[Federal Register Volume 76, Number 151 (Friday, August 5, 2011)]
[Proposed Rules]
[Pages 47522-47527]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-19904]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2011-0722; Directorate Identifier 2010-NM-262-AD]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: We propose to supersede an existing airworthiness directive 
(AD) that applies to certain Model 737-100 and -200 series airplanes. 
The existing AD currently requires various inspections for cracks in 
the outboard chord of the frame at body station (BS) 727 and in the 
outboard chord of stringer (S) 18A, and repair or replacement of 
cracked parts. Since we issued that AD, there have been several reports 
of fatigue cracking in the frame outboard chord at BS 727 and in the 
radius of the auxiliary chord on airplanes that were not affected by 
the existing AD. This proposed AD would add airplanes to the 
applicability statement in the existing AD and add inspections for 
cracks in the BS 727 frame outboard chords and the radius of the 
auxiliary chord, for certain airplanes. This proposed AD would also 
remove the inspections of the outboard chord of S-18A required by the 
existing AD. We are proposing this AD to detect and correct fatigue 
cracking of the outboard and auxiliary chords, which

[[Page 47523]]

could result in reduced structural integrity of the outboard chord and 
consequent rapid decompression of the airplane.

DATES: We must receive comments on this proposed AD by September 19, 
2011.

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: Deliver to Mail address above 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, Attention: Data & Services Management, P.O. Box 
3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-544-5000, 
extension 1; fax 206-766-5680; e-mail [email protected]; Internet 
https://www.myboeingfleet.com. You may review copies of the referenced 
service information at the FAA, Transport Airplane Directorate, 1601 
Lind Avenue, SW., Renton, Washington. For information on the 
availability of this material at the FAA, call 425-227-1221.

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 (phone: 800-647-5527) is in the ADDRESSES 
section. Comments will be available in the AD docket shortly after 
receipt.

FOR FURTHER INFORMATION CONTACT: Alan Pohl, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; phone (425) 917-
6450; fax (425) 917-6590; e-mail [email protected].

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-2011-0722; 
Directorate Identifier 2010-NM-262-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 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

    On June 5, 1995, we issued AD 95-12-17, amendment 39-9268 (60 FR 
36981, July 19, 1995), for certain Model 737-100 and -200 series 
airplanes. That AD requires various inspections for cracks in the 
outboard chord of the frame at body station (BS) 727 and in the 
outboard chord of stringer (S) 18A, and repair or replacement of 
cracked parts. That AD resulted from reports of fatigue cracks in those 
outboard chords. We issued that AD to prevent such fatigue cracking, 
which could result in reduced structural integrity of the outboard 
chords, and subsequent rapid decompression of the airplane.

Actions Since Existing AD Was Issued

    Since we issued AD 95-12-17, we have received several reports of 
fatigue cracking in the frame outboard chord at BS 727 and in the 
radius of the auxiliary chord. The cracking in the chords occurred on 
airplanes that had accumulated between 20,000 and 52,000 total flight 
cycles, and between 27,000 and 74,000 total flight hours. The cracking 
in the auxiliary chord occurred on airplanes that had accumulated 
between 46,000 and 85,000 total flight cycles, and between 41,000 and 
64,000 total flight hours. This cracking is caused by fatigue. The 
airplanes that are affected by AD 95-12-17 were produced with outboard 
chords at BS 727 made of 7075-T6 aluminum; subsequent airplanes were 
produced with outboard chords made of 7075-T73 aluminum.
    In addition, we have determined that the inspections of the 
outboard chord of S-18A required by the existing AD are no longer 
necessary. The new inspections (described below) will decrease the 
probability of cracks in the frame at BS 727 where S-18A is attached.

Relevant Service Information

    We reviewed Boeing Alert Service Bulletin 737-53A1166, Revision 2, 
dated May 25, 2006. The existing AD refers to Boeing Alert Service 
Bulletin 737-53A1166, dated June 30, 1994; and Boeing Service Bulletin 
737-53A1166, Revision 1, dated May 25, 1995; for accomplishing the 
required actions. Revision 1 of this service bulletin was issued to 
include airplanes having 7075-T73 frame outboard chords. Revision 2 of 
this service bulletin expands the effectivity in Revision 1 of this 
service bulletin, and adds inspections for cracks of the 7075-T73 frame 
outboard chord and in the radius of the auxiliary chord, and repair or 
replacement if necessary.

FAA's Determination

    We are proposing this AD because we evaluated all the relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design.

Proposed AD Requirements

    This proposed AD would retain certain requirements of AD 95-12-17. 
This proposed AD would add airplanes to the applicability statement in 
the existing AD. This proposed AD would also remove the inspections of 
the outboard chord of S-18A required by the existing AD, and add 
inspections for cracks in the BS 727 frame outboard chords and the 
radius of the auxiliary chord, for certain airplanes. This proposed AD 
would require accomplishing the actions specified in the service 
information described previously, except as discussed under 
``Difference Between the Proposed AD and the Service Information.''

Change to Existing AD

    Since AD 95-12-17 was issued, the AD format has been revised, and 
certain paragraphs have been rearranged. As a result, the corresponding 
paragraph identifiers have changed in this proposed AD, as listed in 
the following table:

                      Revised Paragraph Identifiers
------------------------------------------------------------------------
                                                         Corresponding
             Requirement in AD 95-12-17                 requirement in
                                                       this  proposed AD
------------------------------------------------------------------------
paragraph (a).......................................      paragraph (g)
paragraph (b).......................................      paragraph (h)
paragraph (c).......................................      paragraph (i)
paragraph (d).......................................      paragraph (j)
paragraph (e).......................................            removed
paragraph (f).......................................      paragraph (k)
paragraph (g).......................................      paragraph (l)
------------------------------------------------------------------------


[[Page 47524]]

Difference Between the Proposed AD and the Service Information

    Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 
25, 2006, specifies contacting the manufacturer for instructions on how 
to repair a certain condition, but this AD requires repairing that 
condition 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 Organization Designation 
Authorization whom we have authorized to make those findings.

Costs of Compliance

    We estimate that this proposed AD affects 574 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                    Cost per       Cost on U.S.   Number of U.S.
            Action                Labor cost      Parts cost        product         operators        airplanes
----------------------------------------------------------------------------------------------------------------
Various inspections (retained  4 work-hours x               $0  $340 per         $100,640 per                296
 actions from existing AD).     $85 per hour =                   inspection       inspection
                                $340 per                         cycle.           cycle.
                                inspection
                                cycle.
Ultrasonic inspection (new     13 work-hours x               0  1,105 per        634,270 per                 574
 proposed action).              $85 per hour =                   inspection       inspection
                                $1,105 per                       cycle.           cycle.
                                inspection
                                cycle.
Detailed and HFEC inspections  13 work-hours x               0  1,105 per        634,270 per                 574
 (new proposed actions).        $85 per hour =                   inspection       inspection
                                $1,105 per                       cycle.           cycle.
                                inspection
                                cycle.
----------------------------------------------------------------------------------------------------------------

    We estimate the following costs to do any necessary repairs that 
would be required based on the results of the proposed inspections. We 
have no way of determining the number of aircraft that might need these 
repairs:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Optional modification (retained action from     50 work-hours x $85 per hour =            $3,680          $7,930
 existing AD).                                   $4,250.
Repair of cracking of the outboard chord frame  514 work-hours x $85 per hour =           13,586          57,276
                                                 $42,690.
Time-limited repair cracking of the outboard    63 work-hours x $85 per hour =             2,732           8,087
 chord frame.                                    $5,355.
Repair of cracking of the outboard chord......  49 work-hours x $85 per hour =             4,255           8,420
                                                 $4,165.
----------------------------------------------------------------------------------------------------------------

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),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) 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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, 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 FAA amends Sec.  39.13 by removing airworthiness directive 
(AD) 95-12-17, Amendment 39-9268 (60 FR 36981, July 19, 1995), and 
adding the following new AD:

The Boeing Company: Docket No. FAA-2011-0722; Directorate Identifier 
2010-NM-262-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by September 
19, 2011.

[[Page 47525]]

Affected ADs

    (b) This AD supersedes AD 95-12-17, Amendment 39-9268.

Applicability

    (c) This AD applies to all The Boeing Company Model 737-100, -
200, -200C, -300, -400, and -500 series airplanes, certificated in 
any category.

Subject

    (d) Joint Aircraft System Component (JASC)/Air Transport 
Association (ATA) of America Code 53, Fuselage.

Unsafe Condition

    (e) This AD was prompted by several reports of fatigue cracking 
in the frame outboard chord at body station (BS) 727, and cracks in 
the radius of the auxiliary chord on airplanes that were not 
affected by the existing AD. We are issuing this AD to detect and 
correct fatigue cracking of the outboard and auxiliary chords, which 
could result in reduced structural integrity of the outboard chord 
and consequent rapid decompression of the airplane.

Compliance

    (f) Comply with this AD within the compliance times specified, 
unless already done.

Restatement of Certain Requirements of AD 95-12-17 With Revised Service 
Information: Repetitive Inspections and Repair or Replacement

    (g) For Model 737-100 and -200 series airplanes on which the BS 
727 frame upper outboard chord has been replaced in accordance with 
Boeing Service Bulletin 737-53-1088: Prior to the accumulation of 
30,000 total flight cycles since replacement of the upper outboard 
chord, or within 4,500 flight cycles after August 18, 1995 (the 
effective date of AD 95-12-17), whichever occurs later, perform 
close visual, pulse echo shear wave (PESW), and high frequency eddy 
current (HFEC) inspections to detect cracks in the outboard chord of 
the frame at BS 727, in accordance with Part I of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1166, dated 
June 30, 1994; Boeing Service Bulletin 737-53A1166, Revision 1, 
dated May 25, 1995; or Boeing Alert Service Bulletin 737-53A1166, 
Revision 2, dated May 25, 2006; as applicable. As of the effective 
date of this AD use only Revision 2 of this service bulletin.
    (h) For Model 737-100 and -200 series airplanes on which the BS 
727 frame upper outboard chord has been replaced in accordance with 
Boeing Service Bulletin 737-53-1088: Repeat the inspections required 
by paragraph (g) of this AD at the time specified in paragraphs 
(h)(1), (h)(2), (h)(3), and (h)(4) of this AD, as applicable, until 
the optional terminating action described in paragraph (l) of this 
AD is accomplished.
    (1) If, at the time of the most recent inspection required by 
paragraph (g) or (h) of this AD, the airplane has accumulated 27,000 
or more total flight cycles, but fewer than 50,000 total flight 
cycles since the replacement of the outboard chord: Perform the next 
inspection within 15,000 flight cycles. Repeat the inspection 
thereafter at intervals not to exceed 15,000 flight cycles until the 
airplane has accumulated 50,000 or more total flight cycles since 
the replacement of the outboard chord. Do the inspections required 
by paragraph (h)(2) of this AD at the time specified.
    (2) If, at the time of the most recent inspection required by 
paragraph (g) or (h) of this AD, the airplane has accumulated 50,000 
or more total flight cycles, but fewer than 60,000 total flight 
cycles, since the replacement of the outboard chord: Perform the 
next inspection within 7,500 flight cycles. Repeat the inspection 
thereafter at intervals not to exceed 7,500 flight cycles until the 
airplane has accumulated 60,000 or more total flight cycles since 
the replacement of the outboard chord. Do the inspections required 
by paragraph (h)(3) of this AD at the time specified.
    (3) If, at the time of the most recent inspection required by 
paragraph (g) or (h) of this AD, the airplane has accumulated 60,000 
or more total flight cycles, but fewer than 70,000 total flight 
cycles, since the replacement of the outboard chord: Perform the 
next inspection within 5,000 flight cycles. Repeat the inspection 
thereafter at intervals not to exceed 5,000 flight cycles until the 
airplane has accumulated 70,000 or more total flight cycles since 
the replacement of the outboard chord. Do the inspections required 
by paragraph (h)(4) of this AD at the time specified.
    (4) If, at the time of the most recent inspection required by 
paragraph (g) or (h) of this AD, the airplane has accumulated 70,000 
or more total flight cycles since replacement of the outboard chord: 
Perform the next inspection within 3,000 flight cycles. Repeat the 
inspection thereafter at intervals not to exceed 3,000 flight 
cycles.
    (i) For Model 737-100 and -200 series airplanes on which the BS 
727 frame outboard chord has not been replaced, or on which only the 
lower outboard chord has been replaced in accordance with Boeing 
Service Bulletin 737-53-1088: Perform close visual, PESW, and HFEC 
inspections to detect cracks in the outboard chord of the frame at 
BS 727, in accordance with Part I of the Accomplishment Instructions 
of Boeing Alert Service Bulletin 737-53A1166, dated June 30, 1994; 
Boeing Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; 
or Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 
25, 2006; as applicable. As of the effective date of this AD, use 
only Revision 2 of this service bulletin. Perform these inspections 
initially at the time specified in paragraph (i)(1), (i)(2), (i)(3), 
or (i)(4), as applicable. Repeat these inspections thereafter at the 
intervals specified in paragraph (j) of this AD.
    (1) For airplanes that have accumulated 27,000 or more total 
flight cycles, but fewer than 50,000 total flight cycles, as of 
August 18, 1995: Inspect prior within 4,500 flight cycles after 
August 18, 1995.
    (2) For airplanes that have accumulated 50,000 or more total 
flight cycles, but fewer than 60,000 total flight cycles, as of 
August 18, 1995: Inspect prior to the accumulation of 2,500 flight 
cycles after August 18, 1995.
    (3) For airplanes that have accumulated 60,000 or more total 
flight cycles, but fewer than 70,000 total flight cycles as of 
August 18, 1995: Inspect prior to the accumulation of 1,500 flight 
cycles after August 18, 1995.
    (4) For airplanes that have accumulated 70,000 or more total 
flight cycles as of August 18, 1995: Inspect prior to the 
accumulation of 500 flight cycles or within 90 days after August 18, 
1995, whichever occurs first.
    (j) Repeat the inspections required by paragraph (i) of this AD 
at the time specified in paragraphs (j)(1), (j)(2), (j)(3), and 
(j)(4) of this AD, as applicable, until the optional terminating 
action described in paragraph (l) of this AD is accomplished:
    (1) If, at the time of the most recent inspection required by 
paragraph (i) or (j) of this AD, the airplane has accumulated 27,000 
or more total flight cycles, but fewer than 50,000 total flight 
cycles: Perform the next inspection within 15,000 flight cycles. 
Repeat the inspection thereafter at intervals not to exceed 15,000 
flight cycles until the airplane has accumulated 50,000 or more 
total flight cycles. Do the inspections required by paragraph (j)(2) 
of this AD at the time specified.
    (2) If, at the time of the most recent inspection required by 
paragraph (i) or (j) of this AD, the airplane had accumulated 50,000 
or more total flight cycles, but fewer than 60,000 total flight 
cycles: Perform the next inspection within 7,500 flight cycles. 
Repeat the inspection thereafter at intervals not to exceed 7,500 
flight cycles until the airplane has accumulated 60,000 or more 
total flight cycles. Do the inspections required by paragraph (j)(3) 
of this AD at the time specified.
    (3) If, at the time of the most recent inspection required by 
paragraph (i) or (j) of this AD, the airplane had accumulated 60,000 
or more total flight cycles, but fewer than 70,000 total flight 
cycles: Perform the next inspection within 5,000 flight cycles. 
Repeat the inspection thereafter at intervals not to exceed 5,000 
flight cycles until the airplane has accumulated 70,000 or more 
total flight cycles. Do the inspections required by paragraph (j)(4) 
of this AD at the time specified.
    (4) If, at the time of the most recent inspection required by 
paragraph (i) or (j) of this AD, the airplane had accumulated 70,000 
or more total flight cycles: Perform the next inspection within 
3,000 flight cycles. Repeat the inspection thereafter at intervals 
not to exceed 3,000 flight cycles.
    (k) If any crack is found in the outboard chord of the frame at 
BS 727 during any inspection required by paragraphs (g) through (j) 
of this AD, accomplish paragraph (k)(1) or (k)(2) of this AD, as 
applicable, in accordance with Boeing Alert Service Bulletin 737-
53A1166, dated June 30, 1994; Boeing Service Bulletin 737-53A1166, 
Revision 1, dated May 25, 1995; or Boeing Alert Service Bulletin 
737-53A1166, Revision 2, dated May 25, 2006; as applicable. As of 
the effective date of this AD, use only Revision 2 of this service 
bulletin.
    (1) For any crack that extends from the forward edge of the 
chord or from the forward fastener hole, but that does not

[[Page 47526]]

extend past the second fastener hole, accomplish either paragraph 
(l)(1)(i) or (l)(1)(ii) of this AD. Thereafter, perform initial and 
repetitive inspections in accordance with paragraphs (g) and (h) of 
this AD.
    (i) Prior to further flight, install the time limited repair. 
Within 4,500 flight cycles or within 18 months after accomplishing 
the time-limited repair, whichever occurs first, replace the 
outboard chord. Or
    (ii) Prior to further flight, replace the outboard chord.

    Note 1:  Boeing Alert Service Bulletin 737-53A1166, dated June 
30, 1994; Boeing Service Bulletin 737-53A1166, Revision 1, dated May 
25, 1995; and Boeing Alert Service Bulletin 737-53A1166, Revision 2, 
dated May 25, 2006; refer to Boeing Service Bulletin 737-53-1088 as 
an additional source of guidance for procedures to replace the 
chord.

    (2) For any crack that extends from the forward edge of the 
chord, or from the forward fastener hole, and that extends past the 
second fastener hole, prior to further flight, replace the outboard 
chord in accordance with Boeing Alert Service Bulletin 737-53A1166, 
dated June 30, 1994; Boeing Service Bulletin 737-53A1166, Revision 
1, dated May 25, 1995; or Boeing Alert Service Bulletin 737-53A1166, 
Revision 2, dated May 25, 2006; as applicable. As of the effective 
date of this AD, use only Revision 2 of this service bulletin. 
Thereafter, perform initial and repetitive inspections in accordance 
with paragraphs (g) and (h) of this AD.

New Requirements of This AD: Repetitive Inspections/Repair or Replace 
if Necessary

    (l) For airplanes identified in table 5 of paragraph 1.E., 
``Compliance'' of Boeing Alert Service Bulletin 737-53A1166, 
Revision 2, dated May 25, 2006: Before the accumulation of 27,000 
total flight cycles, or within 5,000 flight cycles after the 
effective date of this AD, whichever occurs later, do internal 
detailed and HFEC inspections to detect cracks in the auxiliary 
chord radius of the frame at BS 727, in accordance with Part 1 of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-53A1166, Revision 2, dated May 25, 2006. Repeat the inspections 
thereafter at intervals not to exceed 15,000 flight cycles until the 
optional terminating action described in paragraph (r) of this AD is 
accomplished. If any crack is found, before further flight, repair 
in accordance with the requirements in paragraph (p) of this AD.
    (m) For airplanes identified in table 2 of paragraph 1.E., 
``Compliance'' of Boeing Alert Service Bulletin 737-53A1166, 
Revision 2, dated May 25, 2006: Do the applicable inspections 
required by paragraph (m)(1) or (m)(2) of this AD at the time 
specified, in accordance with Part 1 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 
2, dated May 25, 2006. Except as required by paragraph (p) of this 
AD, if any crack is found during any inspection required by 
paragraph (m)(1) or (m)(2) of this AD, before further flight, repair 
in accordance with Part 3 or Part 4 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 
2, dated May 25, 2006, as applicable. Repeat the inspections until 
the optional terminating action described in paragraph (r) of this 
AD is accomplished.
    (1) For airplanes on which the inspections specified in Boeing 
Alert Service Bulletin 737-53A1166, dated June 30, 1994; or Boeing 
Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; have 
not been performed as of the effective date of this AD: Do the 
inspections required by paragraphs (m)(1)(i) and (m)(1)(ii) of this 
AD at the time specified.
    (i) Before the accumulation of 27,000 total flight cycles, or 
within 5,000 flight cycles after the effective date of this AD, 
whichever occurs later: Do ultrasonic and surface HFEC inspections 
to detect cracks in the forward flange of the outboard chord of the 
frame at BS 727. Repeat the inspections thereafter at intervals not 
to exceed 5,000 flight cycles.
    (ii) Before the accumulation of 27,000 total flight cycles, or 
within 10,000 flight cycles after the effective date of this AD, 
whichever occurs later: Do an open hole eddy current inspection to 
detect cracks in the forward flange of the outboard chord of the 
frame at BS 727. Repeat the inspection thereafter at intervals not 
to exceed 15,000 flight cycles.
    (2) For airplanes on which the inspections specified in Boeing 
Alert Service Bulletin 737-53A1166, dated June 30, 1994; or Boeing 
Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; have 
been performed as of the effective date of this AD: Repeat the 
applicable inspection specified in paragraphs (m)(1)(i) and 
(m)(1)(ii) of this AD thereafter at intervals not to exceed 5,000 
flight cycles for the ultrasonic and surface HFEC inspections, and 
at intervals not to exceed 15,000 flight cycles for the open hole 
eddy current inspection.
    (n) For airplanes identified in table 3 of paragraph 1.E., 
``Compliance'' of Boeing Alert Service Bulletin 737-53A1166, 
Revision 2, dated May 25, 2006: Do the applicable inspections 
required by paragraph (n)(1) or (n)(2) of this AD at the time 
specified, in accordance with Part 1 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 
2, dated May 25, 2006. Except as required by paragraph (p) of this 
AD, if any crack is found during any inspection required by 
paragraphs (n)(1) or (n)(2) of this AD, before further flight, 
repair in accordance with Part 3 or Part 4 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1166, Revision 
2, dated May 25, 2006, as applicable. Repeat the inspections until 
the optional terminating action described in paragraph (r) of this 
AD is accomplished.
    (1) For airplanes on which the inspections specified in Boeing 
Alert Service Bulletin 737-53A1166, dated June 30, 1994; or Boeing 
Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; have 
not been done as of the effective date of this AD: Do the 
inspections required by paragraphs (n)(1)(i) and (n)(1)(ii) of this 
AD at the time specified.
    (i) Before the accumulation of 27,000 total flight cycles, or 
within 5,000 flight cycles after the effective date of this AD, 
whichever occurs later: Do ultrasonic, low frequency eddy current, 
and edge HFEC inspections to detect cracks in the forward flange of 
the outboard chord of the frame at BS 727. Repeat the inspections 
thereafter at intervals not to exceed 5,000 flight cycles.
    (ii) Before the accumulation of 27,000 total flight cycles, or 
within 10,000 flight cycles after the effective date of this AD, 
whichever occurs later: Do an open hole eddy current inspection to 
detect cracks in the forward flange of the outboard chord of the 
frame at BS 727. Repeat the inspections thereafter at intervals not 
to exceed 15,000 flight cycles.
    (2) For airplanes on which the inspections specified in Boeing 
Alert Service Bulletin 737-53A1166, dated June 30, 1994; or Boeing 
Service Bulletin 737-53A1166, Revision 1, dated May 25, 1995; have 
been done as of the effective date of this AD: Repeat the applicable 
inspection specified in paragraphs (n)(1)(i) and (n)(1)(ii) of this 
AD thereafter at intervals not to exceed 5,000 flight cycles for the 
ultrasonic, low frequency eddy current, and edge HFEC inspections, 
and at intervals not to exceed 15,000 flight cycles for the open 
hole eddy current inspection.

    Note 2: The detailed and eddy current inspections of the 
outboard chord of S-18A specified in Boeing Alert Service Bulletin 
737-53A1166, Revision 2, dated May 25, 2006, are not required by 
this AD.

    (o) For airplanes identified in table 4 of paragraph 1.E., 
``Compliance'' of Boeing Alert Service Bulletin 737-53A1166, 
Revision 2, dated May 25, 2006: Before the accumulation of 50,000 or 
more total flight cycles, but fewer than or equal to 60,000 total 
flight cycles, after accomplishing the modification of the outboard 
chord of the frame at BS 727 at S-18A: Do a one-time follow-on open 
hole eddy current inspection to detect cracks in the modified chord 
in accordance with Part 8 of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated May 25, 
2006.
    (p) If any crack is found during any inspection required by 
paragraphs (l) through (o) of this AD, and the repairs specified in 
Part 3 and Part 4 of the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1166, Revision 2, dated May 25, 2006, can 
not be installed using the procedures identified in this service 
bulletin: Before further flight, repair using a method approved in 
accordance with the procedures specified in paragraph (s) of this 
AD.
    (q) For any airplane on which a time-limited repair is installed 
on the outboard chord of the frame at body station BS 727 in 
accordance with Boeing Alert Service Bulletin 737-53A1166, dated 
June 30, 1994; or Boeing Service Bulletin 737-53A1166, Revision 1, 
dated May 25, 1995: Within 4,500 flight cycles after installation of 
the repair, or within 6 months after the effective date of this AD, 
whichever occurs later, replace the repair in accordance with Part 9 
of the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-53A1166, Revision 2, dated May 25, 2006.

Optional Terminating Action

    (r) Accomplishment of the applicable action specified in 
paragraph (r)(1) or (r)(2) of this AD, in accordance with Part 2 of 
the Accomplishment Instructions of Boeing Alert

[[Page 47527]]

Service Bulletin 737-53A1166, dated June 30, 1994; Boeing Service 
Bulletin 737-53A1166, Revision 1, dated May 25, 1995; or Part 6 of 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-53A1166, Revision 2, dated May 25, 2006; constitutes terminating 
action for the inspections required by this AD.
    (1) Installation of the preventative modification.
    (2) Replacement of the cracked chord and installation of the 
preventative modification.

Alternative Methods of Compliance (AMOCs)

    (s)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested 
using the procedures found in 14 CFR 39.19. In accordance with 14 
CFR 39.19, send your request to your principal inspector or local 
Flight Standards District Office, as appropriate. If sending 
information directly to the manager of the ACO, send it to the 
attention of the person identified in the Related Information 
section of this AD. Information may be e-mailed to: [email protected].
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.
    (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 the 
Boeing Commercial Airplanes Organization Designation Authorization 
(ODA) that 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.
    (4) AMOCs approved for AD 95-12-17 are approved as AMOCs for the 
corresponding provisions of this AD.
    (5) For airplanes identified in tables 2, 3, and 5 of paragraph 
1.E., ``Compliance'' of Boeing Alert Service Bulletin 737-53A1166, 
Revision 2, dated May 25, 2006: The Manager, Seattle ACO, approves 
the inspection methods, thresholds, and repetitive intervals therein 
as an AMOC for the inspections of Structurally Significant Items 
(SSIs) F-29A and F-29B required by paragraphs (g) and (h) of AD 
2008-08-23, Amendment 39-15477 (Boeing 737-100/200/200C Supplemental 
Structural Inspection Document (SSID) D6-37089, Revision E, dated 
May 1, 2007), and paragraphs (g) and (h) of AD 2008-09-13, Amendment 
39-15494 (Boeing 737-400/500/600 SSID D6-82669, dated May 1, 2007). 
This approval applies only to SSIs F-29A and F-29B of the applicable 
SSID and only for the portions of the BS 727 outer chord that have 
been inspected or that have been repaired or modified in accordance 
with Boeing Alert Service Bulletin 737-53A1166, Revision 2, dated 
May 25, 2006. All provisions of ADs 2008-08-23 and 2008-09-13 that 
are not specifically referenced in this paragraph remain fully 
applicable and must be done. If operators request this AMOC, they 
must revise their FAA-approved maintenance or inspection program to 
incorporate the alternative inspections in this paragraph.

Related Information

    (t) For more information about this AD, contact Alan Pohl, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; phone: (425) 
917-6450; fax: (425) 917-6590; e-mail: [email protected].
    (u) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 
206-544-5000, extension 1; fax 206-766-5680; e-mail 
[email protected]; Internet https://www.myboeingfleet.com. You 
may review copies of the referenced service information at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington. For information on the availability of this material at 
the FAA, call 425-227-1221.

    Issued in Renton, Washington, on July 26, 2011.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-19904 Filed 8-4-11; 8:45 am]
BILLING CODE 4910-13-P