[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]


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 Proposed Rules
                                                 Federal Register
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 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.
 
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 

  Federal Register / Vol. 63, No. 97 / Wednesday, May 20, 1998 / 
Proposed Rules  

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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).

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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.

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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

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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