[Federal Register Volume 59, Number 143 (Wednesday, July 27, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-18279]
[[Page Unknown]]
[Federal Register: July 27, 1994]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-NM-78-AD]
Airworthiness Directives; McDonnell Douglas Model DC-9-80 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-9-80 series airplanes and Model MD-88 airplanes. This proposal would
require modification of the power transfer unit (PTU). This proposal is
prompted by reports of fatigue cracks found in the drain port housings
of the PTU's on several airplanes. The actions specified by the
proposed 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: Comments must be received by September 9, 1994.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-78-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, Los Angeles Aircraft
Certification Office, Transport Airplane Directorate, 3229 East Spring
Street, Long Beach, California.
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:
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-78-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-78-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has received reports of cracked drain port housings found
on the power transfer units (PTU) installed on five McDonnell Douglas
Model DC-9-80 series airplanes. In one incident, failure of the housing
resulted in the loss of both hydraulic systems, which caused the
airplane to depart from the runway during taxi due to the loss of
braking and nose landing gear steering.
Investigation has revealed that the cause of the cracking is
attributed to fatigue. Further analysis of the hardware has indicated
that the center housing and drain port housing can crack before the
design life of the PTU has been reached. This condition, if not
corrected, could lead to the failure of the housings associated with
the PTU, which in turn could result in the loss of both hydraulic
systems (until the PTU is shut off).
The FAA has reviewed and approved McDonnell Douglas Service
Bulletin 29-53, Revision 1, dated April 21, 1994, that describes
procedures for modification of the center housing and drain port
housing of the PTU. This modification entails replacing the currently
installed cast aluminum housings with wrought aluminum housings, and
reidentifying the part number of the PTU. Such modification will ensure
that the housings meet the PTU design life requirements.
(Note: This service bulletin references Allied Signal Service
Bulletin 4100310-29-0031, Revision 3, dated April 8, 1994, for
detailed modification instructions.)
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 center housing and drain
port housing of the PTU. The actions would be required to be
accomplished in accordance with the McDonnell Douglas service bulletin
described previously.
This proposed AD would not be applicable to airplanes that are
equipped with Vickers PV3-160 engine driven pumps. The FAA finds that
this type of pump provides a pressurized flow of 21 gallons per minute
and, in the event of a PTU crack or failure, that rate of flow would be
adequate to continue pressurizing the affected hydraulic system.
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 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 $55 per work hour. Required parts would cost approximately
$2,912 per airplane. Based on these figures, the total cost impact of
the proposed AD on U.S. operators is estimated to be $1,746,716, or
$3,022 per airplane.
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-78-AD.
Applicability: Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83
(MD-83), DC-9-84 (MD-84), 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 the 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
Sec. Sec. 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 July 20, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 94-18279 Filed 7-26-94; 8:45 am]
BILLING CODE 4910-13-U
