Airworthiness Directives; McDonnell Douglas Model MD-11 Series Airplanes

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 93-NM-231-AD; Amendment 39-8806; AD 94-02-08]

Airworthiness Directives; McDonnell Douglas Model MD-11 Series

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that

is applicable to certain McDonnell Douglas Model MD-11 series

airplanes. This action requires an inspection to detect chafing damage

to certain wiring in the main avionics rack, repair or replacement of

damaged wiring, and modification of the wiring installation. This

amendment is prompted by a report of a chafed wire harness found on the

main avionics rack on one airplane that resulted in arcing damage to

the wire harness and adjacent structure. The actions specified in this

AD are intended to prevent chafing of the main avionics rack wiring,

which could result in arcing and a fire in the wire bundle; this could

lead to damage to aircraft systems and loss of associated aircraft

functions.

DATES: Effective February 10, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of February 10, 1994.

Comments for inclusion in the Rules Docket must be received on or

before March 28, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 93-NM-231-AD, 1601 Lind Avenue SW., Renton,

Washington 98055-4056.

The service information referenced in this AD may be obtained from

McDonnell Douglas Corporation, P.O. Box 1771, Long Beach, California

90846-0001, Attention: Business Unit Manager, Technical Publications,

C1-HDR (54-60). This information may be examined at the FAA, Transport

Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington; or at

the Los Angeles Aircraft Certification Office, FAA, Transport Airplane

Directorate, 3229 East Spring Street, Long Beach, California; or at the

Office of the Federal Register, 800 North Capitol Street NW., suite

700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Brett Portwood, Aerospace Engineer,

Systems & Equipment Branch, ANM-132L, Los Angeles Aircraft

Certification Office, FAA, Transport Airplane Directorate, 3229 East

Spring Street, Long Beach, California 90806-2425; telephone (310) 988-

5347; fax (310) 988-5210.

SUPPLEMENTARY INFORMATION: Recently, one operator of McDonnell Douglas

Model MD-11 series airplanes reported one instance of the auto ground

spoiler failing to arm on one airplane. Investigation revealed two

wires that had burnt in half and several charred wires on shelf 3 of

the aft section of the main avionics rack. These wires apparently had

chafed and shorted on the screws that attach the wire bundle trough

assembly to the rack. Additionally, the protective tape was worn from

the attach screw heads. The operator then conducted a fleet inspection

and found additional wire chafing at the same location on another

airplane. The operator also found worn protective tape (exposed screw

heads) at various locations on the avionics racks on other airplanes.

Chafing of the wiring in the main avionics rack, if not detected and

corrected in a timely manner, could result in arcing and a fire in the

wire bundle; this could lead to damage to aircraft systems and the loss

of associated aircraft functions.

The FAA has reviewed and approved McDonnell Douglas MD-11 Alert

Service Bulletin A24-75, dated December 22, 1993, that describes

procedures for performing a visual inspection to detect chafing damage

to the wire harness located on the aft side of the main avionics rack

on shelves 1 through 4. It also describes procedures for repairing or

replacing damaged wiring, and modifying the wiring installation by

bonding nylon sheets between the wire harnesses and the protective tape

on the screw heads.

Since an unsafe condition has been identified that is likely to

exist or develop on other Model MD-11 series airplanes of the same type

design, this AD is being issued to prevent chafing of the main avionics

rack wiring, which could result in arcing and fire in the wire bundle,

and lead to damage to aircraft systems and the subsequent loss of

associated aircraft functions. This AD requires a detailed visual

inspection to detect chafing damage to the wire harnesses located on

the aft side of the main avionics rack on shelves 1 through 4. Any

damaged wiring must be replaced or repaired prior to further flight.

Additionally, operators are required to modify the wiring installation

by bonding nylon sheets between the wire harnesses and the protective

tape on the screw heads. The actions are required to be accomplished in

accordance with the service bulletin described previously.

This is considered interim action until final action is identified,

at which time the FAA may consider additional rulemaking.

Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for prior

public comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting flight safety and, thus, was not preceded by

notice and an opportunity for public comment, comments are invited on

this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All

communications received on or before the closing date for comments will

be considered, and this rule may be amended in light of the comments

received. Factual information that supports the commenter's ideas and

suggestions is extremely helpful in evaluating the effectiveness of the

AD action and determining whether additional rulemaking action would be

needed.

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the 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 that

summarizes each FAA-public contact concerned with the substance of this

AD 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 93-NM-231-AD.'' The postcard will be date stamped and

returned to the commenter.

The regulations adopted herein will 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 final

rule does not have sufficient federalism implications to warrant the

preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency

regulation that must be issued immediately to correct an unsafe

condition in aircraft, and is not a ``significant regulatory action''

under Executive Order 12866. It has been determined further that this

action involves an emergency regulation under DOT Regulatory Policies

and Procedures (44 FR 11034, February 26, 1979). If it is determined

that this emergency regulation otherwise would be significant under DOT

Regulatory Policies and Procedures, a final regulatory evaluation will

be prepared and placed in the Rules Docket. A copy of it, if filed, may

be obtained from the Rules Docket at the location provided under the

caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by

reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends 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:

94-02-08 McDonnell Douglas: Amendment 39-8806. Docket 93-NM-231-AD.

Applicability: Model MD-11 series airplanes; manufacturer's

fuselage numbers 447 through 558, inclusive; certificated in any

category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent chafing of the main avionics rack wiring, which could

result in arcing and a fire in the wire bundle, damage to aircraft

systems, and subsequent loss of associated aircraft functions,

accomplish the following:

(a) Within 30 days after the effective date of this AD, conduct

a one-time detailed visual inspection to detect chafing damage to

the wire harnesses located on the aft side of the main avionics rack

on shelves 1 through 4, left and right sides, in accordance with

McDonnell Douglas MD-11 Alert Service Bulletin A24-75, dated

December 22, 1993.

(b) If no damage is detected during the inspection required by

paragraph (a) of this AD, prior to further flight, modify the wiring

installation in accordance with the service bulletin.

(c) If any damage is detected during the inspection required by

paragraph (a) of this AD, prior to further flight, accomplish the

requirements of paragraphs (c)(1), (c)(2), and (c)(3) of this AD in

accordance with the service bulletin:

(1) Repair or replace the damaged wiring;

(2) Modify the wiring installation; and

(3) Perform a return-to-service test of the affected wiring

system.

(d) 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). 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.

(e) Special flight permits may be issued in accordance with FAR

21.197 and 21.199 to operate the airplane to a location where the

requirements of this AD can be accomplished.

(f) The inspection, repair, replacement, and modification shall

be done in accordance with McDonnell Douglas MD-11 Alert Service

Bulletin A24-75, dated December 22, 1993. This incorporation by

reference was approved by the Director of the Federal Register in

accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be

obtained from McDonnell Douglas Alert Service Bulletin A24-75, dated

December 22, 1993. Copies may be inspected at the FAA, Transport

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

at the Los Angeles Aircraft Certification Office, FAA, Transport

Airplane Directorate, 3229 East Spring Street, Long Beach,

California; or at the Office of the Federal Register, 800 North

Capitol Street NW., suite 700, Washington, DC.

(g) This amendment becomes effective on February 10, 1994.

Issued in Renton, Washington, on January 14, 1994.

John J. Hickey,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-1464 Filed 1-25-94; 8:45 am]

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