[Federal Register Volume 63, Number 2 (Monday, January 5, 1998)]
[Proposed Rules]
[Pages 169-171]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-118]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-78-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 777 Series Airplanes
Equipped With Pratt & Whitney Engines and Used in Extended Range Twin-
Engine Operations (ETOPS)
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 Boeing Model 777 series
airplanes equipped with Pratt & Whitney engines. This proposal would
require replacement of the integrated drive generator (IDG) and the
backup generator with a new IDG and a new backup generator. This
proposal is prompted by reports of IDG shaft failure resulting from
design problems in the hydraulic and mechanical systems of the
generator, and by reports of backup generator failure resulting from
the failure of the oil pressure switch. The actions specified by the
proposed AD are intended to prevent continued degradation of the power
system, which could result in loss of electrical power.
DATES: Comments must be received by February 19, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 97-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 Boeing Commercial Airplane Group, P.O. Box 3707, Seattle,
Washington 98124-2207. This information may be examined at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington.
FOR FURTHER INFORMATION CONTACT: Chris Hartonas, Aerospace Engineer,
Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane
Directorate, Seattle Aircraft Certification Office; 1601 Lind Avenue,
SW., Renton, Washington 98055-4056; telephone (425) 227-2864; fax (425)
227-1181.
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 No. 97-NM-78-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRM's
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules
Docket No. 97-NM-78-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has been monitoring the reliability of the electrical power
system
[[Page 170]]
of the Boeing Model 777 series airplane since its introduction into
service. Design modifications that have improved the reliability of the
electrical power system have been incorporated on Model 777 series
airplanes equipped with Rolls-Royce and General Electric engines; these
modifications are proposed to be incorporated on Model 777 series
airplanes equipped with Pratt & Whitney engines and used in extended
range twin-engine operations (ETOPS) to bring systems reliability
within acceptable levels.
The FAA has received reports indicating that the backup generator
and the shaft of the integrated drive generator (IDG) failed on certain
Boeing Model 777 series airplanes. Specifically, the FAA received five
reports of IDG shaft failures. Investigation revealed problems with the
generator's hydraulic and mechanical systems.
Further, numerous failures of the backup generator have been
reported by operators. Investigation revealed that the pressure relief
valve in the backup generator may cause excessive fluctuation of the
oil-in pressure. This fluctuation may result in failure of the low oil
pressure switch, and consequent failure of the backup generator.
These conditions, if not corrected, could result in continued
degradation of the power system and consequent loss of electrical
power.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Service Bulletin 777-24-
0012, dated August 1, 1996, which describes procedures for replacing
the IDG with a unit having a different part number. Replacement of the
existing IDG with an IDG of improved design will reduce torque on the
IDG shaft and wear on the IDG fixed blocks.
The FAA also has reviewed and approved Boeing Service Bulletin 777-
24-0017, Revision 1, dated April 10, 1997, which describes procedures
for replacing the backup generator with a new backup generator.
Accomplishment of the actions specified in the service bulletins is
intended to adequately address the identified unsafe condition.
Explanation of Requirements of Proposed Rule
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 replacement of the IDG and the backup
generator with a new IDG and a new backup generator. The actions would
be required to be accomplished in accordance with the service bulletins
described previously.
Cost Impact
There are approximately 38 Boeing Model 777 series airplanes of the
affected design in the worldwide fleet. The FAA estimates that 22
airplanes of U.S. registry would be affected by this proposed AD, that
it would take approximately 18 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 $50,000 per airplane.
Based on these figures, the cost impact of the proposed AD on U.S.
operators is estimated to be $1,123,760, or $51,080 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.
Regulatory Impact
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. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
Boeing: Docket 97-NM-78-AD.
Applicability: Model 777 series airplanes equipped with Pratt &
Whitney engines and used in Extended Range Twin-Engine Operations
(ETOPS); as listed in Boeing Service Bulletins 777-24-0017, Revision
1, dated April 10, 1997, and 777-24-0012, dated August 1, 1996;
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 request approval for an
alternative method of compliance in accordance with paragraph (b) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or repair on the unsafe condition
addressed by this AD; and, if the unsafe condition has not been
eliminated, the request should include specific proposed actions to
address it.
Compliance: Required as indicated, unless accomplished
previously.
To prevent failure of the integrated drive generator (IDG) shaft
and the backup generator, which could result in continued
degradation of the power system and consequent loss of electrical
power, accomplish the following:
(a) Within 8 months after the effective date of this AD,
accomplish the requirements of paragraphs (a)(1) and (a)(2) of this
AD, as applicable.
(1) For airplanes identified in Boeing Service Bulletin 777-24-
0012, dated August 1, 1996: Replace the IDG with a new IDG in
accordance with Figure 1 or Figure 2 of the service bulletin, as
applicable.
(2) For airplanes identified in Boeing Service Bulletin 777-24-
0017, Revision 1, dated April 10, 1997: Replace the backup generator
and its engine wiring harness with new components in accordance with
the service bulletin.
(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, Seattle Aircraft Certification
Office (ACO). Operators shall submit their requests through an
appropriate FAA Principal Maintenance Inspector, who may add
comments and then send it to the Manager, Seattle ACO.
Note 2: Information concerning the existence of approved
alternative methods of
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compliance with this AD, if any, may be obtained from the Seattle
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 29, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 98-118 Filed 1-2-98; 8:45 am]
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