[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), 

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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