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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-78-AD; Amendment 39-9052; AD 94-22-03]

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

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

and Model MD-88 airplanes, that requires modification of the power

transfer unit (PTU). This amendment is prompted by reports of fatigue

cracks found in the drain port housings of the PTU's on several

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

failure of the PTU housing due to fatigue cracking, which could result

in the loss of both hydraulic systems (until the PTU is shut off).

DATES: Effective October 28, 1994.

The incorporation by reference of certain publications listed in

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

of November 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

Administrative Support, Dept. L51, M.C. 2-98. 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, Los Angeles Aircraft Certification Office,

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: Walter Eierman, Systems and Equipment

Branch, ANM-131L, FAA, Transport Airplane Directorate, Los Angeles ACO,

3229 East Spring Street, Long Beach, California 90806-2425; telephone

(310) 988-5336; fax (310) 988-5210.

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

Aviation Regulations (14 CFR part 39) to include an airworthiness

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

DC-9-80 series airplanes and Model MD-88 airplanes was published in the

Federal Register on July 27, 1994 (59 FR 38146). That action proposed

to require modification of the power transfer unit (PTU).

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.

Two commenters requested that the proposed compliance time of

``14,300 flight cycles on the PTU or 9 months after the effective date

of the AD, whichever occurs later,'' be extended. These commenters are

concerned that they will be unable to modify their affected fleets

within the proposed compliance time due to a possible problem in the

availability of an ample number of required parts from the

manufacturer. The FAA does not concur with the commenter's request to

extend the compliance time. In developing an appropriate compliance

time for this action, the FAA considered not only the degree of urgency

associated with addressing the subject unsafe condition, but the

availability of required parts and the practical aspect of installing

the required modification within a maximum interval of time allowable

for all affected airplanes to continue to operate without compromising

safety. The FAA has been advised that an ample number of required parts

will be available for modification of the U.S. fleet within the

proposed compliance period. However, under the provisions of paragraph

(b) of the final rule, the FAA will consider requests for adjustments

to the compliance time if data are submitted to substantiate that such

an adjustment would provide an acceptable level of safety.

The applicability of the final rule has been revised to delete the

reference to Model ``DC-9-84 (MD-84).'' This inclusion of this

reference was in error; no such model of airplane exists.

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 change previously

described. The FAA has determined that this change will neither

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

the AD.

There are approximately 1,074 Model DC-9-80 series airplanes and

Model MD-88 airplanes of the affected design in the worldwide fleet.

The FAA estimates that 578 airplanes of U.S. registry will be affected

by this AD, that it will take approximately 2 work hours per airplane

to accomplish the required actions, and that the average labor rate is

$60 per work hour. Required parts will cost approximately $2,912 per

airplane. Based on these figures, the total cost impact of the AD on

U.S. operators is estimated to be $1,752,496, or $3,032 per airplane.

The total cost impact figure discussed above is based on

assumptions that no operator has yet accomplished any of the

requirements of this AD action, and that no operator would accomplish

those actions in the future if this AD were not adopted.

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 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:

94-22-03 McDonnell Douglas: Amendment 39-9052. Docket 94-NM-78-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 Service Bulletin 29-53,

Revision 1, dated April 21, 1994; excluding airplanes equipped with

Vickers PV3-160 Engine Driven Pumps; certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent loss of both hydraulic systems due to the failure of

the housings of the power transfer unit (PTU), accomplish the

following:

(a) Prior to or upon accumulation of 14,300 flight cycles on the

PTU, or within 9 months after the effective date of this AD,

whichever occurs later, modify the PTU assembly, part number

4100310, in accordance with McDonnell Douglas Service Bulletin 29-

53, Revision 1, dated April 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.

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

Douglas Service Bulletin 29-53, Revision 1, dated April 21, 1994.

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 Administrative Support, Dept. L51, M.C. 2-

98. Copies may be inspected 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; or at

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

suite 700, Washington, DC.

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

Issued in Renton, Washington, on October 19, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-26366 Filed 10-27-94; 8:45 am]

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