Airworthiness Directives; Aerospatiale Model ATR72-100 and -200 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-36-AD]

Airworthiness Directives; Aerospatiale Model ATR72-100 and -200

Series Airplanes

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 certain Model ATR72-100 and -200

series airplanes. This proposal would require a one-time dye penetrant

inspection to detect cracking in certain hinge pins of the nose landing

gear (NLG), and replacement of cracked pins with crack-free pins. This

proposal is prompted by reports of cracking of certain hinge pins in

the NLG. The actions specified by the proposed AD are intended to

prevent collapse of the NLG due to cracking of the hinge pins.

DATES: Comments must be received by July 15, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 94-NM-36-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.

The service information referenced in the proposed rule may be

obtained from Aerospatiale, 316 Route de Bayonne, 31060 Toulouse, Cedex

03, France. This information may be examined at the FAA, Transport

Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT: Sam Grober, Aerospace Engineer,

Standardization Branch, ANM-113, FAA, Transport Airplane Directorate,

1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206)

227-1187; fax (206) 227-1320.

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 94-NM-36-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. 94-NM-36-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The Direction General de l'Aviation Civile (DGAC), which is the

airworthiness authority for France, recently notified the FAA that an

unsafe condition may exist on certain Aerospatiale Model ATR72-100 and

-200 series airplanes. The DGAC advises that cracking has been found on

the hinge pins during routine overhaul of the nose landing gear (NLG)

on Model ATR72-100 and -200 series airplanes. The cause for this

cracking has been attributed to improper heat treatment during

manufacture of the hinge pins. The defective pins have been isolated to

those manufactured by Nardi having part number D56867 and serial

numbers beginning with the letter ``N.'' This condition, if not

corrected, could result in collapse of the NLG due to cracking of the

hinge pins.

Avions de Transport Regional has issued Service Bulletin ATR72-32-

1021, dated January 17, 1994, that describes procedures for a one-time

dye penetrant inspection to detect cracking in certain hinge pins of

the NLG, and replacement of cracked pins with crack-free pins. The DGAC

classified this service bulletin as mandatory and issued French

Airworthiness Directive 94-002-019(B), dated January 5, 1994, in order

to assure the continued airworthiness of these airplanes in France.

This airplane model is manufactured in France and is type

certificated for operation in the United States under the provisions of

Sec. 21.29 of the Federal Aviation Regulations and the applicable

bilateral airworthiness agreement. Pursuant to this bilateral

airworthiness agreement, the DGAC has kept the FAA informed of the

situation described above. The FAA has examined the findings of the

DGAC, reviewed all available information, and determined that AD action

is necessary for products of this type design that are certificated for

operation in the United States.

Since an unsafe condition has been identified that is likely to

exist or develop on other airplanes of the same type design registered

in the United States, the proposed AD would require a one-time dye

penetrant inspection to detect cracking in certain hinge pins in the

NLG, and replacement of cracked pins with crack-free pins. The actions

would be required to be accomplished in accordance with the service

bulletin described previously.

The FAA estimates that 28 airplanes of U.S. registry would be

affected by this proposed AD, that it would take approximately 6 work

hours per airplane to accomplish the proposed actions, and that the

average labor rate is $55 per work hour. Based on these figures, the

total cost impact of the proposed AD on U.S. operators is estimated to

be $9,240, or $330 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 14

CFR part 39 of the Federal Aviation Regulations 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:

Aerospatiale: Docket 94-NM-36-AD.

Applicability: Model ATR72-100 and -200 series airplanes

equipped with hinge pins installed at the nose landing gear (NLG)

that are manufactured by Nardi, have part number D56867, and have

serial numbers beginning with the letter ``N''; certificated in any

category.

Compliance: Required as indicated, unless accomplished

previously.

-To prevent collapse of the NLG due to cracking of the hinge

pins, accomplish the following:

-(a) Prior to the accumulation of 10,000 total landings or

within 1,000 landings after the effective date of this AD, whichever

occurs later, perform a dye penetrant inspection to detect cracking

in the hinge pins of the NLG in accordance with Avions de Transport

Regional Service Bulletin ATR72-32-1021, dated January 17, 1994.

-(1) If no cracking is found, prior to further flight, reinstall

that hinge pin in accordance with the service bulletin.

-(2) If cracking is found, prior to further flight, install a

new hinge pin or a pin that has been previously inspected and found

to be crack-free, in accordance with the service bulletin.

-(b) As of the effective date of this AD, no hinge pin

manufactured by Nardi having part number D56867 and any serial

number beginning with the letter ``N,'' shall be installed on the

NLG of any airplane, unless that pin has been previously inspected

and has been found to be crack-free, in accordance Avions de

Transport Regional Service Bulletin ATR72-32-1021, dated January 17,

1994.

-(c) 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, Standardization Branch, ANM-113,

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,

Standardization Branch, ANM-113.

Note: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Standardization Branch, ANM-113.

(d) Special flight permits may be issued in accordance with

Federal Aviation Regulations (FAR) 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 May 12, 1994. Original signed

by:

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-12124 Filed 5-17-94; 8:45 am]

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