[Federal Register Volume 69, Number 85 (Monday, May 3, 2004)]
[Proposed Rules]
[Pages 24101-24103]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-9902]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2003-NM-106-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, -700C, -
800, and -900 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 737-600, -
700, -700C, -800, and -900 series airplanes. This proposal would 
require a general visual inspection for sealant at the interface 
between the diagonal brace fitting and the aft bulkhead and at the four 
bolts common to the interface. It would also require applying sealant 
if none is present or if it is not continuous. This action is necessary 
to prevent flammable fluid in the upper or rear pylon areas from 
leaking past unsealed areas and onto a hot engine nozzle, which could 
result in ignition of the fluid, causing an undetected and 
uncontrollable fire to spread into the engine struts. This action is 
intended to address the identified unsafe condition.

DATES: Comments must be received by June 17, 2004.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2003-NM-106-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-106-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: Doug Pegors, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 917-6504; 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-106-AD.'' The postcard will be date stamped 
and returned to the commenter.

[[Page 24102]]

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-106-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received reports indicating that the fay sealing at the 
interface between the diagonal brace fitting and aft bulkhead in both 
engine struts and the wet installation of four bolts common to the 
interface may not have been completed during production of certain 
Boeing Model 737-600, -700, -00C, -800, and -900 series airplanes. This 
area is a flammable leakage zone and requires sealing of all openings 
that could provide a path to an ignition source. Incomplete sealing, if 
not corrected, could allow flammable fluid in the upper or rear pylon 
areas to leak past unsealed areas and onto a hot engine nozzle, which 
could result in ignition of the fluid, causing an undetected and 
uncontrollable fire to spread into the engine struts.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Special Attention Service 
Bulletin 737-54-1039, Revision 1, dated October 10, 2002, which 
describes procedures for the following actions:
    1. A general visual inspection to determine whether the diagonal 
brace fitting and aft bulkhead has been fay sealed or fillet sealed to 
the aft bulkhead and to determine whether the four bolts have been wet 
installed or cap sealed.
    2. Application of fillet seal, if the seal is not present or not 
continuous. Accomplishment of the actions specified in the service 
bulletin 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 bulletin described previously.

Cost Impact

    There are approximately 946 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 436 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
2 work hours per airplane to accomplish the proposed actions, 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 
$56,680, or $130 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. Manufacturer warranty 
remedies may be available for labor costs associated with this proposed 
AD. As a result, the costs attributable to the proposed AD may be less 
than stated above.

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-106-AD.

    Applicability: Model 737-600, -700, -700C, -800, and -900 series 
airplanes, line numbers 1 through 946 inclusive; certificated in any 
category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent flammable fluid in the upper or rear pylon areas from 
leaking past unsealed areas and onto a hot engine nozzle, which 
could result in ignition of the fluid, causing an undetected and 
uncontrollable fire to spread into the engine struts; accomplish the 
following:

Inspection of Sealant

    (a) Within 18 months or 3,500 flight cycles after the effective 
date of this AD, whichever occurs first: Perform a general visual 
inspection for sealant at the interface of the diagonal brace 
fitting and the aft bulkhead and at the four bolts common to the 
interface, in accordance with the Accomplishment Instructions of 
Boeing Special Attention Service Bulletin 737-54-1039, Revision 1, 
dated October 10, 2002.
    (1) If the findings of the general visual inspection are as 
described in paragraphs (a)(1)(i) and (a)(1)(ii) of this AD, then no 
further action is required by this AD.
    (i) The seal is continuous or there is evidence of fay seal 
sqeeze out present.
    (ii) The bolts have evidence of sealant squeeze out or a cap 
seal exists.

Application of Fillet Seal and Cap Seal

    (2) If the findings of the general visual inspection are as 
described in paragraphs (a)(2)(i) and/or (a)(2)(ii) of this AD, 
before further flight: Fillet seal around the interface of the 
diagonal brace fitting and the aft bulkhead; and/or cap seal the 
four bolts common to the interface; as applicable; in accordance 
with the Accomplishment Instructions of Boeing Special Attention 
Service Bulletin 737-54-1039, Revision 1, dated October 10, 2002.
    (i) The seal is not continuous and there is no evidence of fay 
seal squeeze out present.
    (ii) The bolts do not have evidence of sealant squeeze out and 
no cap seal exists.

Credit for Actions Accomplished per Previous Service Bulletin

    (b) Actions accomplished before the effective date of this AD 
per Boeing Special Attention Service Bulletin 737-54-1039, dated 
June 13, 2002, are acceptable for compliance with the corresponding 
actions of paragraph (a) of this AD.

Alternative Methods of Compliance

    (c) In accordance with 14 CFR 39.19, the Manager, Seattle 
Aircraft Certification Office

[[Page 24103]]

(ACO), FAA, is authorized to approve alternative methods of 
compliance for this AD.

    Issued in Renton, Washington, on April 21, 2004.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-9902 Filed 4-30-04; 8:45 am]
BILLING CODE 4910-13-P