[Federal Register Volume 61, Number 89 (Tuesday, May 7, 1996)]
[Rules and Regulations]
[Pages 20671-20672]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-10776]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-15-AD; Amendment 39-9596; AD 96-09-20]
RIN 2120-AA64


Airworthiness Directives; British Aerospace Model HS 748 Series 
Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to all British Aerospace Model HS 748 series airplanes, that 
requires revising the Airplane Flight Manual (AFM) to provide the 
flight crew with recognition cues for, and procedures for exiting from, 
severe icing conditions, and to limit or prohibit the use of various 
flight control devices. This amendment is prompted by results of a 
review of the requirements for certification of the airplane in icing 
conditions, new information on the icing environment, and icing data 
provided currently to the flight crews. The actions specified by this 
AD are intended to minimize the potential hazards associated with 
operating the airplane in severe icing conditions by providing more 
clearly defined procedures and limitations associated with such 
conditions.

EFFECTIVE DATE: June 11, 1996.

ADDRESSES: Information pertaining to this rulemaking action may be 
examined at the Federal Aviation Administration (FAA), Transport 
Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: William Schroeder, Aerospace Engineer, 
Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 
227-2148; fax (206) 227-1149.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to all British Aerospace Model HS 748 
series airplanes was published in the Federal Register on January 25, 
1996 (61 FR 2139). That action proposed to require revising the 
Airplane Flight Manual (AFM) to specify procedures that would prohibit 
flight in freezing rain or freezing drizzle conditions (as determined 
by certain visual cues), limit or prohibit the use of various flight 
control devices, and provide the flight crew with recognition cues for, 
and procedures for exiting from, severe icing conditions.

Disposition of Comments

    For the disposition of comments on this rulemaking action, see 
Docket No. 95-NM-146-AD; Amendment 39-9604; AD 96-09-28, Airworthiness 
Directives; Aerospatiale Model ATR-42 and ATR-72 Series Airplanes, 
published elsewhere in this issue of the Federal Register.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    Currently, there are no Model HS 748 series airplanes on the U.S. 
Register. However, should an affected airplane be imported and placed 
on the U.S. Register in the future, it would require approximately 1 
work hour to accomplish the required actions, at an average labor rate 
of $60 per work hour. Based on these figures, the cost impact of this 
AD would be $60 per airplane.
    In addition, the FAA recognizes that this AD may impose operational 
costs. However, those costs are incalculable because the frequency of 
occurrence of the specified conditions and the associated additional 
flight time are indeterminable. Nevertheless, because of the severity 
of the unsafe condition addressed, the FAA has determined that 
continued operational safety necessitates the imposition of these 
costs.

Regulatory Impact

    The regulations adopted herein will 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 final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a 
significant economic impact, positive or negative, on a substantial 
number of small entities under the criteria of the Regulatory 
Flexibility Act. A final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

[[Page 20672]]

PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 USC 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

96-09-20  Jetstream Aircraft Limited (Formerly British Aerospace, 
Aircraft Group): Amendment 39-9596. Docket 96-NM-15-AD.

    Applicability: All Model HS 748 series airplanes, certificated 
in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (b) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To minimize the potential hazards associated with operating the 
airplane in severe icing conditions by providing more clearly 
defined procedures and limitations associated with such conditions, 
accomplish the following:
    (a) Within 30 days after the effective date of this AD, 
accomplish the requirements of paragraphs (a)(1) and (a)(2) of this 
AD.

    Note 2: Operators must initiate action to notify and ensure that 
flight crewmembers are apprised of this change.

    (1) Revise the FAA-approved Airplane Flight Manual (AFM) by 
incorporating the following into the Limitations Section of the AFM. 
This may be accomplished by inserting a copy of this AD in the AFM.

``WARNING

    Severe icing may result from environmental conditions outside of 
those for which the airplane is certificated. Flight in freezing 
rain, freezing drizzle, or mixed icing conditions (supercooled 
liquid water and ice crystals) may result in ice build-up on 
protected surfaces exceeding the capability of the ice protection 
system, or may result in ice forming aft of the protected surfaces. 
This ice may not be shed using the ice protection systems, and may 
seriously degrade the performance and controllability of the 
airplane.
     During flight, severe icing conditions that exceed 
those for which the airplane is certificated shall be determined by 
the following visual cues. If one or more of these visual cues 
exists, immediately request priority handling from Air Traffic 
Control to facilitate a route or an altitude change to exit the 
icing conditions.

--Unusually extensive ice accreted on the airframe in areas not 
normally observed to collect ice
--Accumulation of ice on the upper surface of the wing aft of the 
protected area

     Since the autopilot may mask tactile cues that indicate 
adverse changes in handling characteristics, use of the autopilot is 
prohibited when any of the visual cues specified above exist, or 
when unusual lateral trim requirements or autopilot trim warnings 
are encountered while the airplane is in icing conditions.
     All icing detection lights must be operative prior to 
flight into icing conditions at night. [NOTE: This supersedes any 
relief provided by the Master Minimum Equipment List (MMEL).]''
    (2) Revise the FAA-approved AFM by incorporating the following 
into the Procedures Section of the AFM. This may be accomplished by 
inserting a copy of this AD in the AFM.

``THE FOLLOWING WEATHER CONDITIONS MAY BE CONDUCIVE TO SEVERE IN-FLIGHT 
ICING

     Visible rain at temperatures below 0 degrees Celsius 
ambient air temperature.
     Droplets that splash or splatter on impact at 
temperatures below 0 degrees Celsius ambient air temperature.

PROCEDURES FOR EXITING THE SEVERE ICING ENVIRONMENT

    These procedures are applicable to all flight phases from 
takeoff to landing. Monitor the ambient air temperature. While 
severe icing may form at temperatures as cold as -18 degrees 
Celsius, increased vigilance is warranted at temperatures around 
freezing with visible moisture present. If the visual cues specified 
in the Limitations Section of the AFM for identifying severe icing 
conditions are observed, accomplish the following:
     Immediately request priority handling from Air Traffic 
Control to facilitate a route or an altitude change to exit the 
severe icing conditions in order to avoid extended exposure to 
flight conditions more severe than those for which the airplane has 
been certificated.
     Avoid abrupt and excessive maneuvering that may 
exacerbate control difficulties.
     Do not engage the autopilot.
     If the autopilot is engaged, hold the control wheel 
firmly and disengage the autopilot.
     If an unusual roll response or uncommanded roll control 
movement is observed, reduce the angle-of-attack.
     Do not extend flaps during extended operation in icing 
conditions. Operation with flaps extended can result in a reduced 
wing angle-of-attack, with the possibility of ice forming on the 
upper surface further aft on the wing than normal, possibly aft of 
the protected area.
     If the flaps are extended, do not retract them until 
the airframe is clear of ice.
     Report these weather conditions to Air Traffic 
Control.''
    (b) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Standardization Branch, ANM-113, 
FAA, Transport Airplane Directorate. Operators shall submit their 
requests through an appropriate FAA Principal Operations Inspector, 
who may add comments and then send it to the Manager, 
Standardization Branch, ANM-113.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Standardization Branch, ANM-113.

    -(c) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (d) This amendment becomes effective on June 11, 1996.
    Issued in Renton, Washington, on April 24, 1996.
Ronald T. Wojnar
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-10776 Filed 5-1-96; 3:26 pm]
BILLING CODE 4910-13-P