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

[[Page 31648]]

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]

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