[Federal Register Volume 69, Number 95 (Monday, May 17, 2004)]
[Proposed Rules]
[Pages 27866-27868]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-11041]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-NM-252-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 757 Series 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 Boeing Model 757 series 
airplanes. This proposal would require repetitive detailed inspections 
of the support brackets and associated fasteners for the hydraulic 
lines located in the nacelle struts, and related investigative and 
corrective actions as necessary. This proposal also provides an 
optional terminating action for the repetitive inspections. This action 
is necessary to prevent flammable fluids from leaking into the interior 
compartment of the nacelle struts where ignition sources exist, which 
could result in the ignition of flammable fluids and an uncontained 
fire. This action is intended to address the identified unsafe 
condition.

DATES: Comments must be received by July 1, 2004.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2003-NM-252-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2003-NM-252-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 or 2000 or 
ASCII text.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplanes, 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: Tom Thorson, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 917-6508; fax (425) 917-6590.

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 action may be changed in 
light of the comments received.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
     For each issue, state what specific change to the proposed 
AD is being requested.
     Include justification (e.g., reasons or data) for each 
request.
    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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2003-NM-252-AD.'' The postcard will be date stamped 
and returned to the commenter.

[[Page 27867]]

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. 2003-NM-252-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports of failure of the support brackets and 
associated fasteners for the hydraulic lines located in the nacelle 
struts. These failures occurred on certain Model 757 series airplanes 
equipped with Rolls-Royce engines. The hydraulic lines provide supply 
pressure from the hydraulic pumps to the airframe and are subject to 
high frequency pressure oscillations/vibrations. Investigation by the 
manufacturer revealed that the operating pressure and surge loads from 
the hydraulic pumps are higher than originally expected and exceed the 
capability of the design for the support bracket structure.
    The hydraulic lines are located in the upper fairing compartment of 
the nacelle struts. The upper fairing compartment is a flammable 
leakage zone and is isolated from other strut compartments by a 
protective vapor barrier. The vapor barrier acts as a seal to keep 
flammable fluids and vapors from hydraulic and fuel line leaks out of 
the interior portion of the strut where pneumatic bleed air ducts are 
located. The surface temperature of the bleed air ducts is hot enough 
to be an ignition source. The reported condition of sheared or loose 
fasteners, or damage to the strut webs adjacent to the support brackets 
and associated fasteners, compromises the vapor barrier, which allows 
flammable fluids to leak into the interior compartments of the nacelle 
struts. Such a condition, if not corrected, could result in ignition of 
flammable fluids and an uncontained fire.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletins 
757-54A0045 (for Model 757-200 series airplanes), dated May 22, 2003; 
and 757-54A0046 (for Model 757-300 series airplanes), dated May 29, 
2003. These service bulletins describe procedures for inspecting the 
support brackets and associated fasteners for the hydraulic lines 
located in the nacelle struts for loose and/or damaged parts, and 
related investigative and corrective actions. Evidence of damage 
includes sheared fasteners and/or elongated fastener holes in the strut 
webs. If no damaged or loose parts are found, the service bulletins 
state that operators may either repeat the inspection of the hydraulic 
line support brackets and associated fasteners at the intervals 
specified in the service bulletin, or do the related investigative and 
corrective actions.
    The procedures for the related investigative and corrective actions 
include:
     Inspecting the fuel and hydraulic lines and strut webs for 
evidence of damage (e.g., chafing or holes) caused by a loose support 
bracket and/or line.
     Replacing or repairing damaged fuel lines.
     Replacing damaged hydraulic lines.
     Repairing damaged areas of the strut webs.
     Contacting Boeing for damage that is beyond the repair 
limitations specified in the structural repair manual.
     Modifying the support brackets by installing additional 
straps and stronger fasteners.
    Accomplishment of the actions specified in the service bulletins is 
intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed AD

    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. 
This proposed AD also would provide for optional terminating action for 
the repetitive inspections.

Difference Between the Service Bulletins and Proposed AD

    Although the service bulletins specify that operators may contact 
the manufacturer for disposition of certain repair conditions, this 
proposed AD would require operators to repair those conditions per a 
method approved by the FAA.

Cost Impact

    There are approximately 603 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 325 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
22 work hours per airplane to accomplish the proposed inspections, and 
that the average labor rate is $65 per work hour. Based on these 
figures, the cost impact of the proposed AD on U.S. operators is 
estimated to be $464,750, or $1,430 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 proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include incidental costs, such as the 
time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.

Regulatory Impact

    The regulations proposed herein would not have a substantial direct 
effect 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, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    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 2003-NM-252-AD.


[[Page 27868]]


    Applicability: Model 757 series airplanes, line numbers 1 
through 1018 inclusive, equipped with Rolls Royce engines; 
certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent flammable fluids from leaking into the interior 
compartment of the nacelle struts where ignition sources exist, 
which could result in the ignition of flammable fluids and an 
uncontained fire, accomplish the following:

Inspection

    (a) Within 3,000 flight hours after the effective date of this 
AD: Do a detailed inspection of the support brackets and associated 
fasteners for the hydraulic lines located in the nacelle struts for 
loose and/or damaged parts, by accomplishing all of the actions 
specified in Part 1 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 757-54A0045 (for Model 757-200 series 
airplanes), dated May 22, 2003; or Boeing Alert Service Bulletin 
757-54A0046 (for Model 757-300 series airplanes), dated May 29, 
2003; as applicable. Do the actions per the applicable service 
bulletin. Repeat the inspection thereafter at intervals not to 
exceed 3,000 flight hours.

    Note 1: For the purposes of this AD, a detailed inspection is 
defined as: ``An intensive visual examination of a specific 
structural area, system, installation, or assembly to detect damage, 
failure, or irregularity. Available lighting is normally 
supplemented with a direct source of good lighting at intensity 
deemed appropriate by the inspector. Inspection aids such as mirror, 
magnifying lenses, etc., may be used. Surface cleaning and elaborate 
access procedures may be required.''

Related Investigative and Corrective Actions

    (b) Except as required by paragraph (d) of this AD: If any loose 
or damaged parts are found during any inspection required by 
paragraph (a) of this AD, before further flight, do all of the 
related and investigative corrective actions specified in Part 2 of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
757-54A0045 (for Model 757-200 series airplanes), dated May 22, 
2003; or Boeing Alert Service Bulletin 757-54A0046 (for Model 757-
300 series airplanes), dated May 29, 2003; as applicable. Do the 
actions per the applicable service bulletin. Accomplishment of these 
actions constitutes terminating action for the repetitive 
inspections required by paragraph (a) of this AD.

Optional Terminating Action

    (c) Accomplishment of all of the actions specified in Part 2 of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
757-54A0045 (for Model 757-200 series airplanes), dated May 22, 
2003; or Boeing Alert Service Bulletin 757-54A0046 (for Model 757-
300 series airplanes), dated May 29, 2003; as applicable; 
constitutes terminating action for the repetitive inspections 
required by paragraph (a) of this AD.

Repair Information

    (d) If any damage is found during any inspection required by 
this AD, and the service bulletin specifies contacting Boeing for 
appropriate action: Before further flight, repair per a method 
approved by the Manager, Seattle Aircraft Certification Office 
(ACO), FAA. For a repair method to be approved by the Manager, 
Seattle ACO, as required by this paragraph, the Manager's approval 
letter must specifically refer to this AD.

Alternative Methods of Compliance

    (e) In accordance with 14 CFR 39.19, the Manager, Seattle ACO, 
is authorized to approve alternative methods of compliance (AMOCs) 
for this AD.


    Issued in Renton, Washington, on May 5, 2004.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-11041 Filed 5-14-04; 8:45 am]
BILLING CODE 4910-13-P