AD 95-14766

[Federal Register Volume 60, Number 116 (Friday, June 16, 1995)] [Proposed Rules] [Pages 31647-31649] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 95-14766]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-NM-19-AD]

Airworthiness Directives; General Dynamics (Convair) Model 240 Series Airplanes, Including Model T-29 (Military) Airplanes; Model 340 and 440 Series Airplanes; and Model C-131 (Military) Airplanes; Including Those Modified for Turbo-Propeller Power

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to various General Dynamics (Convair) airplanes. This proposal would require revising the Airplane Flight Manual to require that the flight crew limit the flap settings during certain icing conditions and air temperatures. This proposal is prompted by reports indicating that incidents involving uncommanded pitch excursions have occurred due to ice contaminated tailplane stall (ICTS) that occurred during or following flight in icing conditions. If flap settings are increased for landing when ICTS is present, elevator control could be affected adversely and the airplane could descend uncontrollably. The actions specified by the proposed AD are intended to ensure that the flight crew is advised of the potential hazard related to increasing the flap settings when ICTS is present, and the procedures necessary to address it.

DATES: Comments must be received by August 14, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 95-NM-19-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Andrew Gfrerer, Aerospace Engineer, Systems and Equipment Branch, ANM-130L, FAA, Transport Airplane Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712; telephone (310) 627-5338; fax (310) 627-5210.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 95-NM-19-AD.'' The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 95-NM-19-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports indicating that incidents involving uncommanded pitch excursions have occurred on various turbo-propeller powered airplanes, including General Dynamics (Convair) airplanes. These pitch excursions were caused by ice contaminated tailplane stall (ICTS), which occurred during or following flight in icing conditions. If the flap settings are increased for landing when ICTS is present, elevator control could be affected adversely. This condition, if not corrected, could result in uncontrollable descent of the airplane. Icing conditions can be encountered during the approach for the landing phase of flight. Further, ice can accumulate on the tailplane before it begins to accumulate on the wings. Since ice may form quickly, in the case of the tailplane, such ice formation could reach hazardous proportions during the approach phase without any prior evidence of its presence in the ``clean'' (cruise) configuration. The flight crew can only determine if ice is forming on the airplane by looking out the window at the wings. If the flight crew does not observe any ice on the wings, they could assume that the airplane is free of ice and proceed to select certain flap settings during the approach phase without properly configuring the airplane for icing conditions by turning on the anti-icing system. In addition, the flight crew may increase the flap settings for landing and, consequently, elevator control can be affected adversely. In response to the reports of uncommanded pitch excursions, the FAA and the National Aeronautics and Space Administration (NASA) sponsored two International Tailplane Icing workshops in November 1991 and April 1993. In addition to representatives from the FAA and NASA, workshop participants included representatives from certain foreign airworthiness authorities, foreign and domestic manufacturers, and industry. As a result of these workshops, emphasis was placed on improving flight crew awareness of ICTS. For the longer term, a review of certain Federal Aviation Regulations (FAR) that pertain to ice protection/detection and tailplane aerodynamic issues also was conducted. Additionally, the FAA conducted flight tests on various turbo- propeller powered airplanes, including General Dynamics (Convair) Model 5800 series airplanes. (This airplane model is similar to a Model 340 series airplane equipped with turbo-prop engines.) During the certification of Model 5800 series airplanes, the FAA performed a series of flight test maneuvers to determine if the airplane would be susceptible to ICTS. Results of these flight test maneuvers indicate that these airplanes are susceptible to ICTS. Such susceptibility is directly related to the angle-of-attack (AOA) of the tailplane and the sensitivity of the airfoil to degradation by contamination often associated with efficient airfoil design. The FAA has issued a number of airworthiness directives (AD) to correct the same unsafe condition described previously on various transport category airplane types. Examples of those AD's include the following:

--AD 86-20-02, amendment 39-5429 (51 FR 34452, September 29, 1986), applicable to Aerospatiale Model ATR-42 series airplanes; --AD 91-16-01, amendment 39-7091 (56 FR 37468, August 7, 1991),

[[Page 31649]] applicable to Mitsubishi Heavy Industries (MHI) Model YS-11 and -11A series airplanes; and --AD 86-06-03 R1, amendment 39-5917 (53 FR 16385, May 9, 1988), applicable to SAAB-Fairchild Model SF-340A series airplanes.

The FAA finds that the FAA-approved Airplane Flight Manual (AFM) for General Dynamics (Convair) Model 240 series airplanes [including Model T-29 (military) airplanes], Model 340 and 440 series airplanes, and Model C-131 (military) airplanes, including those modified for turbo-propeller power, must be revised. This revision must include procedures to ensure that the flight crew does not select a flap setting of more than 30 degrees after icing conditions have been encountered, when icing conditions are anticipated during approach and landing, or when the outside air temperature is +5 degrees Celsius or below and any visible moisture is present. The FAA has determined that such procedures currently are not defined adequately in the AFM for these airplanes. Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require revising the Limitations Section of the FAA- approved AFM to limit flap selection during certain icing conditions and air temperatures. There are approximately 282 Model 240 series airplanes, including Model T-29 (military) airplanes; Model 340 and 440 series airplanes; Model C-131 (military) airplanes, and those models modified for turbo- propeller power; of the affected design in the worldwide fleet. The FAA estimates that 197 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 1 work hour per airplane to accomplish the proposed actions, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $11,820, or $60 per airplane. The total cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The regulations proposed herein 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 the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this proposed regulation (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting 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.

The Proposed Amendment

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

PART 39--AIRWORTHINESS DIRECTIVES

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

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

Sec. 39.13 [Amended]

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

General Dynamics (Convair): Docket 95-NM-19-AD.

Applicability: All Model 240 series airplanes, including Model T-29 (military) airplanes; Model 340 and 440 series airplanes; and Model C-131 (military) airplanes; including those models modified for turbo-propeller power (commonly referred to as Model 580, 600, and 640 series airplanes); certificated in any category. Compliance: Required as indicated, unless accomplished previously. To ensure that the flight crew is advised of the potential hazard associated with increasing the flap settings when ice contaminated tailplane stall (ICTS) is present, and the procedures necessary to address it, accomplish the following: (a) Within 30 days after the effective date of this AD, revise the Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to include the following procedures, which will limit the flap settings during certain icing conditions and air temperatures. This may be accomplished by inserting a copy of this AD in the AFM.

``Flap Limitation in Icing Conditions

Flap selection is limited to a maximum of 30 degrees after icing conditions have been encountered; or when icing conditions are anticipated during approach and landing; or when the outside air temperature is +5 degrees Celsius or below and any visible moisture is present.'' (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, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Los Angeles ACO.

Note: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO.

(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.

Issued in Renton, Washington, on June 12, 1995. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 95-14766 Filed 6-15-95; 8:45 am] BILLING CODE 4910-13-U