[Federal Register Volume 65, Number 110 (Wednesday, June 7, 2000)]
[Proposed Rules]
[Pages 36095-36097]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-14315]


 ========================================================================
 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. 65, No. 110 / Wednesday, June 7, 2000 / 
Proposed Rules  

[[Page 36095]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-308-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 757 Series Airplanes 
Powered by Pratt & Whitney 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 757 series 
airplanes powered by Pratt & Whitney engines. This proposal would 
require modification of the nacelle strut and wing structure. This 
proposal is prompted by reports indicating that the actual operational 
loads applied to the nacelle are higher than the analytical loads that 
were used during the initial design. Such an increase in loading can 
lead to fatigue cracking in primary strut structure prior to an 
airplane reaching its design service objective. The actions specified 
by the proposed AD are intended to prevent fatigue cracking in primary 
strut structure and consequent reduced structural integrity of the 
strut.

DATES: Comments must be received by July 24, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-308-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: Dennis Stremick, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2776; 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 99-NM-308-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. 99-NM-308-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that the airplane 
manufacturer has accomplished a structural reassessment of the damage 
tolerance capabilities of the Boeing Model 757 series airplane powered 
by Pratt & Whitney engines. This reassessment indicates that the actual 
operational loads applied to the nacelle strut and wing structure are 
higher than the analytical loads that were used during the initial 
design. Subsequent analysis and service history, which includes 
numerous reports of fatigue cracking on certain strut and wing 
structure, indicate that fatigue cracking can occur on the primary 
strut structure before an airplane reaches its design service objective 
of 20 years or 50,000 flight cycles. Analysis also indicates that such 
cracking, if it were to occur, would grow at a much greater rate than 
originally expected. Fatigue cracking in primary strut structure would 
result in reduced structural integrity of the strut.

Explanation of Relevant Service Information

    Boeing recently has developed a modification of the strut-to-wing 
attachment structure installed on Model 757 series airplanes powered by 
Pratt & Whitney engines. This modification significantly improves the 
load-carrying capability and durability of the strut-to-wing 
attachments. Such improvement also will substantially reduce the 
possibility of fatigue cracking and corrosion developing in the 
attachment assembly.
    The FAA has reviewed and approved Boeing Service Bulletin 757-54-
0034, dated May 14, 1998, which describes procedures for modification 
of the nacelle strut and wing structure. The modification consists of 
replacing many of the significant load-bearing components of the strut 
(e.g., the side link fittings assemblies, the midspar fittings, the 
side load fittings, certain fuse bolt assemblies, etc.) with improved 
components.
    The service bulletin contains a formula for calculating an optional 
compliance threshold for the specified modification. This formula is 
intended to be used as an alternative to the 20-year calendar threshold 
specified in the service bulletin.
    In addition, Table I of the service bulletin also identifies two 
related service bulletin modifications that must be accomplished before 
or at the same time as the modification in Boeing Service Bulletin 757-
54-0034:

[[Page 36096]]

     Boeing Service Bulletin 757-54-0027: The FAA has reviewed 
and approved Boeing Service Bulletin 757-54-0027, Revision 1, dated 
October 27, 1994, which describes procedures for visual and eddy 
current inspections of the fuse pins of the diagonal brace and upper 
link, and installation of new 15-5PH fuse pins and new shoulder bolts 
for the diagonal brace and upper link.
     Boeing Service Bulletin 757-54-0036: The FAA has reviewed 
and approved Boeing Service Bulletin 757-54-0036, dated May 14, 1998, 
which describes procedures for replacement of the upper link with a 
new, improved part that will increase the strength and durability of 
the upper link installation. That service bulletin also describes 
procedures for modification of a wire support bracket attached to the 
upper link.
    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 accomplishment of the actions specified in 
the service bulletins described previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletin

    Operators should note that, although Boeing Service Bulletin 757-
54-0034 specifies that the manufacturer may be contacted for 
disposition of certain damage conditions that may detected during 
accomplishment of the modification, this proposal would require the 
repair of those conditions to be accomplished in accordance with a 
method approved by the FAA.

Cost Impact

    There are approximately 317 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 278 airplanes of U.S. registry 
would be affected by this proposed AD.
    It would take approximately 800 work hours per airplane to 
accomplish the proposed modification of the nacelle strut and wing 
structure described in Boeing Service Bulletin 757-54-0034, dated May 
14, 1998, at an average labor rate of $60 per work hour. Required parts 
would be provided at no cost by the airplane manufacturer. Based on 
these figures, the cost impact of this proposed modification on U.S. 
operators is estimated to be $13,344,000, or $48,000 per airplane.
    It would take approximately 26 work hours per airplane to 
accomplish the actions described in Boeing Service Bulletin 757-54-
0027, Revision 1, at an average labor rate of $60 per work hour. 
Required parts would be provided at no cost by the airplane 
manufacturer. Based on these figures, the cost impact of these proposed 
actions on U.S. operators is estimated to be $433,680, or $1,560 per 
airplane.
    It would take approximately 90 work hours per airplane to 
accomplish the actions described in Boeing Service Bulletin 757-54-
0036, at an average labor rate of $60 per work hour. Required parts 
would be provided at no cost by the airplane manufacturer. Based on 
these figures, the cost impact of these proposed actions on U.S. 
operators is estimated to be $1,501,200, or $5,400 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 99-NM-308-AD.

    Applicability: Model 757 series airplanes powered by Pratt & 
Whitney engines, line numbers 1 through 735 inclusive, 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 (d) 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 fatigue cracking in primary strut structure and 
consequent reduced structural integrity of the strut, accomplish the 
following:

Modifications

    (a) Modify the nacelle strut and wing structure on both the left 
and right sides of the airplane, in accordance with Boeing Service 
Bulletin 757-54-0034, dated May 14, 1998, at the later of the times 
specified in paragraph (a)(1) or (a)(2) of this AD.
    (1) Prior to the accumulation of 37,500 total flight cycles, or 
within 20 years since the date of manufacture, whichever occurs 
first. Use of the optional threshold formula described in paragraph 
I.D. of the service bulletin is an acceptable alternative to the 20-
year threshold.
    (2) Within 3,000 flight cycles after the effective date of this 
AD.
    (b) Prior to or concurrently with the accomplishment of the 
modification of the nacelle strut and wing structure required by 
paragraph (a) of this AD; as specified in paragraph I.D., Table I, 
``Strut Improvement Bulletins,'' on page 5 of Boeing Service 
Bulletin 757-54-0034, dated May 14, 1998; accomplish the actions 
specified in Boeing Service Bulletin 757-54-0027, Revision 1,

[[Page 36097]]

dated October 27, 1994, and Boeing Service Bulletin 757-54-0036, 
dated May 14, 1998, as applicable, in accordance with those service 
bulletins.
    (c) If any damage to airplane structure is found during the 
accomplishment of the modification required by paragraph (a) of this 
AD; and the service bulletin specifies to contact Boeing for 
appropriate action: Prior to further flight, repair in accordance 
with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA, Transport Airplane Directorate. For 
a repair method to be approved by the Manager, Seattle ACO, as 
required by this paragraph, the Manager's approval letter must 
specifically reference this AD.

Alternative Methods of Compliance

    (d) 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 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 compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (e) 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 June 1, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-14315 Filed 6-6-00; 8:45 am]
BILLING CODE 4910-13-P