Airworthiness Directives; McDonnell Douglas Model MD-11 Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-67-AD; Amendment 39-8805; AD 94-02-07]

Airworthiness Directives; McDonnell Douglas Model MD-11 Series

Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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

applicable to certain McDonnell Douglas Model MD-11 series airplanes,

that requires replacing the anti-skid control unit. This amendment is

prompted by three reports of failure of the center landing gear drag

link, after which the center landing gear swung aft and struck the

fuselage. The actions specified by this AD are intended to prevent

failure of the center landing gear drag link, which could result in

extensive damage to the fuselage structure.

DATES: Effective February 28, 1994. The incorporation by reference of

certain publications listed in the regulations is approved by the

Director of the Federal Register as of February 28, 1994.

ADDRESSES: The service information referenced in this AD may be

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

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

Publications--Technical Administrative Support, C1-L5B. This

information may be examined at the Federal Aviation Administration

(FAA), Transport Airplane Directorate, Rules Docket, 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; or at the Office of the Federal Register, 800

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

FOR FURTHER INFORMATION CONTACT: Andrew Gfrerer, Aerospace Engineer,

Systems and Equipment Branch, ANM-131L, FAA, Transport Airplane

Directorate, Los Angeles Aircraft Certification Office, 3229 East

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

5338; fax (310) 988-5210.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations to include an airworthiness directive (AD) that is

applicable to certain McDonnell Douglas Model MD-11 series airplanes

was published in the Federal Register on July 16, 1993 (58 FR 38321).

That action proposed to require replacing the anti-skid control unit.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

One commenter supports the proposal.

One commenter suggests that the proposed AD action is inappropriate

for two reasons:

1. Drag link failures occur only with the use of autobraking.

Therefore, if only manual brakes are used, there should be no

requirement to modify the anti-skid control unit.

2. Failure of the center landing gear drag link does not pose

sufficient risk to the airframe to warrant AD action.

The FAA does not concur with the commenter's suggestion that this

AD action is not warranted. As for the commenter's Item 1, the FAA

points out that there has been at least one case of failure of the

center gear with the application of manual brakes prior to touchdown of

the nose gear wheel. By replacing the Part Number (P/N) 6005304-1

control unit with the P/N 6005304-2 unit (as required by this AD),

center gear braking is inhibited both manually and through the use of

autobrakes until nose gear touchdown.

As for the commenter's Item 2, the FAA notes that there have been

at least three in-service failures of center landing gear drag links

that have caused significant structural damage to the airplane. In each

occurrence, the failed drag link allowed the center landing gear to

swing aft and strike the fuselage. Additionally, there are numerous

other possible scenarios involving similar failures that could result

in damage to the hydraulic and electrical systems of the airplane. The

center landing gear is also needed to properly distribute the

airplane's weight for heavy weight landings. For these reasons, the FAA

considers that failure of the center landing gear drag link does

present an unsafe condition sufficient to warrant mandated corrective

action. The appropriate vehicle for mandating such corrective action is

the airworthiness directive.

Two commenters request that the proposed compliance time of 9

months be extended to 12 months. The manufacturer has indicated that

the fleet of affected Model MD-11's could not be retrofitted within 9

months, given the current schedule of modifying the subject part on a

rotatable basis and the capacity of the manufacturer to modify the

control units. The FAA concurs with the commenter's request. Extending

the compliance time an additional 3 months will not adversely affect

safety and will allow the affected fleet to be modified in an orderly

manner, thereby minimizing the costs associated with special airplane

scheduling. Paragraph (a) of the final rule has been revised to specify

a compliance time of 12 months.

One commenter requests that the wording of references to the anti-

skid control unit be clarified. The preamble to the notice referred to

``the anti-skid control unit for the center landing gear;'' however,

this control unit controls all of the landing gears, not just the

center landing gear. The FAA agrees that clarification of this point is

needed and, where appropriate, has changed the wording in this final

rule accordingly.

After careful review of the available data, including the comments

noted above, the FAA has determined that air safety and the public

interest require the adoption of the rule with the changes previously

described. The FAA has determined that these changes will neither

increase the economic burden on any operator nor increase the scope of

the AD.

There are approximately 86 McDonnell Douglas Model MD-11 series

airplanes of the affected design in the worldwide fleet. The FAA

estimates that 32 airplanes of U.S. registry will be affected by this

AD, that it will take approximately 1 work hour per airplane to

accomplish the required actions, and that the average labor rate is $55

per work hour. Required parts will be provided by the manufacturer at

no cost to the operator. Based on these figures, the total cost impact

of the AD on U.S. operators is estimated to be $1,760, or $55 per

airplane. This total cost figure assumes that no operator has yet

accomplished the requirements of this AD.

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.

For the reasons discussed above, I certify that this action (1) Is

not a ``significant regulatory action'' under Executive Order 12866;

(2) is not a ``significant rule'' under DOT Regulatory Policies and

Procedures (44 FR 11034, February 26, 1979); and (3) 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 final evaluation has been prepared for this action

and it is contained in the Rules Docket. A copy of it 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:

94-02-07 McDonnell Douglas: Amendment 39-8805. Docket 93-NM-67-AD.

Applicability: Model MD-11 series airplanes, as listed in

McDonnell Douglas MD-11 Service Bulletin 32-30, dated March 3, 1993;

certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent potential failure of the center gear drag link, which

could lead to extensive damage to the fuselage structure, accomplish

the following:

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

replace the anti-skid control unit, part number 6005304-1, with a

new anti-skid control unit, part number 6005304-2, in accordance

with McDonnell Douglas MD-11 Service Bulletin 32-30, dated March 3,

1993.

(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 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 FAR

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

requirements of this AD can be accomplished.

(d) The replacement shall be done in accordance with McDonnell

Douglas MD-11 Service Bulletin 32-30, dated March 3, 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 Corporation, P.O.

Box 1771, Long Beach, California 90801-1771, Attention: Business

Unit Manager, Technical Publications--Technical Administrative

Support, C1-L5B. Copies may be inspected 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; or at the Office of the Federal Register, 800 North

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

(e) This amendment becomes effective on February 28, 1994.

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

John J. Hickey,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-1465 Filed 1-27-94; 8:45 am]

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