Airworthiness Directives; McDonnell Douglas Model DC-9-10, -20, - 30, -40, and -50 Series Airplanes, and Model C-9 (Military) Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-144-AD]

Airworthiness Directives; McDonnell Douglas Model DC-9-10, -20, -

30, -40, and -50 Series Airplanes, and Model C-9 (Military) Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes the adoption of a new airworthiness

directive (AD) that is applicable to certain McDonnell Douglas Model

DC-9-10, -20, -30, -40, and -50 series airplanes, and Model C-9

(military) airplanes. This proposal would require replacement of the

engine nose cowl attaching bolts and the installation of bearing plates

on the nose cowl attach ring. This proposal is prompted by incidents in

which the nose cowl separated from the airplane due to the elongation

and/or breakout of the nose cowl's attachment ring holes, and failure

of the attaching bolts. The actions specified by the proposed AD are

intended to prevent separation of the engine nose cowl from the

airplane, which could result in damage to the airplane structure or

could present a hazard to persons or property on the ground.

DATES: Comments must be received by December 13, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-144-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, Los Angeles Aircraft

Certification Office, Transport Airplane Directorate, 3229 East Spring

Street, Long Beach, California.

FOR FURTHER INFORMATION CONTACT: Robert Baitoo, Aerospace Engineer,

Propulsion Branch ANM-140L, FAA, Los Angeles Aircraft Certification

Office, Transport Airplane Directorate, 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-144-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-144-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion -

The FAA has received reports of five incidents, involving McDonnell

Douglas Model DC-9 series airplanes, in which the engine nose cowl

separated from the airplane. Investigation revealed that these

incidents of separation of the nose cowls have occurred following

severe engine vibration that was caused by failures of the first stage

or second stage fan blades. The cause of the separations has been

attributed to elongation and/or breakout of the engine nose cowl's

attachment ring holes. Additionally, in some cases, the attach bolts

had failed. This condition, if not corrected, could lead to separation

of the engine nose cowl from the airplane, which could result in damage

to the airplane fuselage or other structure, or could present a hazard

to persons or property on the ground. -

The FAA has reviewed and approved McDonnell Douglas DC-9 Alert

Service Bulletin A71-63, dated July 21, 1994, which describes

procedures for replacement of the left and right engine nose cowl

attaching bolts with new bolts of increased strength. It also describes

procedures for adding bearing plates on the nose cowl attach ring.

These actions will minimize the possibility of the engine nose cowl

separating from the airplane. -

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 replacement of the nose cowl attaching bolts

and the installation of bearing plates on the nose cowl attach ring.

The actions would be required to be accomplished in accordance with the

service bulletin described previously.-

There are approximately 892 Model DC-9-10, -20, -30, -40, and -50

series airplanes, and Model C-9 (military) airplanes of the affected

design in the worldwide fleet. The FAA estimates that 557 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 $1,200 per airplane. Based on these

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

estimated to be $852,210, or $1,530 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-144-AD.

-Applicability: Model DC-9-10, -20, -30, -40, and -50 series

airplanes, and Model C-9 (military) airplanes; as listed in

McDonnell Douglas DC-9 Alert Service Bulletin A71-63, dated July 21,

1994; certificated in any category. -

Compliance: Required as indicated, unless accomplished

previously. -

To prevent separation of the engine nose cowl from the airplane,

accomplish the following: -

(a) Within 12 months after the effective date of this AD,

replace the left and right engine nose cowl attaching bolts and

install bearing plates, in accordance with McDonnell Douglas DC-9

Alert Service Bulletin A71-63, dated July 21, 1994. -

(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 October 12, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-25694 Filed 10-17-94; 8:45 am]

BILLING CODE 4910-13-U