AD 99-19-07

[Federal Register Volume 64, Number 224 (Monday, November 22, 1999)]
[Rules and Regulations]
[Pages 63576-63584]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-30133]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-141-AD; Amendment 39-11296; AD 99-19-07]
RIN 2120-AA64


Airworthiness Directives; Gulfstream American (Frakes Aviation) 
Model G-73 (Mallard) and G-73T 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 certain Gulfstream American (Frakes Aviation) Model G-73 
(Mallard) and G-73T series airplanes, that requires revising the 
Airplane Flight Manual (AFM) to include requirements for activation of 
the airframe pneumatic deicing boots. This amendment is prompted by 
reports of inflight incidents and an accident that occurred in icing 
conditions where the airframe pneumatic deicing boots were not 
activated. The actions specified by this AD are intended to ensure that 
flightcrews activate the pneumatic wing and tail deicing boots at the 
first signs of ice accumulation. This action will prevent reduced 
controllability of the aircraft due to adverse aerodynamic effects of 
ice adhering to the airplane prior to the first deicing cycle.

EFFECTIVE DATE: December 27, 1999.

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; or at the FAA, Rotorcraft Directorate, 1601 Meacham 
Boulevard, Fort Worth, Texas.

FOR FURTHER INFORMATION CONTACT: Efran Esparza, Aerospace Engineer, 
Airplane Certification Office, ASW-150, FAA, Rotorcraft Directorate, 
1601 Meacham Boulevard, Fort Worth, Texas 76137-4298; telephone (817) 
222-5130; fax (817) 222-5960.

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 certain Gulfstream American 
(Frakes Aviation) Model G-73 (Mallard) and G-73T series airplanes was 
published in the Federal Register on July 16, 1999 (64 FR 38355). That 
action proposed to require revising the Airplane Flight Manual (AFM) to 
include requirements for activation of the airframe pneumatic deicing 
boots.

Related Proposals

    In addition to the proposed rule described previously, in June 
1999, the FAA issued 18 other similar proposals that address the 
subject unsafe condition on various airplane models (see below for a 
listing of all 19 proposed rules). Those 18 proposals also were 
published in the Federal Register on July 16, 1999. (Docket 99-NM-153-
AD, for Fokker Model F-27 Mark 100, 200, 300, 400, 500, 600, and 700 
series airplanes, was also issued as a supplemental notice of proposed 
rulemaking, and published in the Federal Register on August 6, 1999.) 
This final rule contains the FAA's responses to all relevant public 
comments received for each of these proposed rules.

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      Manufacturer airplane model                           Number                     Federal Register citation
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Cessna Aircraft Company Models 500,      99-NM-136-AD                                 64 FR 38374
 550, and 560 Series Airplanes.

[[Page 63577]]

 
Sabreliner Corporation Models 40, 60,    99-NM-137-AD                                 64 FR 38358
 70, and 80 Series Airplanes.
Gulfstream Aerospace Model G-159 Series  99-NM-138-AD                                 64 FR 38341
 Airplanes.
McDonnell Douglas Models DC-3 and DC-4   99-NM-139-AD                                 64 FR 38325
 Series Airplanes.
Mitsubishi Heavy Industries Model YS-11  99-NM-140-AD                                 64 FR 38371
 and YS-11A Series Airplanes.
Gulfstream American (Frakes Aviation)    99-NM-141-AD                                 64 FR 38355
 Model G-73 (Mallard) and G-73T Series
 Airplanes.
Lockheed, Models L-14 and L-18 Series    99-NM-142-AD                                 64 FR 38338
 Airplanes.
Fairchild Models F-27 and FH-227 Series  99-NM-143-AD                                 64 FR 38322
 Airplanes.
Aerospatiale Models ATR-42/ATR-72        99-NM-144-AD                                 64 FR 38368
 Series.
Jetstream Model BAe ATP Airplanes......  99-NM-145-AD                                 64 FR 38351
Jetstream Model 4101 Airplanes.........  99-NM-146-AD                                 64 FR 38335
British Aerospace Model HS 748 Series    99-NM-147-AD                                 64 FR 38319
 Airplanes.
Saab Model SF340A/SAAB 340B/SAAB 2000    99-NM-148-AD                                 64 FR 38365
 Series Airplanes.
CASA Model C-212/CN-235 Series           99-NM-149-AD                                 64 FR 38348
 Airplanes.
Dornier Model 328-100 Series Airplanes.  99-NM-150-AD                                 64 FR 38332
Lockheed Model 1329-23 and 1329-25       99-NM-151-AD                                 64 FR 38316
 (Lockheed Jetstar) Series Airplanes.
de Havilland Model DHC-7/DHC-8 Series    99-NM-152-AD                                 64 FR 38362
 Airplanes.
Fokker Model F-27 Mark 100/200/300/400/  99-NM-153-AD                                 64 FR 42870
 500/600/700/050 Series Airplanes.
Short Brothers Model SD3-30/SD3-60/SD3-  99-NM-154-AD                                 64 FR 38329
 SHERPA Airplanes.
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Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the following comments received.

1. Support for the Rule

    One commenter supports the proposed rule.

2. Request To Withdraw the Proposal: No Unsafe Condition

    Several commenters request that the proposal be withdrawn because 
no unsafe condition exists on certain airplanes. One of these 
commenters states that the FAA is merely speculating that the proposed 
Airplane Flight Manual (AFM) revision will improve safety. Further, the 
commenter contends that the FAA cannot substantiate that the proposed 
AFM revision will prevent ice bridging. This same commenter also asks 
if the FAA met its own standards by testing the proposed procedure on 
each of the affected airplanes.
    The FAA does not concur that no unsafe condition exists. As 
discussed in the preamble of the proposed rule, the FAA has reviewed 
the icing-related incident history of certain airplanes, and has 
determined that icing incidents may have occurred because pneumatic 
deicing boots were not activated at the first evidence of ice 
accretion. As a result, the handling qualities or the controllability 
of the airplane may have been reduced due to the accumulated ice. The 
FAA also discussed an accident that occurred as a result of the failure 
of the flightcrew to activate the wing and tail pneumatic deicing 
boots.
    Although there may have been no reported cases of incidents or 
accidents on a specific airplane model, the potential still exists for 
reduced controllability of all airplanes equipped with pneumatic 
deicing boots due to adverse aerodynamic effects of ice adhering to the 
airplane. This AD addresses this unsafe condition.
    Further, ice bridging of deicing boots was considered during 
development of the proposed rule. A broad representation of the 
aviation community was consulted, including airframe manufacturers, air 
carriers, airline pilot associations, airplane owner associations, 
deicing boot manufacturers, and National Aeronautics and Space 
Administration (NASA). Also, articles readily accessible by the general 
piloting community solicited operational information concerning ice 
bridging of deicing boots. The FAA considers that the general consensus 
of the aviation community is that little or no evidence exists of ice 
bridging of deicing boots with current deicing boot designs, and ice 
that is not shed after the initial boot cycle continues to increase in 
thickness and sheds during subsequent cycles.
    In addition, many airplanes equipped with pneumatic deicing boots 
to protect the engine are operated when icing conditions are present, 
i.e., visible moisture and a specific temperature are observed. As 
discussed in Comment #3 (following this response), at least two 
airplane manufacturers have issued AFM's that contain procedures to 
activate the deicing boots at the first sign of ice accumulation. The 
FAA is unaware of any ice bridging problems associated with early 
operations of either the airfoil or engine pneumatic deicing boots.
    In response to the commenter's question regarding the FAA meeting 
its own standards, the FAA infers that the commenter is requesting the 
basis for the FAA's determination that the proposed procedures are 
safe. Most aircraft certification programs have not considered the 
reduced controllability of the aircraft due to adverse aerodynamic 
effects of ice adhering to the pneumatic boots. The requirements of 
this AD (activation of the deicing boot system at the first sign of ice 
formation anywhere on the aircraft, or upon annunciation from an ice 
detector system, whichever occurs first, along with the periodic 
cycling of the boots) will minimize the ice accretions and thereby 
reduce the adverse aerodynamic effects.

3. Request To Withdraw the Proposal: Possible Adverse Effects of 
Residual Ice

    Several commenters state that deicing boots do the best job of 
shedding ice on a single cycle, if ice is permitted to accrete to \1/4\ 
or \1/2\ inch before activation of the boots. One of these commenters 
further contends that the effect of continuous cycling in auto mode may 
not produce a clean shed of ice on each activation, and that residual 
ice must be taken into consideration before any revision to the AFM is 
required. Another commenter states that, although operation in the 
continuous mode upon first indication of ice accretion would eliminate 
the problem of identification of accretion, the commenter is concerned 
that there would then be a potential for degraded performance due to 
residual ice.
    The FAA does not concur that the proposal should be withdrawn 
because of concerns over residual ice. Operation of pneumatic deicing 
boots typically results in persistent ice accretions on the boot 
surfaces, even when  Except if the AFM otherwise specifies that deicing 
boots should not be used for certain phases of flight (e.g., take-
off, final approach, and landing), compliance with the following is 
required.
     Wing and Tail Leading Edge Pneumatic Deicing Boot 
System, if installed, must be activated:


[[Page 63584]]


--At the first sign of ice formation anywhere on the aircraft, or 
upon annunciation from an ice detector system, whichever occurs 
first; and
--The system must either be continued to be operated in the 
automatic cycling mode, if available; or the system must be manually 
cycled as needed to minimize the ice accretions on the airframe.

     The wing and tail leading edge pneumatic deicing boot 
system may be deactivated only after completion of an entire deicing 
cycle after leaving icing conditions.
    (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, Airplane Certification Office, ASW-
150, FAA, Rotorcraft Directorate. The request shall be forwarded 
through an appropriate FAA Operations Inspector, who may add 
comments and then send it to the Manager, Airplane Certification 
Office, ASW-150 ACO.

    Note 1: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Airplane Certification Office, ASW-150 ACO.

    (c) Special flight permits may be issued in accordance with 
Secs. 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 December 27, 1999.

    Issued in Renton, Washington, on November 10, 1999.
John J. Hickey,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-30133 Filed 11-19-99; 8:45 am]
BILLING CODE 4910-13-U