Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, and -900 Series Airplanes

[Federal Register Volume 71, Number 61 (Thursday, March 30, 2006)]
[Rules and Regulations]
[Pages 16019-16021]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-2958]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-20110; Directorate Identifier 2004-NM-114-AD; 
Amendment 39-14531; AD 2006-07-04]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, -700C, -
800, and -900 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Boeing Model 737-600, -700, -700C, -800, and -900 series 
airplanes. This AD requires repetitive general visual inspections for 
dirt, debris, and drain blockage and cleaning of the aft fairing 
cavities of the engine struts; and modification of the aft fairings, 
which terminates the repetitive general visual inspections. This AD 
results from a report indicating that water had accumulated in the 
cavities of the engine strut aft fairings. We are issuing this AD to 
prevent drain blockage by debris that, when combined with leaking, 
flammable fluid lines passing through the engine strut aft fairing, 
could allow flammable fluids to build up in the cavity of the aft 
fairing, and consequently could be ignited by the engine exhaust nozzle 
located below the engine strut, resulting in an explosion or 
uncontrolled fire.

DATES: This AD becomes effective May 4, 2006.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in the AD as of May 4, 2006.

ADDRESSES: You may examine the AD docket on the Internet at http://dms.dot.gov or in person at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street, SW., Nassif Building, 
room PL-401, Washington, DC.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for service information identified in this AD.

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:

Examining the Docket

    You may examine the airworthiness directive (AD) docket on the 
Internet at http://dms.dot.gov or in person at the Docket Management 
Facility office between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The Docket Management Facility office 
(telephone (800) 647-5227) is located on the plaza level of the Nassif 
Building at the street address stated in the ADDRESSES section.

Discussion

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 to include an AD that would apply to certain Boeing Model 
737-600, -700, -700C, -800, and -900 series airplanes. That NPRM was 
published in the Federal Register on January 24, 2005 (70 FR 3320). 
That NPRM proposed to require repetitive general visual inspections for 
dirt, debris, and drain blockage and cleaning of the aft fairing 
cavities of the engine struts; and modification of the aft fairings, 
which would terminate the repetitive general visual inspections.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments received.

Support for NPRM

    Southwest Airlines and AirTran Airways support the NPRM.

Request To Revise Dimension Between Certain Fastener Holes

    Alaska Airlines requests that we revise the dimension between 
certain fastener holes specified in Figures 3, 4, 5, and 6 of Boeing 
Special Attention Service Bulletin 737-54-1041, dated January 22, 2004. 
Alaska Airlines states that the dimension between an existing fastener 
hole and the new fastener hole is called out in the ten-thousandths 
(1.6772 inches); any deviation from this exact measurement would 
require approval of an alternative method of compliance (AMOC). Alaska 
Airlines suggests dimensions of 1.67 or 1.68 inches with a standard 
tolerance of <plus-minus>0.03 inch. If we cannot revise the dimension, 
the commenter instead requests that we clarify why such a tight 
tolerance would be required.
    We agree with Alaska Airlines' request, since there is no technical 
justification for requiring such a tight tolerance between fastener 
holes. Since issuance of the NPRM, Boeing has published Service 
Bulletin 737-54-1041, Revision 1, dated December 1, 2005. The 
procedures in Revision 1 of the service bulletin are essentially the 
same as those in the original issue, dated January 22, 2004, which we 
referenced in the NPRM as the appropriate source of service 
information. Revision 1 allows a dimension of 1.647 inches to 1.707 
inches between fastener holes. Therefore, we have revised this AD to 
also allow use of Revision 1 for accomplishing the actions specified in 
this AD. We have also revised paragraph (c) of this AD to reference 
Revision 1. Since the effectivity of Revision 1 is the same as the 
effectivity of the original issue, the applicability of this AD has not 
changed.

Clarification of AMOC Paragraph

    We have revised this action to clarify the appropriate procedure 
for notifying the principal inspector before using any approved AMOC on 
any airplane to which the AMOC applies.

Conclusion

    We have carefully reviewed the available data, including the 
comments received, and determined that air safety and the public 
interest require adopting the AD with the changes described previously. 
We have determined that these changes will neither increase the 
economic burden on any operator nor increase the scope of the AD.

[[Page 16020]]

Costs of Compliance

    This AD affects about 1,406 airplanes worldwide and about 549 U.S.-
registered airplanes. The following table provides the estimated costs 
for U.S. operators to comply with this AD.

                                                                     Estimated Costs
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                                                                                                                     Number of
                                                      Average                                                          U.S.-
                Action                  Work hours   labor rate            Parts              Cost per  airplane     registered         Fleet cost
                                                      per hour                                                       airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inspection, per inspection cycle.....            2          $65  None....................  $130, per inspection             549  $71,370, per inspection
                                                                                            cycle.                                cycle.
Modification.........................            5           65  $294....................  $619...................          549  $339,831.
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Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this AD will not have federalism 
implications under Executive Order 13132. This AD will 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.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866;
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); and
    (3) 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this AD and placed it in the AD docket. See the ADDRESSES 
section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

2006-07-04 Boeing: Amendment 39-14531. Docket No. FAA-2005-20110; 
Directorate Identifier 2004-NM-114-AD.

Effective Date

    (a) This AD becomes effective May 4, 2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-600, -700, -700C, -800, 
and -900 series airplanes, certificated in any category; as listed 
in Boeing Service Bulletin 737-54-1041, Revision 1, dated December 
1, 2005.

Unsafe Condition

    (d) This AD was prompted by a report indicating that water had 
accumulated in the cavities of the engine strut aft fairings. We are 
issuing this AD to prevent drain blockage by debris that, when 
combined with leaking, flammable fluid lines passing through the 
engine strut aft fairing, could allow flammable fluids to build up 
in the cavity of the aft fairing, and consequently could be ignited 
by the engine exhaust nozzle located below the engine strut, 
resulting in an explosion or uncontrolled fire.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Service Bulletin Reference

    (f) The term ``service bulletin,'' as used in this AD, means the 
Accomplishment Instructions of Boeing Special Attention Service 
Bulletin 737-54-1041, dated January 22, 2004; or Boeing Service 
Bulletin 737-54-1041, Revision 1, dated December 1, 2005.

Repetitive Inspections of the Engine Strut Aft Fairings

    (g) Within 4,000 flight cycles or within 30 months after the 
effective date of this AD, whichever occurs first: Do the actions 
specified in paragraphs (g)(1) and (g)(2) of this AD.
    (1) Do a general visual inspection for dirt, debris, and drain 
blockage and clean the aft fairing cavity of the left engine strut, 
in accordance with Part I of the service bulletin, except as 
provided by paragraph (h) of this AD. Thereafter at intervals not to 
exceed 4,000 flight cycles or 30 months, whichever occurs first: 
Repeat the inspection until the aft fairing of the left engine strut 
has been modified in accordance with paragraph (i)(1) of this AD.
    (2) Do a general visual inspection for dirt, debris, and drain 
blockage and clean the aft fairing cavity of the right engine strut, 
in accordance with Part II of the service bulletin, except as 
provided by paragraph (h) of this AD. Thereafter at intervals not to 
exceed 4,000 flight cycles or 30 months, whichever occurs first: 
Repeat the inspection until the aft fairing of the right engine 
strut has been modified in accordance with paragraph (i)(2) of this 
AD.

    Note 1: For the purposes of this AD, a general visual inspection 
is: ``A visual examination of an interior or exterior area, 
installation, or assembly to detect obvious damage, failure, or 
irregularity. This level of inspection is made from within touching 
distance unless otherwise specified. A mirror may be necessary to 
ensure visual access to all surfaces in the inspection area. This 
level of inspection is made under normally available lighting 
conditions such as daylight, hangar lighting, flashlight, or 
droplight and may require removal or opening of access panels or 
doors. Stands, ladders, or platforms may be required to gain 
proximity to the area being checked.''


[[Page 16021]]



Approved Equivalent Procedure

    (h) If the service bulletin specifies that the general visual 
inspection and cleaning of the aft fairing cavity of the left or 
right engine strut may be accomplished per an ``approved equivalent 
procedure'': The general visual inspection or cleaning must be 
accomplished in accordance with the chapter of the Boeing 737-600/
700/800/900 Airplane Maintenance Manual specified in the service 
bulletin.

Modification of the Engine Strut Aft Fairings

    (i) Within 9,000 flight cycles after the effective date of this 
AD, do the actions specified in paragraphs (i)(1) and (i)(2) of this 
AD.
    (1) Modify the aft fairing of the left engine strut, in 
accordance with Part III of the service bulletin; and after 
accomplishing the modification but before further flight, inspect 
and clean the drain system of the aft fairing in accordance with 
Part I of the service bulletin. This modification terminates the 
repetitive inspections required by paragraph (g)(1) of this AD.
    (2) Modify the aft fairing of the right engine strut, in 
accordance with Part IV of the service bulletin; and after 
accomplishing the modification but before further flight, inspect 
and clean the drain system of the aft fairing in accordance with 
Part II of the service bulletin. This modification terminates the 
repetitive inspections required by paragraph (g)(2) of this AD.

Alternative Methods of Compliance (AMOCs)

    (j)(1) The Manager, Seattle Aircraft Certification Office, FAA, 
has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) Before using any AMOC approved in accordance with 14 CFR 
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.

Material Incorporated by Reference

    (k) You must use Boeing Special Attention Service Bulletin 737-
54-1041, dated January 22, 2004; or Boeing Service Bulletin 737-54-
1041, Revision 1, dated December 1, 2005, to perform the actions 
that are required by this AD, unless the AD specifies otherwise. The 
Director of the Federal Register approved the incorporation by 
reference of these documents in accordance with 5 U.S.C. 552(a) and 
1 CFR part 51. Contact Boeing Commercial Airplanes, P.O. Box 3707, 
Seattle, Washington 98124-2207, for a copy of this service 
information. You may review copies at the Docket Management 
Facility, U.S. Department of Transportation, 400 Seventh Street, 
SW., room PL-401, Nassif Building, Washington, DC; on the Internet 
at http://dms.dot.gov; or at the National Archives and Records 
Administration (NARA). For information on the availability of this 
material at the NARA, call (202) 741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

    Issued in Renton, Washington, on March 17, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 06-2958 Filed 3-29-06; 8:45 am]
BILLING CODE 4910-13-P

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