[Federal Register Volume 61, Number 2 (Wednesday, January 3, 1996)]
[Proposed Rules]
[Pages 134-136]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-44]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-177-AD]


Airworthiness Directives; McDonnell Douglas Model DC-10-10, -15, 
-30, -40, and KC-10A (Military) Series Airplanes

AGENCY: Federal Aviation Administration, DOT.


[[Page 135]]

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-10-10, -15, -30, -40, and KC-10A (military) series airplanes. This 
proposal would require modification of the AC generator control units. 
This proposal is prompted by reports of loss of electrical power from 
two generators and an engine that flamed out due to an overfrequency 
condition of a generator. The actions specified by the proposed AD are 
intended to prevent an overfrequency condition of a generator, which 
could lead to the loss of all electrical power of the airplane.

DATES: Comments must be received by February 28, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-177-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, 3855 Lakewood Boulevard, 
Long Beach, California 90846, Attention: Technical Publications 
Business Administration, Department C1-L51 (2-60). 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: Natalie Phan-Tran, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft 
Certification Office, 3960 Paramount Boulevard, Lakewood, California 
90712; telephone (310) 627-5343; fax (310) 627-5210.

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 95-NM-177-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. 95-NM-177-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports of loss of electrical power from two 
generators and an engine that flamed out on Model DC-10 series 
airplanes, which resulted in multiple malfunctions of the electrical 
system. Investigation revealed that the cause of the loss of electrical 
power was attributed to an overfrequency condition in one of the three 
generators, which resulted from certain failure modes of the constant 
speed drive (CSD). Since all three generators are in parallel, the 
overfrequency condition of one generator increased the speed of the 
other two generators, which led to failure of the generator fans. If 
the generator fans fail, all electrical power from the generators could 
be lost; this situation could lead to loss of all electrical power of 
the airplane.
    The FAA has reviewed and approved McDonnell Douglas Service 
Bulletin DC10-24-111 RO1, Revision 1, dated August 14, 1995, which 
describes procedures for modification of the AC generator control units 
(GCU). This modification adds a circuit that will provide overfrequency 
protection. The circuit will isolate an overspeeding generator before 
there is a perceptible power interruption on the other buses.
    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 modification of the AC GCU's. The actions 
would be required to be accomplished in accordance with the service 
bulletin described previously.
    There are approximately 419 Model DC-10-10, -15, -30, -40, and KC-
10A (military) series airplanes of the affected design in the worldwide 
fleet. The FAA estimates that 276 airplanes of U.S. registry would be 
affected by this proposed AD, that it would take approximately 5 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 $2,896 per generator control unit; there are 4 units per 
airplane. Based on these figures, the cost impact of the proposed AD on 
U.S. operators is estimated to be $3,279,984, or $11,884 per airplane.
    The 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. 
    
[[Page 136]]


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 USC 106(g), 40101, 40113, 44701.


Sec. 39.13  [Amended] -

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

McDonnell Douglas: Docket 95-NM-177-AD. -
    Applicability: Model DC-10-10, -15, -30, -40, and KC-10A 
(military) series airplanes, as listed in McDonnell Douglas Service 
Bulletin DC10-24-111 RO1, Revision 1, dated August 14, 1995; 
certificated in any category.

     -Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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) of this AD 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 prevent an overfrequency condition of the generator, which 
could result in loss of all electrical power of the airplane, 
accomplish the following: -
    (a) Within 2 years after the effective date of this AD, modify 
the AC generator control units (GCU) in accordance with McDonnell 
Douglas Service Bulletin DC10-24-111 RO1, Revision 1, dated August 
14, 1995. -
    (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 27, 1995.

Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-44 Filed 1-2-96; 8:45 am]
BILLING CODE 4910-13-U