW., Washington, DC 20591; or delivered in triplicate to: Room 
915G, 800 Independence Avenue SW., Washington, DC 20591. Comments 
delivered must be marked Docket No. 28404. Comments may be examined in 
Room 915G weekdays, except Federal holidays, between 8:30 a.m. and 5:00 
p.m. In addition, the FAA is maintaining an information docket of 
comments in the Transport Airplane Directorate (ANM-100), Federal 
Aviation Administration, Northwest Mountain Region, 1601 Lind Avenue 
SW., Renton, WA 98055-4056. Comments in the information docket may be 
examined weekdays, except Federal holidays, between 7:30 a.m. and 4:00 
p.m.

FOR FURTHER INFORMATION CONTACT: Don Stimson, Flight Test and Systems 
Branch, ANM-111, Transport Airplane Directorate, Aircraft Certification 
Service, FAA, 1601 Lind Avenue SW., Renton, WA 98055-4056; telephone 
(206) 227-1129; facsimile (206) 227-1320.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    Interested persons are invited to participate in this proposed 
rulemaking by submitting such written data, views, or arguments as they 
may desire. Comments relating to any environmental, energy, or economic 
impact that might result from adopting the proposals contained in this 
notice are invited. Substantive comments should be accompanied by cost 
estimates. Commenters should identify the regulatory docket or notice 
number and submit comments in triplicate to the Rules Docket address 
above. All comments received on or before the closing date for comments 
will be considered by the Administrator before taking action on this 
proposed rulemaking. The proposals contained in this notice may be 
changed in light of comments received. All comments received will be 
available in the Rules Docket, both before and after the comment period 
closing date, for examination by interested persons. A report 
summarizing each substantive public contact with FAA personnel 
concerning this rulemaking will be filed in the docket. Persons wishing 
the FAA to acknowledge receipt of their comments must submit with those 
comments a self-addressed, stamped postcard on which the following 
statement is made: ``Comments to Docket No. 28404.'' The postcard will 
be date stamped and returned to the commenter.

Availability of the NPRM

    Any person may obtain a copy of this notice by submitting a request 
to the Federal Aviation Administration, Office of Public Affairs, 
Attention: Public Inquiry Center, APA-230, 800 Independence Avenue SW., 
Washington, DC 20591; or by calling (202) 267-3484. The notice number 
of this NPRM must be identified in all communications. Persons 
interested in being placed on a mailing list for future rulemaking 
documents should also request a copy of Advisory Circular No. 11-2A, 
Notice of Proposed Rulemaking Distribution System, which describes the 
application procedure.

Background

    The stalling speed (V2) is defined as the minimum speed 
demonstrated in the performance stall maneuver described in Sec. 25.103 
of 14 CFR part 25 (part 25) of the Federal Aviation Regulations (FAR). 
VS has historically served as a reference speed for determining 
the minimum operating speeds for transport category airplanes. Examples 
of minimum operating speeds that are based on VS include the 
takeoff safety speed (V2), the final takeoff climb speed, and the 
landing approach speed. The airworthiness standards of part 25 define 
these speeds as multiples of VS. For example, V2 must be at 
least 1.2 times VS, the final takeoff climb speed must be at least 
1.25 times VS, and the landing approach speed must be at least 1.3 
times VS.
    The speed margin, or difference in speed, between VS and each 
minimum operating speed provides a safety ``cushion'' to ensure that 
normal operating speeds are sufficiently higher than the speed at which 
the airplane stalls. Using multiplying factors applied to VS to 
provide this speed margin, however, assumes that VS provides a 
proper reference stall speed. Since VS is the minimum speed 
obtained in the stalling maneuver, it can be less than the lowest speed 
at which the airplane's weight is still supported entirely by 
aerodynamic lift. If VS is significantly less than this speed, 
applying multiplying factors to VS to determine the minimum 
operating speeds may not provide as large a speed margin as intended.
    A proper reference stall speed should provide a reasonably 
consistent approximation of the wing's maximum usable lift. Maximum 
usable lift occurs at the minimum speed for which the lift provided by 
the wing is capable of supporting the weight of the airplane. This 
speed is known as the 1-g stall speed because the load factor (the 
ratio of airplane lift to weight) at this speed is equal to 1.0 ``g'' 
(where ``g'' is the acceleration caused by the force of gravity) in the 
direction perpendicular to the flight path of the airplane. A speed 
lower than the 1-g stall speed represents a transient flight condition 
that, if used as a reference for the deriving minimum operating speeds, 
may not provide the desired speed margin to protect against 
inadvertently stalling the airplane.
    For jet transport airplanes, the minimum speed obtained in the 
stall maneuver of Sec. 25.103 usually occurs near the point in the 
maneuver where the airplane spontaneously pitches nose-down or where 
the pilot initiates recovery after reaching a deterrent level of 
buffet, i.e., a vibration of a magnitude and severity that is a strong 
and effective deterrent to further speed reduction. Early generation 
transport airplanes, which had fairly straight 

[[Page 1261]]
wings, typically pitched nose-down near the 1-g stall speed. The 
minimum speed in the maneuver was easy to note and record, and served 
as an adequate approximation of the speed for maximum lift.
    For the recent generation of high speed transport airplanes with 
swept wings, however, the minimum speed obtained in the stalling 
maneuver can be substantially lower than the speed for maximum lift. 
Furthermore, the point at which the airplane pitches nose down or 
exhibits a deterrent level of buffet is more difficult to distinguish 
and can vary with piloting technique. As a result, the minimum speed in 
the stalling maneuver has become an inappropriate reference for most 
modern high speed transport airplanes for establishing minimum 
operating speeds since it may: (1) Be inconsistently determined, and 
(2) represent a flight condition in which the load factor perpendicular 
to the flight path is substantially less than 1.0 g.
    In recent years, advanced technology transport category airplanes 
have been developed that employ novel flight control systems. These 
flight control systems incorporate unique protection features that are 
intended to prevent the airplane from stalling. They also prevent the 
airplane from maintaining speeds that are slower than a small 
percentage above the 1-g stall speed. Because of their unique design 
features, the traditional method of establishing VS as the minimum 
speed obtained in the stalling maneuver was inappropriate for these 
airplanes. The FAA issued special conditions for these airplanes to 
define the reference stall speed as the 1-g stall speed for the flight 
requirements contained in subpart B of part 25 and the noise 
requirements contained in part 36 of the FAR.
    In these special conditions, the multiplying factors used to 
determine the minimum operating speeds were reduced in order to 
maintain equivalency with acceptable operating speeds used by previous 
jet transports. Since the 1-g stall speed is generally higher than the 
minimum speed obtained in the stalling maneuver, retaining the current 
multiplying factors would have resulted in higher minimum operating 
speeds for airplanes using the 1-g stall speed as the reference stall 
speed. However, increasing the minimum operating speeds would impose 
costs on operators because payloads would have to be reduced to comply 
with the regulations at the higher operating speeds. Based on the 
service experience of the current fleet of jet transports, the costs 
imposed would not be offset by a commensurate increase in safety.
    Several airplane types with conventional flight control systems 
have also been certificated using the 1-g stall speed as the reference 
stall speed. Because of the potential deficiencies in using the minimum 
speed demonstrated in the stalling maneuver, the FAA has been 
encouraging applicants to use the 1-g stall speed in lieu of the 
minimum speed obtained in the stalling maneuver. Applicants generally 
desire to use 1-g stall speeds because the 1-g stall speeds are less 
dependent on pilot technique and other subjective evaluations. Hence, 
1-g stall speeds are easier to predict and provide a higher level of 
confidence for developing predictions of overall airplane performance. 
Again, reduced multiplying factors are applied to the 1-g stall speeds 
to obtain minimum operational service. Using 1-g stall speeds ensures 
that the airplane's minimum operating speeds will not be unreasonably 
low.

Discussion of the Proposals

    The FAA proposes to define the reference stall speed in Sec. 25.103 
as a 1-g stall speed, rather than the minimum speed obtained in the 
stalling maneuver. This action would provide a consistent basis for use 
in all type design certification requirements for transport category 
airplanes. The FAA proposes to introduce the symbol VSR to 
represent this speed and to indicate that it is different than the 
minimum speed obtained in the stalling maneuver, VS.
    In addition, the FAA proposes to reduce the multiplying factors 
that are used in combination with the reference stall speed to 
determine the minimum operating speeds by approximately 6 percent. This 
change would result in minimum operating speeds equivalent to those for 
most current jet transports since the 1-g stall speed for these 
airplanes is approximately 6 percent higher than the minimum speed 
obtained in the stalling maneuver. Demonstrating a minimum stalling 
speed more than 6 percent slower than the 1-g stall speed, which is 
possible under the current standards, would provide an unacceptable 
basis for determining the minimum operating speeds. The proposed 
standards would prevent this situation from occurring. In this respect, 
the proposed standards would provide a higher level of safety than the 
existing standards.
    However, the reduced factors would allow lower minimum operating 
speeds to be established for those airplanes that have a minimum speed 
in the stalling maneuver approximately equal to the 1-g stall speed. 
One particular class of airplanes for which this applies are airplanes 
equipped with devices that abruptly push the nose down (e.g., stick 
pushers) near the angle of attack for maximum lift. These devices are 
typically installed on airplanes with unacceptable natural stalling 
characteristics. The abrupt nose down push provides an artificial stall 
indication and acceptable stall characteristics, and prevents the 
airplane from reaching a potentially hazardous natural aerodynamic 
stall. The minimum speed obtained in this maneuver is approximately 
equal to the 1-g stall speed.
    Traditionally, the existing multiplying factors have been applied 
to these airplanes. The proposal to define the reference stall speed as 
the 1-g stall speed would not affect these airplanes, but reducing the 
multiplying factors would allow lower minimum operating speeds to be 
established. Therefore, this proposal would allow these airplanes to be 
operated at speeds and angles-of-attack closer to the pusher activation 
point than has been experienced in operational service.
    The FAA considers this reduction in operating speeds for pusher-
equipped airplanes to be acceptable, provided the pusher reliably 
performs its intended function and that unwanted operation is 
minimized. The FAA intends to propose an acceptable method of 
addressing these concerns in an upcoming revision to Advisory Circular 
(AC) 25-7. In this material, the FAA will provide criteria for pusher 
reliability, the effects of design and manufacturing tolerances on the 
pusher activation point, design features such as phase advance and 
filtering, and the affects of atmospheric turbulence and windshear.
    In addition to proposing to define the reference stall speed as the 
1-g stall speed and to reduce the multiplying factors for establishing 
the minimum operating speeds, the FAA also proposes to require 
applicants to demonstrate adequate maneuvering capability during the 
takeoff climb, en route climb, and landing approach phases of flight. 
During a banked turn, a portion of the lift generated by the wing 
provides a force to help turn the airplane. To remain at the same 
altitude, the airplane must produce additional lift. Therefore, banking 
the airplane (at a constant speed and altitude) reduces the stall 
margin, which is the difference between the lift required for the 
maneuver and the maximum lift capability of the wing. As the bank angle 
increases, the stall margin is reduced proportionately. This bank angle 
effect on the stall margin can be determined analytically, and the 
multiplying factors applied to VSR to 

[[Page 1262]]
determine the minimum operating speeds are intended to ensure that an 
adequate stall margin is maintained.
    In addition to the basic effect of bank angle, however, modern wing 
designs also typically exhibit a significant reduction in maximum lift 
capability with increasing Mach number. The magnitude of this Mach 
number effect depends on the design characteristics of the particular 
wing. For wing designs with a large Mach number effect, the maximum 
bank angle that can be achieved while retaining an acceptable stall 
margin can be significantly reduced. Because the effect of Mach number 
can be significant, and because it can also vary greatly for different 
wing designs, the multiplying factors applied to VSR are 
insufficient to ensure that adequate maneuvering capability exists at 
the minimum operating speeds.
    To address this issue, the FAA proposes to require a minimum bank 
angle capability in a coordinated turn without encountering stall 
warning or any other characteristic that might interfere with normal 
maneuvering. This requirement would be added to Sec. 25.143 as a new 
paragraph (g). The proposed minimum bank angles were derived by adding 
a 15 degree allowance for wind gusts and inadvertent overshoot to a 
maneuvering capability the FAA considers necessary for the specific 
cases identified in the proposed new paragraph. These proposed maneuver 
margin requirements are intended to ensure that the level of safety in 
maneuvering flight is not reduced by the proposed change to the 
reference stall speed and the reduction in the multiplying factors used 
to determine the minimum operating speeds.
    Consistent with the proposed maneuver margin requirements, the FAA 
proposes adding Secs. 25.107(c)(3), 25.107(g)(2), and 25.125(a)(2)(iii) 
to reference Sec. 25.143(g) in the list of constraints applicants must 
consider when selecting the minimum takeoff safety speed, final takeoff 
speed, and reference landing speeds, respectively. The normal all-
engines-operating takeoff climb speed selected by the applicant must 
also provide the minimum bank angle capability specified in the 
proposed Sec. 25.143(g).
    Section 25.145(a) requires that there be adequate longitudinal 
control available to promptly pitch the airplane's nose down from at or 
near the stall in order to return to original trim speed. The intent of 
this requirement is to ensure sufficient pitch control for a prompt 
recovery if the airplane is inadvertently slowed to the point of stall. 
The FAA proposes to change the wording of this requirement to replace 
``VS'' with ``the stall,'' ``Sec. 25.103(b)(1)'' with 
``Sec. 25.103(a)(6),'' and ``at any speed'' with ``at any point.'' 
These changes would be consistent with the proposed change to the 
definition of the reference stall speed and the proposed re-formatting 
of Sec. 25.103.
    Although Sec. 25.145(a) must be met both with power off and with 
maximum continuous power, there is no intention to require flight test 
demonstrations of full stalls at engine powers above that specified in 
Sec. 25.201(a)(2). Instead of performing a full stall at maximum 
continuous power, compliance may be assessed by demonstrating 
sufficient static longitudinal stability and nose down control margin 
when the deceleration is ended at least one second past stall warning 
during a one knot per second deceleration. The static longitudinal 
stability during the maneuver and the nose down control power remaining 
at the end of the maneuver must be sufficient to assure compliance with 
the requirement.
    Section 25.207 requires that a warning of an impending stall must 
be provided in order to prevent the pilot from inadvertently stalling 
the airplane. The warning must occur at a speed sufficiently higher 
than the stall speed to allow the pilot time to take action to avoid a 
stall. The speed difference between the stall speed and the speed at 
which the stall warning occurs is known as the stall warning margin. 
The FAA proposes amending the size of the stall warning margin required 
by Sec. 25.207(c) because of the change in definition of the reference 
stall speed.
    Currently, the stall warning must begin at a speed exceeding 
VS by seven knots, or a lesser margin if the stall warning has 
enough clarity, duration, distinctiveness, or other similar properties. 
Requiring the same seven knot warning margin to be provided relative to 
VSR would result in an increase to the minimum operating speeds. 
This increase in the minimum operating speeds would be necessary to 
meet the maneuvering margin requirements proposed in Sec. 25.143(g), 
which are defined relative to the stall warning speed. However, as 
discussed previously, requiring an increase to the minimum operating 
speeds would impose costs to airplane operators that cannot be 
justified by service experience.
    On the other hand, if the stall warning margin were reduced to 
retain approximately the same stall warning speed, the warning would 
occur only one or two knots prior to reaching the 1-g stall speed. 
Although reaching the 1-g stall speed is not likely to be a 
catastrophic occurrence, the FAA considers such a small stall warning 
margin to be unacceptable. The FAA proposes requiring a stall warning 
margin of at least 3 knots or 3 percent, whichever is greater, relative 
to VSR. The FAA considers this margin to represent a reasonable 
balance between providing the pilot with enough warning to avert an 
impending stall, and providing adequate maneuvering capability at the 
minimum operating speeds. This proposal would retain the existing level 
of safety.
    The FAA proposes to require a larger stall warning margin for 
airplanes equipped with devices that abruptly push the nose down at a 
selected angle of attack (e.g., stick pushers). Inadvertent operation 
of such a device, especially close to the ground, can have more serious 
consequences than a comparable situation in which the pilot of an 
airplane without the device inadvertently slows to VSR. Therefore, 
the FAA proposes adding Sec. 25.207(d) to require the stall warning, 
for airplanes equipped with one of these devices, to occur at least 5 
knots or 5 percent, whichever is greater, above the speed at which the 
device activates. This proposal is intended to retain the existing 
level of safety for airplanes equipped with such devices.
    The FAA proposes to add a new paragraph, Sec. 25.207(e), to require 
that, in a slow-down turn with load factors up to 1.5 g and 
deceleration rates up to 3 knots per second, sufficient stall warning 
must exist to prevent stalling when recovery is initiated not less than 
one second after stall warning occurs. The FAA considers the proposed 
requirement necessary to provide adequate stall warning during a 
dynamic maneuver, such as a collision avoidance maneuver. In addition, 
this new paragraph would provide a quantitative requirement with which 
to assess whether ``sufficient margin to prevent inadvertent stalling * 
* * in turning flight'' has been provided as required by 
Sec. 25.207(a). This proposal would increase the level of safety during 
maneuvering flight.
    The FAA proposes to add a new paragraph, Sec. 25.207(f), to require 
that stall warning be provided for abnormal airplane configurations 
likely to be used following system failures. This proposal adds a 
requirement currently contained in JAR-25 and is consistent with 
current transport airplane designs. There would be no impact on the 
existing level of safety.
    On modern jet transports, the natural buffet or vibration caused by 
the airflow separating and reattaching itself to the wing as the 
airplane approaches the 

[[Page 1263]]
stall speed is usually not strong enough by itself to provide an 
effective stall warning. Therefore, stall warning on modern transport 
category airplanes is usually provided through an artificial means, 
such as a stick shaker that shakes the pilot's control column. 
Production tolerances associated with these systems can result in 
variations in the size of the stall warning margin for different 
airplanes manufactured under the same approved type design.
    The FAA considers the stall warning margins proposed in 
Secs. 25.207(c) and (d) to be the minimum acceptable warning margins, 
and that these margins should not be reduced by production tolerances 
associated with a system added to the airplane to provide an artificial 
stall warning. The FAA intends for the proposed stall warning margins 
to be available at the most critical tolerance expected in production. 
Applicants would be expected to demonstrate compliance with the 
proposed stall warning margin either by flight testing with the stall 
warning system set to its critical tolerance setting, or by adjusting 
flight test data obtained at some other setting.
    The tolerances associated with the stall warning system must also 
be considered in relation to the proposed minimum maneuvering 
requirements of Sec. 25.143(g). As proposed, Sec. 25.143(g) would 
require that the airplane be capable of reaching a minimum bank angle 
during a coordinated turn without encountering stall warning. Because 
the proposed requirements already provide the capability to overshoot 
the intended bank angle by 15 degrees, the small differences in the 
speed at which the stall warning system operates due to system 
tolerances are not as critical. Therefore, the FAA intends for the 
minimum bank angles in the proposed Sec. 25.143(g) to apply at the 
designed nominal setting of the stall warning system. To ensure that 
large production tolerances do not adversely impact the airplane's 
maneuvering capability free of stall warning, the bank angle capability 
specified in the proposed Sec. 25.143(g) should not be reduced by more 
than two degrees with the stall warning system operating at its most 
critical tolerance. Applicants would be expected to demonstrate this 
capability either by flight test with the system set to its critical 
tolerance, or by analytically adjusting flight test data obtained at 
some other setting.
    To be consistent with the proposed revision of the definition of 
the reference stall speed, the FAA proposes to incorporate reduced 
multiplying factors throughout part 25, where appropriate, in 
requirements that use speeds based on a multiple of the reference stall 
speed. The FAA also proposes numerous minor wording and structural 
changes to various sections to improve editorial clarity and to 
harmonize with the wording and structure proposed for JAR-25.
    The FAA proposes to add the nomenclature ``final takeoff speed'' 
and ``reference landing speed'' and the abbreviations ``VFTO'' and 
``VREF'' to denote these speeds, respectively, to part 1 of the 
FAR. These terms and abbreviations, which are commonly used in the 
aviation industry, would be referenced throughout the proposed 
amendments to part 25. The reference landing speed would be defined as 
the speed of the airplane, in a specified landing configuration, at the 
point where it descends through the landing screen height in the 
determination of the landing distance for manual landings. The term 
``landing screen height'' refers to the height of the airplane at the 
beginning of the defined landing distance. This height is normally 50 
feet above the landing surface (see Sec. 25.125(a)), but approvals have 
been granted for steep approaches that use a landing screen height of 
35 feet. The final takeoff speed would be defined as the speed of the 
airplane that exists at the end of the takeoff path in the en route 
configuration with one engine inoperative.
    The FAA also proposes to add the abbreviations VSR, VSR0, 
and VSR1 to part 1, and use them in part 25 to denote the 
reference stall speed corresponding to different airplane 
configurations. In addition, the FAA proposes adding the abbreviation 
VSW to part 1 to refer to the stall warning speed.
    The FAA proposes to amend Sec. C36.9(e)(1) by replacing ``1.3 
VS + 10 knots'' with ``VREF + 10 knots'' and by removing the 
words ``or the speed used in establishing the approved landing distance 
under the airworthiness regulations constituting the type certification 
basis of the airplane, whichever speed is greatest.'' The words 
proposed to be deleted would no longer be necessary because VREF 
would denote the speed used in establishing the approved landing 
distance under the airworthiness regulations constituting the type 
certification basis of the airplane. Also, VREF would refer to the 
speed at the landing screen height, regardless of whether that speed 
for a particular airplane is 1.3 VS, 1.23 VSR, or some higher 
speed.
    In the same manner, the FAA proposes to amend Sec. 97.3(b) by 
replacing ``1.3 VS0'' with ``VREF.'' As noted above, 
VREF would refer to the speed at the landing screen height used in 
establishing the approved landing distance under the airworthiness 
regulations constituting the type certification basis of the airplane, 
regardless of whether that speed for a particular airplane is 1.3 
VS, 1.23 VSR, or some higher speed.
    These proposals have been discussed extensively with the European 
Joint Aviation Authorities (JAA) with the intent of harmonizing the 
certification requirements related to stall speed for transport 
category airplanes. The JAA intend to introduce an equivalent proposal 
to amend the Joint Aviation Requirements-25 (JAR-25). JAR-25 prescribes 
the airworthiness standards for transport category airplanes that are 
accepted by the aviation regulatory authorities of 23 European nations. 
When it is published, the JAA proposal will be placed in the docket for 
this rulemaking.

Regulatory Evaluation Summary

Preliminary Regulatory Evaluation, Initial Regulatory Flexibility 
Determination, and Trade Impact Assessment

    Proposed changes to Federal regulations must undergo several 
economic analyses. First, Executive Order 12866 directs that each 
Federal agency shall propose or adopt a regulation only upon a reasoned 
determination that the benefits of the intended regulation justify its 
costs. Second, the Regulatory Flexibility Act of 1980 requires agencies 
to analyze the economic effect of regulatory changes on small entities. 
Third, the Office of Management and Budget directs agencies to assess 
the effects of regulatory changes on international trade. In conducting 
these analyses, the FAA has determined that this proposed rule: (1) 
Would generate benefits that justify its costs and is not a 
``significant regulatory action'' as defined in the Executive Order; 
(2) is not significant as defined in DOT's Regulatory Policies and 
Procedures; (3) would not have a significant impact on a substantial 
number of small entities; and (4) would not constitute a barrier to 
international trade. These analyses, available in the docket, are 
summarized below.

Regulatory Evaluation Summary

Costs
    The proposed requirements would apply to future type certificated 
transport category airplanes and generally would not impose significant 
additional costs on manufacturers. One major manufacturer demonstrated 
adherence to the 1-g stall speed basis in recent FAA special conditions 


[[Page 1264]]
applicable to several models of advanced technology airplanes. Other 
manufacturers have requested certification to the 1-g stall speed basis 
through equivalent safety findings for airplanes with conventional 
flight control systems.
    Cost estimates provided by manufacturers generally did not vary 
significantly. Data provided by a manufacturer of part 25 small 
airplanes, however, showed costs several hundred thousand dollars 
higher than the norm. That manufacturer estimated that short-term costs 
(mostly non-recurring) to convert to the new stall speed basis would be 
over $1 million and that increased costs on a program-by-program basis 
would ``be substantial.'' Because of the gross nature of these 
estimates and because of the inability to segment them on a per-
certification basis, they have not been incorporated into this 
analysis. The FAA invites manufacturers to provide detailed cost 
estimates during the public comment period.
    Although several sections of part 25 would be revised by the 
proposal, only five merit analysis: Sections 25.103 (Stall speed), 
25.107 (Takeoff speeds), 25.125 (Landing), 25.143 (General) (under 
Controllability and Maneuverability), and 25.207 (Stall warning).
Section 25.103 (Stall Speed)
    The proposal to redefine the reference stall speed as a 1-g stall 
speed could result in a net reduction in certification costs for part 
25 large airplanes. In some recent airplane designs, manufacturers have 
used the 1-g stall speed as the reference stall speed. Calculation of 
the reference stall speed (VSR) is within the range of 
instrumentation currently available and additional instrumentation 
would not be required. Existing techniques to determine minimum speed 
in the stalling maneuver require six to eight independent stalls at 
various flap settings; determination of 1-g stall speed could require 
approximately half as many. Cost-savings could be in the range of 
$50,000 to $100,000 per type certification.
    Recent part 25 small transport category airplane certifications, on 
the other hand, have not been based on the 1-g stall speed. 
Consequently, additional instrumentation and analysis would be 
required. Incremental one-time costs for a part 25 small airplane 
design would be approximately $70,000. However, cost savings 
attributable to reduced testing could be realized in future 
certifications (see previous paragraph re part 25 large airplanes).
Section 25.107 (Takeoff Speeds)
    The proposed changes to this section, by virtue of the new 
maneuvering requirements of Sec. 25.143(g), could affect airplane 
operators if the proposed maneuvering requirements necessitate higher 
takeoff/climb speeds and lower passenger/cargo capacity on length-
limited runways. Because of the myriad combinations of airplanes, 
runways, passenger/cargo loads, etc., the FAA is unable to estimate 
potential capacity limitations. The FAA invites interested parties to 
provide estimates of such effects during the public comment period.
Section 25.125 (Landing)
    As in the case of Sec. 25.107 above, the proposed changes to this 
section could potentially affect operators by virtue of the new 
maneuvering requirements in Sec. 25.143(g). Again, the FAA invites 
interested parties to submit cost estimates during the public comment 
period.
Section 25.143 (General)
    Incremental costs that would be incurred by manufacturers to 
determine minimum maneuvering margins are estimated to total 
approximately $150,000 per part 25 large airplane type certification 
and approximately $50,000 per part 25 small airplane type 
certification.
Section 25.207 (Stall Warning)
    Incremental costs that would be incurred by manufacturers to 
provide sufficient stall warning at the various proposed slow-down 
speeds and configurations are estimated to total approximately $120,000 
per part 25 large airplane type certification and approximately 
$200,000 per part 25 small airplane type certification.
Total Costs
    Manufacturers of part 25 large airplanes have already incurred the 
major portion of the start-up costs to convert to a 1-g stall speed 
system and would therefore experience lower incremental costs than 
manufacturers of part 25 small airplanes. The estimated costs to meet 
the revised standards would total approximately $195,000 per part 25 
large airplane type certification (costs associated with Secs. 25.143 
and 25.207 reduced by the midpoint of the cost-savings range of 
Sec. 25.103). Assuming 500 airplanes produced under one type 
certification, this would equate to $390 per airplane.
    Manufacturers of part 25 small airplanes would experience one-time 
costs of $70,000 in conjunction with Sec. 25.103. In addition, costs 
for each future type certification would total approximately $250,000 
(attributable to Secs. 25.143 and 25.207), or about $500 per airplane 
over a 500 airplane production run. A portion of these costs may be 
offset by reduced testing requirements per revised Sec. 25.103. The 
potential operating costs of proposed Secs. 25.107 and 25.125 have not 
been estimated in this evaluation; the FAA invites interested parties 
to provide cost estimates during the public comment period.
Benefits
    Redefining the airplane reference stall speed as the 1-g stall 
speed would result in a higher level of safety in those cases where 
current methods could result in artificially low operating speeds. New 
requirements for minimum maneuvering margins would assure that safe 
margins are obtained at the minimum operating speeds, thus diminishing 
the possibility of inadvertent stalls at critical flight stages.
    A review of National Transportation Safety Board accident reports 
for the years 1983-1992 does not indicate that any accidents have been 
caused by inconsistent/inappropriate reference stall speeds. There were 
several accidents in which inadvertent stalls were cited as a 
contributing factor, but pilot error (e.g., airspeed not properly 
maintained) was the probable cause rather than inherent problems with 
the reference stall speed. In spite of the absence of directly aligned 
accidents, the FAA postulates that, without the revisions in stall 
speed as proposed or effected through special conditions, safety could 
reach unacceptably low levels. The benefits associated with avoiding a 
single accident would far exceed the costs of the proposed rule.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (RFA) was enacted by 
Congress to insure that small entities are not unnecessarily or 
disproportionately burdened by Government regulations. The RFA requires 
agencies to determine whether proposed rules would have ``a significant 
economic impact on a substantial number of small entities'' and, in 
cases where they would, to conduct a Regulatory Flexibility Analysis. 
As prescribed in implementing FAA Order 2100.14A, the size threshold 
for a small aircraft manufacturer is one having 75 or fewer employees. 
Since there are no manufacturers of part 25 airplanes with 75 or fewer 
employees, the proposed rule would not have a significant economic 
impact on a substantial number of small entities.

[[Page 1265]]


International Trade Impact Assessment

    The proposed rule would not constitute a barrier to international 
trade, including the export of U.S. airplanes to foreign markets and 
the import of foreign airplanes into the U.S. Instead, the proposed 
changes would harmonize with corresponding proposals of the European 
Joint Aviation Authorities, thereby lessening restraints on trade.

Federalism Implications

    The amended regulations proposed in this rulemaking would not have 
substantial direct effects on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government. Therefore, 
in accordance with Executive Order 12612, it is determined that this 
proposal would not have sufficient federalism implications to warrant 
preparing a Federalism Assessment.

Conclusion

    Because the proposed changes to redefine the reference stall speed 
for transport category airplanes as the 1-g stall speed are not 
expected to result in substantial economic cost, the FAA has determined 
that this proposed regulation would not be significant under Executive 
Order 12866. Because this is an issue which has not prompted a great 
deal of public concern, the FAA has determined that this action is not 
significant under DOT Regulatory Policies and Procedures (44 FR 11034, 
February 25, 1979). In addition since there are no small entities 
affected by this proposed rulemaking, the FAA certifies, under the 
criteria of the Regulatory Flexibility Act, that this rule, if adopted, 
will not have a significant economic impact, positive or negative, on a 
substantial number of small entities. An initial regulatory evaluation 
of the proposal, including a Regulatory Flexibility Determination and 
Trade Impact Analysis, has been placed in the docket. A copy may be 
obtained by contacting the person identified under FOR FURTHER 
INFORMATION CONTACT.

List of Subjects

14 CFR Part 1

    Air transportation.

14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

14 CFR Part 36

    Agriculture, Aircraft, Noise control.

14 CFR Part 97

    Air traffic control, Airports, Navigation (air), Weather.

The Proposed Amendments

    Accordingly, the Federal Aviation Administration (FAA) proposes to 
amend 14 CFR parts 1, 25, 36, and 97 of the Federal Aviation 
Regulations (FAR) as follows:

PART 1--DEFINITIONS AND ABBREVIATIONS

    1. The authority citation for part 1 is revised to read as follows:

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

    2. Section 1.1 is amended by adding new definitions in alphabetical 
order to read as follows:


Sec. 1.1  General definitions.

* * * * *
    Final takeoff speed means the speed of the airplane that exists at 
the end of the takeoff path in the en route configuration with one 
engine inoperative.
* * * * *
    Reference landing speed means the speed of the airplane, in a 
specified landing configuration, at the point where it descends through 
the landing screen height in the determination of the land distance for 
manual landings.
* * * * *
    3. Section 1.2 is amended by adding new terms in alphabetical order 
to read as follows:


Sec. 1.2  Abbreviations and symbols.

* * * * *
    VFTO means final takeoff speed.
* * * * *
    VREF means reference landing speed.
* * * * *
    VSR means reference stall speed.
    VSR0 means reference stall speed in the landing configuration.
    VSR1 means reference stall speed in a specific configuration.
    VSW means speed at which onset of natural or artificial stall 
warning occurs.
* * * * *

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

    4. The authority citation for part 25 is revised to read as 
follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 22704.

    5. Section 25.103 is revised to read as follows:


Sec. 25.103  Stall speed.

    (a) The reference stall speed, VSR, is a calibrated airspeed 
as defined in paragraph (c) of this section. VSR is determined 
with--
    (1) Engines idling, or, if that resultant thrust causes an 
appreciable decrease in stall speed, not more than zero thrust at the 
stall speed;
    (2) Propeller pitch controls (if applicable) in the takeoff 
position;
    (3) The airplane in other respects (such as flaps and landing gear) 
in the condition existing in the test in which VSR is being used;
    (4) The weight used when VSR is being used as a factor to 
determine compliance with a required performance standard;
    (5) The center of gravity position that results in the highest 
value of reference stall speed; and
    (6) The airplane trimmed for straight flight at a speed selected by 
the applicant, but not less than 1.13 VSR and not greater than 1.3 
VSR.
    (b) Starting from the stabilized trim condition, apply elevator 
control to decelerate the airplane so that the speed reduction does not 
exceed one knot per second.
    (c) The reference stall speed, VSR, is a calibrated airspeed 
determined in the stalling maneuver. VSR may not be less than a 1-
g stall speed. VSR is expressed as:
[GRAPHIC][TIFF OMITTED]TP18JA96.000

where--

VCLMAX = Speed occurring when lift coefficient is first a maximum. 
In addition, if the stalling maneuver is limited by a device that 
commands an abrupt nose down pitch (e.g., a stick pusher), VCLMAX 
may not be less than the speed existing at the instant the device 
operates; and
nZW = Flight patch normal load factor (not greater than 1.0) at 
VCLMAX.

    6. Section 25.107 is amended by revising paragraphs (b)(1) 
introductory text, (b)(2) introductory text, (c)(1) and (c)(2), and by 
adding new paragraphs (c)(3) and (g) to read as follows:


Sec. 25.107  Takeoff speeds.

* * * * *
    (b) * * *
    (1) 1.13 VSR for--
* * * * *
    (2) 1.08 VSR for--
* * * * *
    (c) * * *
    (1) V2MIN;
    (2) VR plus the speed increment attained (in accordance with 
Sec. 25.111(c)(2)) before reaching a height of 35 feet above the 
takeoff surface; and

[[Page 1266]]

    (3) A speed that provides the maneuvering capability specified in 
Sec. 25.143(g).
* * * * *
    (g) VFTO, in terms of calibrated airspeed, must be selected by 
the applicant to provide at least the gradient of climb required by 
Sec. 25.121(c), but may not be less than--
    (1) 1.18 VSR; and
    (2) A speed that provides the maneuvering capability specified in 
Sec. 25.143(g).
    7. Section 25.111 is amended by revising paragraph (a) introductory 
text to read as follows:


Sec. 25.111  Takeoff path.

    (a) The takeoff path extends from a standing start to a point in 
the takeoff at which the airplane is 1,500 feet above the takeoff 
surface, or at which the transition from the takeoff to the en route 
configuration is completed and VFTO is reached, whichever point is 
higher. In addition--
* * * * *
    8. Section 25.119 is amended by revising the section heading and 
paragraph (b) to read as follows:


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

* * * * *
    (b) A climb speed of not more than VREF.
    9. Section 25.121 is amended by revising paragraphs (c) 
introductory text, (d) introductory text, (d)(2) and (d)(3), and by 
adding paragraph (d)(4) to read as follows:


Sec. 25.121  Climb: One-engine-inoperative.

* * * * *
    (c) Final takeoff. In the en route configuration at the end of the 
takeoff path determined in accordance with Sec. 25.111, 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 and with--
* * * * *
    (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, 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--
    (1) * * *
    (2) The maximum landing weight;
    (3) A climb speed established in connection with normal landing 
procedures, but not more than 1.4 VSR; and
    (4) Landing gear retracted.
    10. Section 25.125 is amended by revising paragraph (a)(2) to read 
as follows:


Sec. 25.125  Landing.

    (a) * * *
    (2) A stabilized approach, with a calibrated airspeed of VREF, 
must be maintained down to the 50 foot height. VREF may not be 
less than--
    (i) 1.23 VSR0,
    (ii) VMCL established under Sec. 25.149(f); and
    (ii) A speed that provides the maneuvering capability specified in 
Sec. 25.143(g).
* * * * *
    11. Section 25.143 is amended by adding a new paragraph (g) to read 
as follows:


Sec. 25.143  General.

* * * * *
    (g) The maneuvering capabilities in a constant speed coordinated 
turn at forward center of gravity, as specified in the following table, 
must be free of stall warning or other characteristics that might 
interfere with normal maneuvering:

----------------------------------------------------------------------------------------------------------------
                                                                       Maneuvering                              
                                                                        bank angle                              
              Configuration                           Speed                in a         Thrust/power setting    
                                                                       coordinated                              
                                                                           turn                                 
----------------------------------------------------------------------------------------------------------------
Takeoff..................................  V2........................    30 deg.    Asymmetric WAT-limited.1    
Takeoff..................................  V2+XX 2...................    40 deg.    All-engines-operating       
                                                                                     climb.3                    
En route.................................  VFTO......................    40 deg.    Asymmetric WAT-limited.1    
Landing..................................  VREF......................    40 deg.    Symmetric for -3 deg. flight
                                                                                     path angle.                
----------------------------------------------------------------------------------------------------------------
\1\ A combination of weight, altitude, and temperature (WAT) such that the thrust or power setting produces the 
  minimum climb gradient specified in Sec.  25.121 for the flight condition.                                    
\2\ Airspeed approved for all-engines-operating initial climb.                                                  
\3\ That thrust or power setting which, in the event of failure of the critical engine and without any crew     
  action to adjust the thrust or power of the remaining engines, would result in the thrust or power specified  
  for the takeoff condition at V2, or any lesser thrust or power setting that is used for all engines-operating 
  initial climb procedures.                                                                                     

    12. Section 25.145 is amended by revising paragraphs (a) 
introductory text, (a)(1), (b)(1), (b)(4), (b)(6), and (c) introductory 
text to read as follows:


Sec. 25.145  Longitudinal control.

    (a) It must be possible, at any point between the trim speed 
prescribed in Sec. 25.103(a)(6) and the stall, to pitch the nose 
downward so that the acceleration to this selected trim speed is prompt 
with--
    (1) The airplane trimmed at the trim speed prescribed in 
Sec. 25.103(a)(6);
 * * * * *
    (b) * * *
    (1) With power off, flaps retracted, and the airplane trimmed at 
1.3 VSR1, extend the flaps as rapidly as possible while 
maintaining the airspeed at approximately 30 percent above the 
reference stall speed existing at each instant throughout the maneuver.
 * * * * *
    (4) With power off, flaps retracted, and the airplane trimmed at 
1.3 VSR1, rapidly set go-around power or thrust while maintaining 
the same airspeed.
 * * * * *
    (6) With power off, flaps extended, and the airplane trimmed at 1.3 
VSR1, obtain and maintain airspeeds between VSW and either 
1.6 VSR1 or VFE, whichever is lower.
    (c) It must be possible, without exceptional piloting skill, to 
prevent loss of altitude when complete retraction of the high lift 
devices from any position is begun during steady, straight, level 
flight at 1.08 VSR1 for propeller powered airplanes, or 1.13 
VSR1 for turbojet powered airplanes, with--
 * * * * *


Sec. 25.147  [Amended]

    13. Section 25.147 is amended in paragraphs (a) introductory text, 
(a)(2), (c) introductory text, and (d) by revising the expression ``1.4 
VS1'' to read ``1.3 VSR1''.


Sec. 25.149  [Amended]

    14. Section 25.149 is amended in paragraph (c) introductory text by 
revising the expression ``1.2 VS'' to read ``1.13 VSR.''


Sec. 25.161  [Amended]

    15. Section 25.161 is amended in paragraphs (b), (c)(1), (c)(2), 
(c)(3) and (d) introductory text by revising the expression ``1.4 
VS1'' to read ``1.3 VSR1''; and in paragraph (e)(3) by 
revising the expression ``0.013 VS02'' to read 
``0.013VSR02''.


Sec. 25.175  [Amended]

    16. Section 25.175 is amended in paragraphs (a)(2), (b)(1) 
introductory text, (b)(2) introductory text, (b)(3) 

[[Page 1267]]
introductory text and (c)(4) by revising the expression ``1.4 
VS1'' to read ``1.3 VSR1'', in paragraph (b)(2)(ii) by 
revising the expression ``VMO+1.4 VS1/2'' to read 
``(VMO+1.3 VSR1)/2'', in paragraph (c) introductory text by 
revising the expressions ``1.1 VS1'' to read ``VSW'' and 
``1.8 VS1'' to read ``1.7 VSR1'', in paragraph (d) 
introductory text by revising the expressions ``1.1 VS0'' to read 
``VSW'' and ``1.3 VS0'' to read ``1.7 VSR0'', and in 
paragraph (d)(5) by revising the expression ``1.4 VSO'' to read 
``1.3 VSR0''.


Sec. 25.177  [Amended]

    17. Section 25.177 is amended in paragraph (c) by revising the 
expression ``1.2 VS1'' to read ``1.13 VSR1''.


Sec. 25.181  [Amended]

    18. Section 25.181 is amended in paragraphs (a) introductory text 
and (b) by revising the reference ``1.2 VS'' to read ``1.13 
VSR''.
    19. Section 25.201 is amended by revising paragraphs (a)(2) and 
(b)(4) to read as follows:


Sec. 25.201  Stall demonstration.

    (a) * * *
    (2) The power necessary to maintain level flight at 1.5 VSR1 
(where VSR1 corresponds to the reference stall speed with flaps in 
the approach position, the landing gear retracted, and the maximum 
landing weight).
    (b) * * *
    (4) The airplane trimmed for straight flight at the speed 
prescribed in Sec. 25.103(a)(6).
* * * * *
    20. Section 25.207 is amended by revising paragraphs (b) and (c), 
and by adding new paragraphs (d), (e), and (f) 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.
    (c) When the speed is reduced at rates not exceeding one knot per 
second, with engines idling and throttles closed, stall warning must 
begin, in each normal configuration, at a speed, VSW, exceeding 
the reference stall speed by not less than three knots or three 
percent, whichever is greater. For the purposes of this paragraph, the 
reference stall speed is as defined in Sec. 25.103, except that 
Sec. 25.103(a)(5) does not apply. Stall warning must continue 
throughout the demonstration, until the angle of attack is reduced to 
approximately that at which stall warning is initiated.
    (d) In addition to the requirements of paragraph (c) of this 
section, when devices that abruptly push the nose down at a selected 
angle of attack (e.g., stick pushers) are installed, the stall warning 
must occur at a speed not less than five knots or five percent, 
whichever is greater, above the speed at which the device activates.
    (e) In slow-down turns up to 1.5g at entry rates up to 3 knots per 
second, with the flaps and landing gear in any normal position, the 
stall warning margin must be sufficient to allow the pilot to prevent 
stalling when recovery is initiated not less than one second after the 
onset of stall warning.
    (f) Stall warning must also be provided in each abnormal 
configuration of the high lift devices that is likely to be used in 
flight following system failures (including all configurations covered 
by Airplane Flight Manual procedures).


Sec. 25.231  [Amended]

    21. Section 25.231 is amended in paragraph (a)(2) by revising the 
word ``altitude'' to read ``attitude'' and by revising the expression 
``80 percent of VS1'' to read ``75 percent of VSR1''.


Sec. 25.233  [Amended]

    22. Section 25.233 is amended in paragraph (a) by revising the 
reference ``0.2 VS0'' to read ``0.2 VSR0''.


Sec. 25.237  [Amended]

    23. Section 25.237 is amended in paragraphs (a), (b)(1), and (b)(2) 
by revising the reference ``0.2 VS0'' to read ``0.2 VSR0''.
    24. Action 25.735 is amended by revising paragraphs (f)(2) and (g) 
to read as follows:


Sec. 25.735  Brakes.

* * * * *
    (f) * * *
    (2) Instead of a rational analysis, the kinetic energy absorption 
requirements for each main wheel brake assembly may be derived from the 
following formula, which must be modified in the case of unequal 
braking distribution, which assumes an equal distribution of braking 
between main wheels:

    KE=0.0443 (WV2/N)
where--

KE=Kinetic energy per wheel (ft.-lb.);
W=Design landing weight (lb.);
V=VREF/1.3
VREF=Airplane steady landing approach speed, in knots, at the 
maximum design landing weight and in the landing configuration at sea 
level; and
N=Number of main wheels with brakes.

    (g) The minimum speed rating of each main wheel-brake assembly 
(that is, the initial speed used in the dynamometer tests) may not be 
more than the V used in the determination of kinetic energy in 
accordance with paragraph (f) of this section, assuming that the test 
procedures for wheel-brake assemblies involve a specified rate of 
deceleration, and, therefore, for the same amount of kinetic energy, 
the rate of energy absorption (the power absorbing ability of the 
brake) varies inversely with the initial speed.


Sec. 25.773  [Amended]

    25. Section 25.773 is amended in paragraph (b)(1)(i) by revising 
the expression ``1.6 VS1'' to read ``1.5 VSR1''.


Sec. 25.1001  [Amended]

    26. Section 25.1001 is amended in paragraphs (c)(1) and (c)(3) by 
revising the expression ``1.4 VS1'' to read ``1.3 VSR1''.


Sec. 25.1323  [Amended]

    27. Section 25.1323 is amended in paragraph (c)(1) by revising the 
expression ``1.3 VS1'' to read ``1.23 VSR1'' and in paragraph 
(c)(2) by revising the expression ``1.3 VS0'' to read ``1.23 
VSR0''.


Sec. 25.1325  [Amended]

    28. Section 25.1325 is amended in paragraph (e) by revising the 
expressions ``1.3 VS0'' and ``1.8 VS1'' to read ``1.23 
VSR0'' and ``1.7 VSR1'', respectively.


Sec. 25.1587  [Amended]

    29. Section 25.1587 is amended in paragraph (b)(2) by revising the 
expression ``VS'' to read ``VSR''.

PART 36--NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS 
CERTIFICATION

    30. The authority citation for part 36 continues to read as 
follows:

    Authority: 42 U.S.C. 4321 et seq., 49 U.S.C. 106(g), 40113, 
44701-44702, 44704, 44715; sec. 305, Pub. L. 96-193, 94 Stat. 50, 
57; E.O. 11514, 35 FR 4247, 3 CFR, 1966-1970 comp., p. 902.

    31. Appendix C to part 36, Section C36.9 is amended by revising 
paragraph (e)(1) to read as follows:

[[Page 1268]]


Appendix C to Part 36--Noise Levels for Transport Category and Turbojet 
Powered Airplanes Under Sec. 36.201

* * * * *

Sec. C36.9 Approach Reference and Test Limitations

* * * * *
    (e) * * *
    (1) For subsonic airplanes a steady approach speed of VREF + 
10 knots must be established and maintained over the approach measuring 
point.
* * * * *

PART 97--STANDARD INSTRUMENT APPROACH PROCEDURES

    32. The authority citation for part 97 is revised to read as 
follows:

    Authority: 49 U.S.C. 106(g), 40103, 40106, 40113, 40114, 40120, 
44502, 44514, 44701, 44719, 44721-44722.

    33. Section 97.3 is amended by revising the first two sentences of 
paragraph (b) introductory text to read as follows:


Sec. 97.3  Symbols and terms used in procedures.

* * * * *
    (b) Aircraft approach category means a grouping of aircraft based 
on a speed of VREF at the maximum certificated landing weight. 
VREF and the maximum certificated landing weight are those values 
as established for the aircraft by the certification authority of the 
country of registry. * * *
* * * * *
    Issued in Washington, DC on November 29, 1995.
Thomas E. McSweeny,
Director, Aircraft Certification Service.
[FR Doc. 96-415 Filed 1-17-96; 8:45 am]
BILLING CODE 4910-13-M