

[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]                         


[[Page 60244]]

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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

[[Page 60246]]

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]

BILLING CODE 4910-13-P
