[Federal Register Volume 72, Number 218 (Tuesday, November 13, 2007)]
[Proposed Rules]
[Pages 63831-63833]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-22104]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0184; Directorate Identifier 2007-NM-140-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
300, -400, and -500 Series Airplanes

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

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 
series airplanes. This proposed AD would require various repetitive 
inspections for cracking of the upper frame to side frame splice of the 
fuselage, and other specified and corrective actions if necessary. This 
proposed AD also provides for an optional preventive modification, 
which would terminate the repetitive inspections. This proposed AD 
results from a report that the upper frame of the fuselage was severed 
between stringers S-13L and S-14L at station 747, and the adjacent 
frame at station 767 had a 1.3-inch-long crack at the same stringer 
location. We are proposing this AD to detect and correct fatigue 
cracking of the upper frame to side frame splice of the fuselage, which 
could result in reduced structural integrity of the frame and adjacent 
lap joint. This reduced structural integrity can increase loading in 
the fuselage skin, which will accelerate skin crack growth and result 
in decompression of the airplane.

DATES: We must receive comments on this proposed AD by December 28, 
2007.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
    Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    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 proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

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:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2007-0184; 
Directorate Identifier 2007-NM-140-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will

[[Page 63832]]

consider all comments received by the closing date and may amend this 
proposed AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    We have received a report indicating that the upper frame of the 
fuselage was severed between stringers S-13L and S-14L at station 747 
on one airplane that had completed 41,000 total flight cycles, and that 
the adjacent frame at station 767 had a 1.3-inch-long crack at the same 
stringer location. This incident occurred on a Model 737-300 airplane. 
All cracks in the upper frame originated from the upper end fastener 
hole of the frame splice common to the fail safe chord. This condition, 
if not corrected, could result in reduced structural integrity of the 
frame and adjacent lap joint. This reduced structural integrity can 
increase loading in the fuselage skin, which will accelerate skin crack 
growth and result in decompression of the airplane.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 737-53A1261, 
including Appendices A through X inclusive, dated January 19, 2006. The 
service bulletin describes the following procedures for various 
repetitive inspections for cracking of the upper frame to side frame 
splice of the fuselage, and other specified and corrective actions if 
necessary. The inspections and other specified and corrective actions 
are described below:
     Configuration 1 airplanes on which the preventive 
modification specified in Boeing Service Bulletin 737-53-1125 has been 
done: Perform repetitive medium frequency eddy current (MFEC) 
inspections for cracking of the upper frame, repair of any crack before 
further flight, an optional preventive modification, which would 
eliminate the need for the repetitive inspections. The preventive 
modification also involves a high frequency eddy current (HFEC) 
inspection for cracking of the fastener holes in the upper frame and 
side frame, repair of any crack before further flight, and if no crack 
is found, fabricating and installing a modification angle as defined in 
the applicable Appendix.
     Configuration 2 airplanes on which the frame repair 
specified in Boeing Service Bulletin 737-53-1125 has been done: Perform 
a detailed inspection of the frame repair to make sure it follows the 
repair given in the applicable Boeing Model 737 Structural Repair 
Manual (SRM). If the repair is not as given in the SRM, perform any 
applicable corrective actions. Then perform an HFEC inspection for 
cracking of the upper frame. If any crack is found, repair before 
further flight. If no crack is found, repeat the HFEC inspection or 
contact Boeing for applicable terminating action, which would eliminate 
the need for the repetitive inspections.
     Configuration 3 airplanes on which the actions specified 
in Boeing Service Bulletin 737-53-1125 have not been done: Perform an 
MFEC inspection for cracking of the upper frame. The MFEC inspection is 
not necessary if the preventive modification is being accomplished. If 
any crack is found, repair before further flight. If no crack is found, 
repeat the MFEC inspection or do the preventive modification, which 
would eliminate the need for the repetitive inspections. When doing the 
preventive modification, perform an HFEC inspection for cracking of the 
fastener holes in the upper frame and side frame. If any crack is 
found, repair before further flight. If no crack is found, fabricate 
and install a modification angle as defined in the applicable Appendix.
    The service bulletin specifies a compliance time for the initial 
inspection ranging between 30,000 total flight cycles and 50,000 total 
flight cycles, with a grace period of 5,000 flight cycles after the 
release date of the service bulletin, whichever occurs later, depending 
on airplane configuration.
    The corrective actions include repair of any cracks found and 
ensuring that the frame maintains its structural integrity. If, during 
the accomplishment of the corrective actions, the structure that has 
been damaged is not covered in the structural repair manual, the 
service bulletin specifies contacting Boeing for repair. The service 
bulletin also describes procedures for a preventive modification of the 
frame splice joints which would eliminate the need for the repetitive 
inspections. In addition, the service bulletin recommends contacting 
Boeing for certain repair instructions and terminating action for 
certain airplanes.
    Accomplishing the actions specified in the service information is 
intended to adequately address the unsafe condition.

Other Related Service Information

    Boeing Alert Service Bulletin 737-53A1261 refers to Boeing Message 
M-7200-02-01294, dated August 20, 2002, as an additional source of 
service information for accomplishing certain repairs and optional 
terminating action of the preventive modification.
    Boeing Service Bulletin 737-53-1125, dated November 22, 1989, 
Revision 1, dated September 20, 1990, and Revision 2, dated November 
21, 1991, provided a preventive modification to reduce the stress level 
at the first fastener location in the frame splice common to the fail 
safe chord. The preventive modification increased the fatigue life of 
the splice area. However, the service bulletin did not include adequate 
inspections for cracks prior to accomplishing the preventive 
modification; therefore, the inspections specified in Boeing Alert 
Service Bulletin 737-53A1261 (described above) are recommended on 
airplanes on which that preventive modification has been accomplished 
in accordance with Boeing Service Bulletin 737-53-1125.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to exist or develop on other airplanes 
of this same type design. For this reason, we are proposing this AD, 
which would require accomplishing the actions specified in the service 
information described previously, except as discussed under 
``Difference Between the Proposed AD and Alert Service Bulletin.''

Difference Between Proposed AD and Alert Service Bulletin

    The service bulletin specifies to contact the manufacturer for 
instructions on how to repair certain conditions, but this proposed AD 
would require repairing those conditions in one of the following ways:
     Using a method that we approve; or
     Using data that meet the certification basis of the 
airplane, and that have been approved by an Authorized Representative 
for the Boeing Commercial Airplanes Delegation Option Authorization 
Organization whom we have authorized to make those findings.

Costs of Compliance

    There are about 1509 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 524 airplanes of 
U.S. registry. The proposed inspections would take between 18 and 38 
work hours per airplane, depending on airplane configuration, at an 
average labor rate of $80 per work hour. Based on these figures, the 
estimated cost of the

[[Page 63833]]

inspections proposed by this AD for U.S. operators is between $754,560 
and $1,592,960, or $1,440 and $3,040 per airplane, per inspection 
cycle.

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 proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD 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.
    For the reasons discussed above, I certify that the 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. 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 proposed 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, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-0184; Directorate Identifier 2007-NM-
140-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by December 
28, 2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-100, -200, -200C, -300, 
-400, and -500 series airplanes, certificated in any category; as 
identified in Boeing Alert Service Bulletin 737-53A1261, dated 
January 19, 2006.

Unsafe Condition

    (d) This AD results from a report that the upper frame of the 
fuselage was severed between stringers S-13L and S-14L at station 
747, and the adjacent frame at station 767 had a 1.3-inch-long crack 
at the same stringer location. We are issuing this AD to detect and 
correct fatigue cracking of the upper frame to side frame splice of 
the fuselage, which could result in reduced structural integrity of 
the frame and adjacent lap joint. This reduced structural integrity 
can increase loading in the fuselage skin, which will accelerate 
skin crack growth and result in 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.

Repetitive Inspections/Corrective Actions

    (f) At the applicable compliance time listed in paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1261, 
including Appendices A through X inclusive, dated January 19, 2006: 
Do the applicable inspections for cracking of the upper frame to 
side frame splice of the fuselage by doing all of the actions, as 
specified in the Accomplishment Instructions of the service 
bulletin; except as provided by paragraphs (g) and (h) of this AD. 
Do all applicable specified and corrective actions before further 
flight in accordance with the service bulletin. Repeat the 
applicable inspections thereafter at intervals not to exceed 6,000 
flight cycles until the terminating action in paragraph (i) of this 
AD has been accomplished.
    (g) If any crack is found during any inspection required by this 
AD, and the service bulletin specifies to contact Boeing for 
appropriate action: Before further flight, repair the crack in 
accordance with the procedures specified in paragraph (j) of this 
AD.
    (h) If, during the accomplishment of the corrective actions 
required by paragraph (f) of this AD, the structure that has been 
damaged is not covered in the structural repair manual, before 
further flight, repair in accordance with the procedures specified 
in paragraph (j) of this AD.

Optional Terminating Action

    (i) Accomplishing the actions specified in paragraph (i)(1) 
(i)(2) or (i)(3) of this AD, as applicable, terminates the 
repetitive inspections required by paragraph (f) of this AD for the 
repaired or modified frames only.
    (1) Accomplishment of the repair specified in Part 3 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1261, including Appendices A through X inclusive, dated January 
19, 2006, or the preventive modification specified in Part 4 of the 
Accomplishment Instructions of the service bulletin.
    (2) Accomplishment of the repair or the preventive modification 
specified in Boeing Message M-7200-02-01294, dated August 20, 2002.
    (3) Accomplishment of the repair or the preventive modification 
in accordance with a method approved by the Manager, Seattle ACO.

Alternative Methods of Compliance (AMOCs)

    (j)(1) The Manager, Seattle 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.

    Issued in Renton, Washington, on November 5, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E7-22104 Filed 11-9-07; 8:45 am]
BILLING CODE 4910-13-P