[Federal Register: July 8, 2008 (Volume 73, Number 131)]
[Rules and Regulations]
[Page 38885-38887]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr08jy08-2]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2007-0395; Directorate Identifier 2007-NM-157-AD;
Amendment 39-15588; AD 2008-13-25]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-300 and -400 Series
Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: We are adopting a new airworthiness directive (AD) for certain
Boeing Model 737-300 and -400 series airplanes. This AD requires
testing and inspecting a certain web panel of the main wheel well
pressure deck to determine the material type and thickness; and related
investigative and corrective actions if necessary. This AD results from
several reports indicating that cracks ranging from 0.8 to 8.0 inches
long were found on a certain web panel of the main wheel well pressure
deck. We are issuing this AD to prevent fatigue cracking in the web
panel of the main wheel well pressure deck, which could result in
venting and consequent decompression of the airplane.
DATES: This AD is effective August 12, 2008.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of August 12,
2008.
ADDRESSES: For service information identified in this AD, contact
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-
2207.
Examining the AD Docket
You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility
between 9 a.m. and 5 p.m., Monday through Friday, except Federal
holidays. The AD docket contains this AD, the regulatory evaluation,
any comments received, and other information. The address for the
Docket Office (telephone 800-647-5527) is the Document Management
Facility, U.S. Department of Transportation, Docket Operations, M-30,
West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE.,
Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT: Wayne Lockett, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office,
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425)
917-6447; fax (425) 917-6590.
SUPPLEMENTARY INFORMATION:
Discussion
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR
part 39 to include an airworthiness directive (AD) that would apply to
certain Boeing Model 737-300 and -400 series airplanes. That NPRM was
published in the Federal Register on January 10, 2008 (73 FR 1846).
That NPRM proposed to require testing and inspecting a certain web
panel of the main wheel well pressure deck to determine the material
type and thickness; and related investigative and corrective actions if
necessary.
Comments
We gave the public the opportunity to participate in developing
this AD. We considered the comments received.
Request To Change the Description of the Unsafe Condition
Boeing asks that the unsafe condition (end level effect) specified
in the applicable sections of the NPRM be changed from ``rapid
decompression'' to ``controlled decompression.'' Boeing states that the
most probable result of the cracking would be pressure loss or
controlled depressurization. Boeing has received reports of cracks
ranging from 4.5 to 8 inches in the web panel of the main wheel well
pressure deck; the reports included the following data:
Cabin crews reported a loud hissing noise coming from the
area below seats 14A, B, and C. No depressurization was reported.
The crew reported a loud hissing noise from the cabin
lining on the left-hand side at row 15. The cabin windows along the
left-hand side progressively frosted up until, after about 2 hours, all
the windows were frosted up between rows 11 through 17.
It was reported that it was not possible to pressurize
another airplane.
We partially agree with Boeing. We agree to change the end level
effect of the unsafe condition by removing the word ``rapid,'' since
Boeing has provided data verifying that the decompression does not
happen quickly. However, we do not agree that
[[Page 38886]]
the decompression is ``controlled'' because of the safety implications
and consequences associated with cracking on a web panel of the main
wheel well pressure deck. We have changed the applicable sections in
this AD accordingly.
Request To Clarify Certain Compliance Times
Boeing asks that we clarify the different compliance times for
replacing discrepant web panels, depending on the thickness, as
specified in Table 1 of Part 1.E., Compliance, of Boeing Special
Attention Service Bulletin 737-57-1289, dated June 13, 2007. (The
service bulletin was referenced in the NPRM as the appropriate source
of service information for accomplishing the specified actions.) Boeing
states that, as written, paragraphs (g)(1) and (g)(2) of the NPRM would
allow 30 months or 6,000 flight cycles, whichever is later, to replace
discrepant web panels. Boeing notes that this is acceptable for
discrepant web panels with a material thickness that is found to be
greater than or equal to 0.037 inch, and less than 0.047 inch; however,
for web panels with a material thickness of less than 0.037 inch the
specified compliance time is before further flight. Boeing adds that
web panels with a material thickness of less than 0.037 inch do not
meet the ultimate regulatory load requirements. Boeing also asks that
the related investigative and corrective actions be clarified.
We agree with Boeing that some clarification is necessary.
Paragraph (g)(1) of the AD requires accomplishing all applicable
related investigative and corrective actions before further flight
(which includes replacing any discrepant web panels) by doing all the
actions specified in the Accomplishment Instructions of the service
bulletin. The Accomplishment Instructions do not clearly identify web
panels with a material thickness of less than 0.037 inch; however, the
web panels are clearly identified in paragraph 1.E. of the service
bulletin. Paragraph 1.E. specifies replacing web panels with a material
thickness of less than 0.037 inch, as specified in paragraph 3.B.7. of
the Accomplishment Instructions of the service bulletin. Therefore, we
have clarified paragraph (g)(1) of this AD to add that the corrective
actions include replacing any web panel with a material thickness of
less than 0.037 inch before further flight. We have also changed
paragraph (g)(2) of this AD to clarify that the compliance time in that
paragraph is separate from the compliance time specified in paragraph
(g)(1). The related investigative and corrective actions are defined in
the service information section of the NPRM; therefore, no change is
necessary in this regard.
Request To Clarify That Additional Action Is Necessary
Boeing also asks that we change paragraph (e) of the NPRM to
clarify that additional action is necessary for operators that
inspected web panels using instructions that were contained in Boeing
Communication messages that were sent out on January 17, 2006, prior to
the release of the referenced service bulletin. Boeing states that the
messages were sent to airlines that were operating airplanes that could
have a discrepant web panel. Boeing adds that following release of
those messages, as part of the information being developed for release
in the referenced service bulletin, it was determined that additional
details were necessary to accurately define the instructions to inspect
for discrepant web panels. Boeing notes that the additional details,
which affect both the chemical spot test and the ultrasonic thickness
inspections, have been included in the service bulletin referenced in
the NPRM as the source of service information for doing the specified
actions; therefore, inspections accomplished without these additional
steps could result in incorrect identification of discrepant web
panels. Boeing also suggests that this language be added to paragraph
(e) of the AD.
We acknowledge Boeing's concerns; however, paragraph 1.E,
``Compliance,'' of the referenced service bulletin specifies that the
inspection instructions contained in the subject Boeing messages sent
out on January 17, 2006, did not include certain steps. That section
specifies that the chemical spot test and ultrasonic thickness
inspections must be done again by following the procedures in the
referenced service bulletin. In addition, paragraph (e) of this AD
states that if the actions required by this AD have been done
previously, they do not need to be done again. Therefore, we have made
no change to the AD in this regard.
Conclusion
We reviewed the relevant data, considered the comments received,
and determined that air safety and the public interest require adopting
the AD with the changes described previously. We also determined that
these changes will not increase the economic burden on any operator or
increase the scope of the AD.
Costs of Compliance
There are about 31 airplanes of the affected design in the
worldwide fleet. This AD affects 1 airplane of U.S. registry. The
required tests and inspections take about 3 work hours per airplane, at
an average labor rate of $80 per work hour. Based on these figures, the
estimated cost of the AD for this U.S. operator is $240.
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
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.
You can find our regulatory evaluation and the estimated costs of
compliance in the AD Docket.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
[[Page 38887]]
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 FAA amends Sec. 39.13 by adding the following new AD:
2008-13-25 Boeing: Amendment 39-15588. Docket No. FAA-2007-0395;
Directorate Identifier 2007-NM-157-AD.
Effective Date
(a) This airworthiness directive (AD) is effective August 12,
2008.
Affected ADs
(b) None.
Applicability
(c) This AD applies to Boeing Model 737-300 and -400 series
airplanes, certificated in any category; as identified in Boeing
Special Attention Service Bulletin 737-57-1289, dated June 13, 2007.
Unsafe Condition
(d) This AD results from several reports indicating that cracks
ranging from 0.8 to 8.0 inches long were found on a certain web
panel of the main wheel well pressure deck. We are issuing this AD
to prevent fatigue cracking in the web panel of the main wheel well
pressure deck, which could result in venting and consequent
decompression of the airplane.
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.
Testing/Inspecting/Investigative and Corrective Actions
(f) Within 6 months after the effective date of this AD: Do a
test of the web panel of the main wheel well pressure deck to
determine the material type, and do an ultrasonic inspection to
determine material thickness, by doing all the applicable actions
specified in the Accomplishment Instructions of Boeing Special
Attention Service Bulletin 737-57-1289, dated June 13, 2007.
(g) For airplanes on which the web thickness or material is
found to be discrepant during the test and inspection required by
paragraph (f) of this AD, accomplish the applicable actions
specified in paragraphs (g)(1) and (g)(2) of this AD at the time
specified, in accordance with Boeing Special Attention Service
Bulletin 737-57-1289, dated June 13, 2007.
(1) Except as provided by paragraph (h) of this AD: Do all
applicable related investigative and corrective actions (including
detailed and general visual inspections) before further flight, by
doing all the actions specified in the Accomplishment Instructions
of the service bulletin. Repeat the inspections thereafter at
intervals not to exceed 1,000 flight cycles until the actions
required by paragraph (g)(2) of this AD have been done. For any web
panel with a material thickness of less than 0.037 inch, replace the
web panel before further flight, in accordance with paragraph 3.B.7.
of the Accomplishment Instructions of the service bulletin. Doing
this replacement ends the repetitive inspections required by this
paragraph.
(2) Except as required by paragraph (g)(1) of this AD: Within 30
months or 6,000 flight cycles after accomplishing the actions
required by paragraph (g)(1) of this AD, whichever is later, replace
the web panel in accordance with the Accomplishment Instructions of
the service bulletin. Doing this replacement ends the repetitive
inspections required by paragraph (g)(1) of this AD.
Corrective Actions
(h) If any crack or corrosion is found during any inspection
required by paragraph (g)(1) of this AD, and Boeing Special
Attention Service Bulletin 737-57-1289, dated June 13, 2007,
specifies to contact Boeing for repair instructions: Before further
flight, repair according to a method approved in accordance with the
procedures specified in paragraph (i) of this AD.
Alternative Methods of Compliance (AMOCs)
(i)(1) The Manager, Seattle Aircraft Certification Office (ACO),
has the authority to approve AMOCs for this AD, if requested in
accordance with the procedures found in 14 CFR 39.19.
(2) To request a different method of compliance or a different
compliance time for this AD, follow the procedures in 14 CFR 39.19.
Before using any approved AMOC on any airplane to which the AMOC
applies, notify your appropriate principal inspector (PI) in the FAA
Flight Standards District Office (FSDO), or lacking a PI, your local
FSDO.
(3) An AMOC that provides an acceptable level of safety may be
used for any repair required by this AD, if it is approved by an
Authorized Representative for the Boeing Commercial Airplanes
Delegation Option Authorization Organization who has been authorized
by the Manager, Seattle ACO, to make those findings. For a repair
method to be approved, the repair must meet the certification basis
of the airplane, and the approval must specifically refer to this
AD.
Material Incorporated by Reference
(j) You must use Boeing Special Attention Service Bulletin 737-
57-1289, dated June 13, 2007, to do the actions required by this AD,
unless the AD specifies otherwise.
(1) The Director of the Federal Register approved the
incorporation by reference of this service information under 5
U.S.C. 552(a) and 1 CFR part 51.
(2) For service information identified in this AD, contact
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington
98124-2207.
(3) You may review copies of the service information
incorporated by reference at the FAA, Transport Airplane
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the
National Archives and Records Administration (NARA). For information
on the availability of this material at 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 June 10, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E8-14475 Filed 7-7-08; 8:45 am]
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