[Federal Register: October 24, 2007 (Volume 72, Number 205)]
[Rules and Regulations]
[Page 60244-60247]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr24oc07-8]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2007-27560; Directorate Identifier 2006-NM-211-AD;
Amendment 39-15198; AD 2007-19-07]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 757-200, -200PF, and -
200CB 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 757-200, -200PF, and -200CB series airplanes. This
AD requires inspections to detect scribe lines and cracks of the
fuselage skin, lap joints, circumferential butt splice strap, and
external and internal approved repairs; and related investigative/
corrective actions if necessary. This AD results from reports of scribe
lines adjacent to the skin lap joints. We are issuing this AD to detect
and correct cracks, which could grow and cause rapid decompression of
the airplane.
DATES: This AD becomes effective November 28, 2007.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in the AD as of November 28,
2007.
ADDRESSES: You may examine the AD docket on the Internet at http://dms.dot.gov
or in person at the U.S. Department of Transportation,
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200
New Jersey Avenue, SE., 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: Dennis Stremick, Aerospace Engineer,
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office,
1601 Lind Avenue SW., Renton, Washington 98057-3356; telephone (425)
917-6450; fax (425) 917-6590.
SUPPLEMENTARY INFORMATION:
Examining the Docket
You may examine the AD docket on the Internet at http://dms.dot.gov
or in person at the Docket Operations office between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays. The Docket Operations
office (telephone (800) 647-5527) is located on the ground floor of the
West Building at the DOT 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
757-200, -200PF, and -200CB series airplanes. That NPRM was published
in the Federal Register on March 15, 2007 (72 FR 12125). That NPRM
proposed to require inspections to detect scribe lines and cracks of
the fuselage skin, lap joints, circumferential butt splice strap, and
external and internal approved repairs; and related investigative/
corrective actions if necessary.
Comments
We provided the public the opportunity to participate in the
development of this AD. We have considered the comments received.
Support for the NPRM
Boeing, Continental Airlines (CAL), and the National Transportation
Safety Board (NTSB) support the NPRM.
Request To Extend Rulemaking to Additional Airplanes
The NTSB asserts that scribe lines could be present on virtually
every pressurized airplane in service. The NTSB requests that we
examine and expedite similar rulemaking for other makes and models of
airplanes in addition to the Model 757 airplanes subject to the NPRM.
We acknowledge the NTSB's concerns. The unsafe condition identified
in this action is a long-term durability issue that might not be
limited to any particular airplane model. The potential consequences
for each airplane model will vary with each model's design
characteristics and operating conditions. To this end, we have
coordinated efforts with other governing regulatory agencies and other
manufacturers to investigate the existence of scribe lines on other
airplanes and any potential safety risks associated with such scribe
lines. As a result of these efforts, we might consider similar
rulemaking on other airplanes.
Pending the inspection results provided in the reports required by
this AD, we might consider further rulemaking to require inspections on
Model 757-300 airplanes. And we are considering similar rulemaking for
Boeing Model 747 airplanes. We have already issued an AD for all Boeing
Model 737-100, -200, -200C, -300, -400, and -500 series airplanes (AD
2006-07-12, amendment 39-14539, 71 FR 16211, March 31, 2006).
Request To Revise Compliance Time
Continental Airlines (CAL) believes that the accomplishment
timetables in Boeing Service Bulletin 757-53A0092, Revision 1, dated
January 10, 2007, for approved repairs are overly conservative. CAL
notes that scribe lines on flush repairs are not considered critical on
Model 737 airplanes, and AD 2006-07-12 does not require similar
inspections for those airplanes. CAL compares compliance times for
initial scribe line inspections with those for approved repair
inspections, and asserts that the proposed repair inspection would
occur in a line environment without benefit of the support offered
during a heavy maintenance check. CAL notes that no crack attributable
to scribe lines has ever been found on the Model 757 fleet and that the
Model 757 scribe line program is extrapolated from the Model 737
program; in the Model 737 scribe line inspection program all approved
repair inspections generally coincide in accomplishment timeframe with
the main scribe line program. Therefore CAL requests that we revise the
accomplishment timetables of the approved repair section of the 757
scribe line program to better coincide with the mainline program.
We disagree with the request. The timetables, developed by Boeing
in cooperation with the 757 Scribe Line Working Group, are based on
extensive technical evaluation and analysis to reflect the differences
in construction between the two models. In determining the
appropriateness of the proposed compliance times, we considered the
average utilization rate of the affected fleet, the practical aspects
of an orderly inspection of the fleet during regular maintenance
periods. We have determined that the compliance times, as proposed,
will ensure an acceptable level of safety. We have not changed the
final rule regarding this issue.
Request for Limited Return to Service (LRTS) Program for Zone C
Continental Airlines (CAL) notes that Table 5 (paragraph 1.E.) of
the service bulletin specifies inspections for scribe lines on approved
repairs in Zone C but provides no limited return to service (LRTS)
program if scribe lines are found. CAL notes that these inspections
will be required much earlier than other inspections in the program.
Due to their urgent nature, these inspections will be required to be
done in a line maintenance environment, instead of a longer span heavy
check. CAL concludes that the lack of a readily
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available approved LRTS for any scribe lines found during these
inspections would have a significantly negative impact on its
operation. CAL believes that typical scribe lines found on such repairs
should have an approved LRTS for several reasons. No scribe lines on
approved repairs have resulted in cracks on the Model 757 fleet.
Approved repairs on Model 757 skins would by definition include enough
static strength to contain the damage to the local area, as well as
damage tolerance analysis as mandated by section 25.571 of the Federal
Aviation Regulations (14 CFR 25.571). Even if analysis is not ready for
such repairs, CAL suggests imposing the most conservative inspection
interval of 250 flight cycles, as specified in the Model 737 LRTS
program, so that an airline could continue its operation until a more
permanent disposition can be approved by Boeing and the FAA.
We disagree. Providing repair instructions in the service bulletin
for all possible repair conditions is not feasible. The LRTS program
must be customized for individual repair configurations. For Zone C,
the service bulletin specifies contacting Boeing for additional
analysis and an LRTS program. We have not changed the final rule
regarding this issue.
Request To Revise LRTS Inspection Interval
Because no cracking has been found on Model 757 airplanes, American
Airlines requests that we relax the proposed interval for the LRTS
inspections. First, the commenter requests that we revise the NPRM to
allow operators to inspect at the next scheduled C-check (as an option
to the proposed flight-cycle interval). Second, the commenter requests
that subsequent inspections be done within an applicable flight-cycle
interval, or at the next scheduled C-check after the last LRTS
inspection. Third, the commenter requests that we extend the interval
for an LRTS inspection, which includes the decal inspection area in
Zone C, from 1,000 flight cycles, which the commenter finds overly
frequent, to 1,500 flight cycles, which is in line with the other
intervals for similar inspection areas.
We disagree with the requests. The intervals were developed by
Boeing in conjunction with the Model 757 scribeline working group based
on analysis and technical evaluations to reflect the Model 757's unique
construction details and stresses. We have determined that the proposed
compliance times represent the maximum intervals allowable for affected
airplanes to continue to safely operate before the inspections are
done. Since maintenance schedules vary among operators, there would be
no assurance that the airplane would be inspected during the maximum
interval if we were to allow operators the option of inspecting at the
next C-check. We have not changed the final rule regarding this issue.
Request for Repair Instructions
Air Transport Association (ATA), on behalf of its member American
Airlines, requests that repair instructions be included in the service
bulletin because requiring FAA approval of each specific repair adds
undue complexity and delay to the process.
We disagree. Each repair will likely be unique and tailored for
specific conditions. It would be impossible to identify repairs that
would adequately address all possible findings in all possible
locations. We have not changed the final rule regarding this issue.
Request To Clarify Compliance Times
ATA, on behalf of American Airlines, considers the compliance time
information specified in the NPRM vague and requests that we revise the
NPRM to simply state that the compliance times specified in the service
bulletin will be mandated by the AD.
We disagree with the need to clarify the compliance times in the
NPRM. Paragraph 1.E. is the standard location of compliance time
information in a service bulletin. The NPRM specified doing the actions
``within the applicable times specified in paragraph 1.E. of the
service bulletin.'' The times specified in the service bulletin are
clear and specific. We have not changed the final rule regarding this
issue.
Request for Alternative Inspection Method: Zones A and B
Northwest Airlines (NWA) requests an alternative inspection method
for the inspections specified in the NPRM for the lap joints and
external repairs in Zones A and B. NWA's proposal would allow operators
to do an ultrasonic phased-array inspection without stripping the paint
from the affected locations, and eventually (before 50,000 total flight
cycles or at the next scheduled fuselage paint removal, whichever
occurs first) stripping the paint from affected locations and
inspecting for scribe lines as specified in the service bulletin. (The
ultrasonic phased-array inspection is described in the Boeing 757 NDT
Manual, Part 4, Section 53-00-02.) NWA believes that its proposal would
eliminate the need to strip the paint, and yet allow the detection of
cracks before they reach an unacceptable length, thereby providing an
acceptable level of safety. NWA adds that these procedures would delay
the unsightly stripping of selected lap splice areas on an airplane
until repainting the entire fuselage was necessary.
We disagree with the request. The fay surface sealant in the lap
joints significantly attenuates the ultrasonic signal, and would affect
the accuracy of the inspection results. This assessment has been
coordinated with Boeing. Further, ultrasonic inspections can detect
only cracks--not scribe lines. We have not changed the final rule
regarding this issue. However, paragraph (j) of the final rule provides
operators the opportunity to request an alternative method of
compliance if the request includes data that prove that the new method
would provide an acceptable level of safety.
Request for Alternative Inspection Method: Parts 9 and 10
Northwest Airlines (NWA) requests that we revise the proposed
requirements for the scribe line inspection and LRTS program (Part 9
and Part 10, respectively, of the service bulletin). Part 9 and Part 10
specify surface high frequency eddy current (HFEC) inspections from the
butt joint forward of the affected scribe line to the butt joint aft of
the affected scribe line, using the Boeing 757 NDT, Part 6, 51-00-01 or
757 NDT, Part 6, 51-00-19 if the scribe line is greater than 0.063 inch
from the lower edge of the upper skin. NWA reports that Boeing has
indicated that the HFEC inspection procedure local to scribe lines
greater than 0.063 inch from the lower edge of the upper skin would be
structurally satisfactory if an ultrasonic inspection specified in the
757 NDT Manual, Part 4, 53-00-01 or 53-00-02 is accomplished from the
butt joint forward of the affected scribe line to the butt joint aft of
the affected scribe line. In addition, NWA understands that an AMOC to
AD 2006-07-12 has been granted for Model 737 airplanes for a similar
inspection technique. This process reduces the area required to be
inspected using pencil probes and will reduce the time required for
inspection. NWA requests that we revise the NPRM to include the
alternative inspection instead of considering this option only through
the AMOC process.
We partially agree with this request. While Model 737 airplanes use
the ultrasonic inspection from the butt joint forward to the butt joint
aft of the affected scribe line, and a HFEC inspection local to scribe
lines greater than 0.063 inch from the lower edge of
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the upper skin, this technique has not yet been confirmed to be
acceptable for use on Model 757 airplanes. We are working with Boeing
to determine if this inspection technique can be used on the Model 757
airplanes. If this technique is acceptable, a fleetwide AMOC might be
issued to allow this technique. We have not changed the final rule
regarding this issue.
Request for Provisions for Converted Airplanes
FedEx reports that it will convert about 90 passenger airplanes
into special freighters. FedEx considers these airplanes, after
conversion, to most closely resemble Group 6 airplanes, as that Group
is defined in the service bulletin. FedEx requests that we revise the
NPRM to do the following: Consider possible prorated compliance times;
identify the appropriate Group for converted airplanes; omit the
inspection area for decals forward of BS 661, where a new panel was
installed during conversion; omit the inspection of the butt joint at
BS 660; and define the areas, compliance times, and damage limits for
the inspection of the upper skins for decals aft of BS 660. According
to FedEx, providing these conditions in the AD instead of an AMOC would
be more expeditious.
We disagree with the request. FedEx provided no details of the
conversion modification, so we cannot evaluate the merits of the claim
that these airplanes are similar to Group 6 airplanes. However, under
the provisions of paragraph (j) of the final rule, we may approve
requests for airplane group reassignments, if details of the
modification are provided that would substantiate that reassigning
these airplanes to Group 6 would be appropriate and provide an
acceptable level of safety. We have not changed the final rule
regarding this issue.
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 as proposed.
Costs of Compliance
There are about 945 airplanes of the affected design in the
worldwide fleet; of these, about 634 are U.S.-registered airplanes. The
following table provides the estimated costs for U.S. operators to
comply with this AD. There are no U.S.-registered airplanes in Group 5
or Group 6.
Estimated Costs
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Number of U.S.-
Inspections Work hours Average labor Cost per registered Fleet cost
rate per hour airplane airplanes
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Group 1...................... 127 $80 $10,160 144 $1,463,040
Group 2...................... 122 80 9,760 6 58,560
Group 3...................... 154 80 12,320 75 924,000
Group 4...................... 128 80 10,240 409 4,188,160
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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):
2007-19-07 Boeing: Amendment 39-15198. Docket No. FAA-2007-27560;
Directorate Identifier 2006-NM-211-AD.
Effective Date
(a) This AD becomes effective November 28, 2007.
Affected ADs
(b) None.
Applicability
(c) This AD applies to Boeing Model 757-200, -200PF, and -200CB
series airplanes, certificated in any category; as identified in
Boeing Service Bulletin 757-53A0092, Revision 1, dated January 10,
2007.
Unsafe Condition
(d) This AD results from reports of scribe lines adjacent to the
fuselage skin lap joints. We are issuing this AD to detect and
correct cracks, which could grow and cause rapid decompression of
the airplane.
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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.
Inspections
(f) Perform detailed inspections to detect scribe lines and
cracks of the fuselage skin, lap joints, circumferential butt splice
strap, and external and internal approved repairs; and perform
related investigative and corrective actions. Do the actions in
accordance with the Accomplishment Instructions of Boeing Service
Bulletin 757-53A0092, Revision 1, dated January 10, 2007, except as
required by paragraph (g) of this AD. Do the actions within the
applicable compliance times specified in paragraph 1.E. of the
service bulletin, except as required by paragraph (h) of this AD.
Exceptions to Service Bulletin Specifications
(g) Where Boeing Service Bulletin 757-53A0092, Revision 1, dated
January 10, 2007, specifies to contact Boeing for appropriate repair
instructions, repair using a method approved in accordance with the
procedures specified in paragraph (j) of this AD.
(h) Boeing Service Bulletin 757-53A0092, Revision 1, dated
January 10, 2007, specifies compliance times relative to the date of
issuance of the service bulletin; however, this AD requires
compliance before the specified compliance time relative to the
effective date of the AD.
Credit for Prior Accomplishment
(i) Inspections done before the effective date of this AD in
accordance with Boeing Alert Service Bulletin 757-53A0092, dated
September 18, 2006, are acceptable for compliance with the
corresponding requirements of paragraph (f) of this AD.
Alternative Methods of Compliance (AMOCs)
(j)(1) The Manager, Seattle Aircraft Certification Office (ACO),
FAA, 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.
Material Incorporated by Reference
(k) You must use Boeing Service Bulletin 757-53A0092, Revision
1, dated January 10, 2007, 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 this
document 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 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/cfr/ibr-locations.html.
Issued in Renton, Washington, on October 15, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E7-20816 Filed 10-23-07; 8:45 am]
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