Airworthiness Directives; McDonnell Douglas Model DC-9, DC-9-80, and C-9 (Military) Series Airplanes, and Model MD-88 Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-194-AD]

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

and C-9 (Military) 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 McDonnell Douglas Model

DC-9, DC-9-80, and C-9 (Military) series airplanes, and Model MD-88

airplanes. This proposal would require repetitive replacement of the

emergency power switch in the overhead switch panel with a new switch.

This proposal is prompted by a report of heavy smoke in the cockpit

coming from the overhead switch panel on a Model DC-9-81 series

airplane. The actions specified by the proposed AD are intended to

ensure replacement of the emergency power switch when it has reached

its maximum life limit; an emergency power switch that is not replaced

could fail and lead to a short in the electrical circuit, which could

result in a fire in the overhead switch panel and smoke in the cockpit.

DATES: Comments must be received by January 31, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 94-NM-194-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, 3960 Paramount Boulevard,

Lakewood, California 90712.

FOR FURTHER INFORMATION CONTACT: Elvin Wheeler, Aerospace Engineer,

Systems and Equipment Branch, ANM-132L, FAA, Transport Airplane

Directorate, Los Angeles Aircraft Certification Office, 3960 Paramount

Boulevard, Lakewood, California 90712; telephone (310) 988-5344; 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-194-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-194-AD, 1601 Lind Avenue, SW., Renton, Washington

98055-4056.

Discussion

The FAA has received a report of heavy smoke in the cockpit coming

from the overhead switch panel on a McDonnell Douglas Model DC-9-81

(MD-81) series airplane. Investigation revealed that the fire had

originated in the area of the emergency power switch in the overhead

switch panel. Further investigation, conducted by Mason Electric

Company (the manufacturer of the emergency power switch), revealed that

the emergency power switch, upon exceeding 10,000 switch cycles (off-

to-on-to-off) can fail due to wear or overstress. If not replaced in a

timely manner, the emergency power switch could fail and lead to a

short in the electrical circuit, which could result in a fire in the

overhead switch panel and smoke in the cockpit.

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

Bulletin 24-150, dated March 28, 1994, which describes procedures for

repetitively replacing the emergency power switch in the overhead

switch panel with a new switch at regular intervals.

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 repetitively replacing the emergency power

switch in the overhead switch panel with a new switch at regular

intervals. The actions would be required to be accomplished in

accordance with the service bulletin described previously.

As a result of recent communications with the Air Transport

Association (ATA) of America, the FAA has learned that, in general,

some operators may misunderstand the legal effect of AD's on airplanes

that are identified in the applicability provision of the AD, but that

have been altered or repaired in the area addressed by the AD. The FAA

points out that all airplanes identified in the applicability provision

of an AD are legally subject to the AD. If an airplane has been altered

or repaired in the affected area in such a way as to affect compliance

with the AD, the owner or operator is required to obtain FAA approval

for an alternative method of compliance with the AD, in accordance with

the paragraph of each AD that provides for such approvals. A note has

been included in this notice to clarify this requirement.

There are approximately 1,990 Model DC-9, DC-9-80, and C-9

(Military) series airplanes and Model MD-88 airplanes of the affected

design in the worldwide fleet. The FAA estimates that 992 airplanes of

U.S. registry would be affected by this proposed AD, that it would take

approximately 2 work hours per airplane to accomplish the proposed

actions, and that the average labor rate is $60 per work hour. Required

parts would cost approximately $1,434 per airplane. Based on these

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

estimated to be $1,541,568, or $1,554 per airplane, per replacement

cycle.

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-194-AD.

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

airplanes; Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83),

and DC-9-87 (MD-87) series airplanes; Model MD-88 airplanes; and C-9

(Military) series airplanes; as listed in McDonnell Douglas DC-9

Service Bulletin 24-150, dated March 28, 1994; certificated in any

category.

Note 1: This AD applies to each airplane identified in the

preceding applicability provision, regardless of whether it has been

modified, altered, or repaired in the area subject to the

requirements of this AD. For airplanes that have been modified,

altered, or repaired so that the performance of the requirements of

this AD is affected, the owner/operator must use the authority

provided in paragraph (b) to request approval from the FAA. This

approval may address either no action, if the current configuration

eliminates the unsafe condition; or different actions necessary to

address the unsafe condition described in this AD. Such a request

should include an assessment of the effect of the changed

configuration on the unsafe condition addressed by this AD. In no

case does the presence of any modification, alteration, or repair

remove any airplane from the applicability of this AD.

Compliance: Required as indicated, unless accomplished

previously.

To ensure replacement of the emergency power switch that have

reached the maximum life limit, accomplish the following:

(a) Prior to the accumulation of 3 years time-in-service on the

emergency power switch in the overhead switch panel, or within 12

months after the effective date of this AD, whichever occurs later,

replace the emergency power switch with a new switch, in accordance

with McDonnell Douglas DC-9 Service Bulletin 24-150, dated March 28,

1994. Thereafter, replace the emergency power switch at intervals

not to exceed the accumulation of 3 years time-in-service on the

switch.

(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 December 14, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-31183 Filed 12-19-94; 8:45 am]

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