[Federal Register Volume 63, Number 97 (Wednesday, May 20, 1998)]
[Proposed Rules]
[Pages 27685-27687]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-13405]
========================================================================
Proposed Rules
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
========================================================================
Federal Register / Vol. 63, No. 97 / Wednesday, May 20, 1998 /
Proposed Rules
[[Page 27685]]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 97-NM-89-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747-400 Series Airplanes
Powered by Pratt and Whitney PW4000 Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: This document proposes the adoption of a new airworthiness
directive (AD) that is applicable to certain Boeing Model 747-400
series airplanes. This proposal would require repetitive inspections to
detect improper installation and fatigue damage of the end cap of the
forward engine mount, and replacement of the forward engine mount end
cap assembly with an improved end cap assembly. Such replacement, when
accomplished, would terminate the repetitive inspections. This proposal
is prompted by a report of fatigue cracking of end cap bolts, caused by
improper installation. Subsequent investigation revealed that properly
installed end caps also are subject to early fatigue cracking. The
actions specified by the proposed AD are intended to prevent failure of
the end cap assembly, which could lead to separation of the engine from
the airplane in the event of a primary thrust linkage failure.
DATES: Comments must be received by July 6, 1998.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-114,
Attention: Rules Docket No. 97-NM-89-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: Tamara L. Anderson, Aerospace
Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue,
SW., Renton, Washington 98055-4056; telephone (425) 227-2771; 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 Number 97-NM-89-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-114, Attention: Rules
Docket No. 97-NM-89-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
The FAA has received a report of broken end cap bolts of the
forward engine mount, which were found during overhaul of a Pratt &
Whitney PW4000 engine that had been installed on a Boeing Model 747-400
series airplane. Investigation revealed that the end cap had been
installed backwards. A properly installed end cap does not normally
react any significant engine thrust loads; it is intended to provide a
secondary load path if the primary thrust linkage fails. An end cap
installed backwards will react the engine thrust loads along with the
primary thrust linkage, which will result in premature fatigue failure
of the end cap or end cap bolts. In addition, fatigue analysis and
testing have confirmed that a properly installed end cap assembly would
fail in a low number of flight cycles after a primary thrust linkage
failure. Failure of the end cap assembly, if not corrected, could lead
to separation of the engine from the airplane in the event of primary
thrust linkage failure.
Other Relevant Rulemaking
There is a high degree of similarity between the configurations of
the engine installations on the incident airplane (Model 747-400) and
certain Model 767 series airplanes. The FAA may consider rulemaking to
address this condition on Model 767 series airplanes; therefore, this
proposed rule is applicable only to Model 747-400 series airplanes.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Alert Service Bulletin
747-71A2283, dated October 10, 1996, which describes procedures for
repetitive detailed visual inspections to detect improper installation
and fatigue damage of the end cap of the forward engine mount, and
replacement of the end cap assembly of the forward engine mount with an
improved assembly. Such replacement would eliminate the need for the
repetitive inspections. Accomplishment of this replacement, as
described in the alert service bulletin, is intended to adequately
address the identified unsafe condition.
[[Page 27686]]
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 accomplishment of the actions specified in
the alert service bulletin described previously, except as discussed
below.
Differences Between Proposed Rule and Service Bulletin
Boeing Alert Service Bulletin 747-71A2283 divides the affected
airplanes into two groups depending upon the particular engine
configuration of the affected airplane, and provides different
procedures depending upon group classification and engine on-wing
flight cycles. Operators should note that, whereas the alert service
bulletin specifies that operators of Group 1 airplanes should contact
the manufacturer for disposition of the terminating action, this
proposed AD would require that the end cap and bolts be replaced in
accordance with the procedures specified in Chapter 71-00-00 of the
Boeing 747 Airplane Maintenance Manual (AMM).
Additionally, the alert service bulletin specifies that certain
actions required by this proposed AD may be accomplished in accordance
with ``an operator's equivalent procedure.'' However, this proposed AD
requires that those actions be accomplished in accordance with the
procedures specified in Chapter 71-00-00 of the AMM. An ``operator's
equivalent procedure'' may be used only if approved as an alternative
method of compliance in accordance with paragraph (e) of this proposed
AD.
Cost Impact
There are approximately 133 airplanes of the affected design in the
worldwide fleet. The FAA estimates that 36 airplanes of U.S. registry
would be affected by this proposed AD: 35 Group 1 airplanes, and 1
Group 2 airplane.
It would take approximately 36 work hours per Group 1 airplane (9
work hours per engine) to accomplish the proposed inspection, at an
average labor rate of $60 per work hour. Based on these figures, the
cost impact of this proposed inspection on U.S. operators is estimated
to be $75,600, or $2,160 per airplane, per inspection cycle.
It would take approximately 272 work hours per airplane (68 work
hours per engine) for both Group 1 and Group 2 airplanes to accomplish
the proposed replacement of the forward engine mount end cap and/or end
cap bolts, at an average labor rate of $60 per work hour. Required
parts would cost approximately $1,000 per airplane. Based on these
figures, the cost impact of this proposed replacement on U.S. operators
is estimated to be $623,520, or $17,320 per airplane.
The cost impact figures discussed above are 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-89-AD.
Applicability: Model 747-400 series airplanes powered by Pratt &
Whitney PW4000 engines, as listed in Boeing Alert Service Bulletin
747-71A2283, dated October 10, 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
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 (e) 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 possible separation of the engine from the airplane
in the event of a primary thrust linkage failure, accomplish the
following:
(a) For Group 1 airplanes, as identified in Boeing Alert Service
Bulletin 747-71A2283, dated October 10, 1996: Except as provided by
paragraph (c) of this AD, accomplish paragraphs (a)(1) and (a)(2),
of this AD, as applicable, in accordance with the alert service
bulletin.
(1) Within 500 hours time-in-service after the effective date of
this AD, perform a detailed visual inspection (Work Package 1) to
detect improper installation of the end cap of the forward engine
mount, in accordance with the alert service bulletin.
(i) If no attachment hardware is found loose or missing, and if
no part shows signs of damage, repeat the inspection thereafter at
intervals not to exceed 5,000 hours time-in-service or 15 months,
whichever occurs first, until the requirements of paragraph (a)(2)
of this AD have been accomplished.
(ii) If any attachment hardware is found loose or missing, or if
any part shows signs of damage, prior to further flight, replace the
end cap and bolts with an improved end cap and bolts (Work Package
2), in accordance with the alert service bulletin. Accomplishment of
the replacement constitutes terminating action for the requirements
of this AD for Group 1 airplanes.
(2) Replace the existing end cap and end cap bolts of the
forward engine mount with an improved end cap and end cap bolts
(Work Package 2), at the earlier of the times specified in
paragraphs (a)(2)(i) and (a)(2)(ii) of this AD. Accomplishment of
the replacement constitutes terminating action for the requirements
of this AD for Group 1 airplanes.
(i) Prior to the accumulation of 16,000 total flight cycles on
any engine, or within 500
[[Page 27687]]
hours time-in-service after the effective date of this AD, whichever
occurs later; or
(ii) Within 3 years after the effective date of this AD.
(b) For Group 2 airplanes, as identified in Boeing Alert Service
Bulletin 747-71A2283, dated October 10, 1996: Except as provided by
paragraph (c) of this AD, within 3 years after the effective date of
this AD, replace the existing end cap bolts of the forward engine
mount with improved end cap bolts (Work Package 3), in accordance
with the alert service bulletin.
(c) Where Boeing Alert Service Bulletin 747-71A2283, dated
October 10, 1996, specifies that the actions required by this AD may
be accomplished in accordance with an ``operator's equivalent
procedure,'' the actions must be accomplished in accordance with
Chapter 71-00-00 of the Boeing 747 Airplane Maintenance Manual
(AMM), as specified in the alert service bulletin.
(d) As of the effective date of this AD, no person shall install
on any airplane a forward engine mount end cap having part number
310T3026-1.
(e) 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), 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, Seattle ACO.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(f) 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 May 14, 1998.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 98-13405 Filed 5-19-98; 8:45 am]
BILLING CODE 4910-13-U
