Airworthiness Directives; McDonnell Douglas Model DC-9-80 Series Airplanes and Model MD-88 Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-87-AD]

Airworthiness Directives; McDonnell Douglas Model DC-9-80 Series

Airplanes and Model MD-88 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 DC-9-80 series

airplanes and Model MD-88 airplanes. This proposal would require

modification of the engine nose cowl. This proposal is prompted by

several in-flight incidents in which the engine nose cowl separated or

nearly separated from the airplane. The actions specified by the

proposed AD are intended to prevent separation of the engine nose cowl

from the airplane during severe vibration of the engine.

DATES: Comments must be received by September 12, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-87-AD, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056. Comments may be inspected at this location

between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal

holidays.

The service information referenced in the proposed rule may be

obtained from McDonnell Douglas Corporation, P.O. Box 1771, Long Beach,

California 90801-1771, Attention: Business Unit Manager, Technical

Administrative Support, Dept. L51, M.C. 2-98. This information may be

examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue,

SW., Renton, Washington; or at the FAA, Transport Airplane Directorate,

Los Angeles Aircraft Certification Office, 3229 East Spring Street,

Long Beach, California.

FOR FURTHER INFORMATION CONTACT: Robert Baitoo, Aerospace Engineer,

Propulsion Branch, ANM-141L, FAA, Transport Airplane Directorate, Los

Angeles Aircraft Certification Office, 3229 East Spring Street, Long

Beach, California 90806-2425; telephone (310) 988-5245; fax (310) 988-

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 94-NM-87-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-87-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The FAA has received reports of several in-flight incidents that

have occurred on McDonnell Douglas Model DC-9-80 series airplanes in

which the engine nose cowl separated or nearly separated from these

airplanes. Investigation revealed that these separations occurred

following severe vibration of the engine due to failures of the first

stage fan blade. The cause of these separations has been attributed to

loose or missing attachment bolts of the engine nose cowl. This

condition, if not corrected, could result in separation of the engine

nose cowl from the airplane during severe vibration of the engine.

The FAA has reviewed and approved McDonnell Douglas MD-80 Alert

Service Bulletin A71-61, dated May 18, 1994, which describes procedures

for modification of the left and right engine nose cowls. This

modification entails removal of attachment bolts and nutplates,

replacement of nutplates with self-locking nuts and washers on the

engine ``A'' flange, and reversal of attachment bolt direction

(bolthead facing forward). This modification will ensure the integrity

of the nose cowl attachment assembly so as to minimize the possibility

of separation of the engine nose cowl from the airplane during severe

vibration of the engine.

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 modification of the left and right engine

nose cowls. The actions would be required to be accomplished in

accordance with the alert service bulletin described previously.

There are approximately 1,062 McDonnell Douglas Model DC-9-80

series airplanes and Model MD-88 airplanes of the affected design in

the worldwide fleet. The FAA estimates that 540 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. Required

parts would cost approximately $100 per airplane. Based on these

figures, the total cost impact of the proposed AD on U.S. operators is

estimated to be $232,200, or $430 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:

McDonnell Douglas: Docket 94-NM-87-AD.

Applicability: Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83

(MD-83), and DC-9-87 (MD-87) series airplanes and Model MD-88

airplanes; as listed in McDonnell Douglas MD-80 Alert Service

Bulletin A71-61, dated May 18, 1994; certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent the engine nose cowl separating from the airplane

during severe engine vibration, accomplish the following:

(a) Within 8 months after the effective date of this AD, modify

the left and right engine nose cowls in accordance with McDonnell

Douglas MD-80 Alert Service Bulletin A71-61, dated May 18, 1994.

Note 1: Modification in accordance with either Figure 1, Figure

2, or Figure 3 of the alert service bulletin is acceptable for

compliance with this paragraph.

(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 2: 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 July 21, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-18284 Filed 7-26-94; 8:45 am]

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