Airworthiness Directives; Gulfstream American (Frakes Aviation) Model G-73 (Mallard) and G-73T Series Airplanes

[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.

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

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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. ----------------------------------------------------------------------------------------------------------------

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:

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--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