Airworthiness Directives; The Boeing Company Airplanes

[Federal Register Volume 80, Number 228 (Friday, November 27, 2015)]
[Rules and Regulations]
[Pages 73949-73955]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-28824]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2014-0346; Directorate Identifier 2014-NM-010-AD; 
Amendment 39-18324; AD 2015-23-08]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
The Boeing Company Model 737-100,-200,-200C,-300,-400, and -500 series 
airplanes. This AD was prompted by reports of cracks in fuselage 
frames, and a report of a missing strap that was not installed on a 
fuselage frame during production. This AD requires an inspection to 
determine if the strap adjacent to a certain stringer is installed, and 
repair if it is missing; repetitive inspections of the frame for 
cracking or a severed frame web; and related investigative and 
corrective actions if necessary. This AD also provides optional actions 
to terminate certain repetitive inspections. We are issuing this AD to 
detect and correct missing fuselage frame straps and frame cracking 
that can result in severed frames which, with multiple adjacent severed 
frames, or the combination of a severed frame and fuselage skin 
chemical mill cracks, can result in uncontrolled decompression of the 
airplane.

DATES: This AD is effective January 4, 2016.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of January 4, 
2016.

ADDRESSES: For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-
5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com. You may view this referenced service information 
at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., 
Renton, WA. For information on the availability of this material at the 
FAA, call 425-227-1221. It is also available on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2014-
0346.''

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2014-
0346; or in person at the Docket Management Facility between 9 a.m. and 
5 p.m., Monday through Friday, except Federal holidays. The AD docket 
contains this AD, the regulatory evaluation, any comments received, and 
other information. The address for the Docket Office (phone: 800-647-
5527) is Docket Management Facility, U.S. Department of Transportation, 
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 
New Jersey Avenue SE., Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Galib Abumeri, Aerospace Engineer, 
Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification 
Office, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-
627-5324; fax: 562-627-5210; email: [email protected].

SUPPLEMENTARY INFORMATION: 

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 by adding an AD that would apply to certain The Boeing Company 
Model 737-100,-200,-200C-300,-400, and-500 series airplanes. The NPRM 
published in the Federal Register on June 30, 2014 (79 FR 36672). The 
NPRM was prompted by reports of cracks in fuselage frames, and a report 
of a missing strap that was not installed on a fuselage frame during 
production. The NPRM proposed to require an inspection to determine if 
the strap adjacent to a certain stringer is installed, and repair if it 
is missing; repetitive inspections of the frame for cracking or a 
severed frame web; and related investigative and corrective actions if 
necessary. The NPRM also provided optional actions to terminate certain 
repetitive inspections. We are issuing this AD to detect and correct 
missing fuselage frame straps and frame cracking that can result in 
severed frames. Continued operation of the airplane with multiple 
adjacent severed frames, or the combination of a severed frame and 
fuselage skin chemical mill cracks, can result in uncontrolled 
decompression of the airplane.

Comments

    We gave the public the opportunity to participate in developing 
this AD. The following presents the comments received on the NPRM (79 
FR 36672,

[[Page 73950]]

June 30, 2014) and the FAA's response to each comment.

Effect of Winglets on AD

    Aviation Partners Boeing stated that installation of winglets per 
Supplemental Type Certificate (STC) ST01219SE (http://rgl.faa.gov/
Regulatory_and_Guidance_Library/rgstc.nsf/0/
ebd1cec7b301293e86257cb30045557a/$FILE/ST01219SE.pdf) does not affect 
the actions specified in the NPRM (79 FR 36672, June 30, 2014.
    We concur with the commenter. We have redesignated paragraph (c) of 
the proposed AD (79 FR 36672, June 30, 2014) as paragraph (c)(1) of 
this AD, and have added a new paragraph (c)(2) to this AD to state that 
installation of STC ST01219SE (http://rgl.faa.gov/
Regulatory_and_Guidance_Library/rgstc.nsf/0/
ebd1cec7b301293e86257cb30045557a/$FILE/ST01219SE.pdf) does not affect 
the ability to accomplish the actions required by this AD. Therefore, 
for airplanes on which STC ST01219SE is installed, a ``change in 
product'' alternative method of compliance (AMOC) approval request is 
not necessary to comply with the requirements of 14 CFR 39.17.

Request To Revise Preamble Wording

    Boeing noted that the SUMMARY of the NPRM (79 FR 36672, June 30, 
2014) explained that some optional actions would terminate ``certain'' 
repetitive inspections. Boeing requested that we use this same wording 
in the Proposed AD Requirements section of the NPRM (which omitted the 
word ``certain'').
    Although we agree with the commenter's statement, the Proposed AD 
Requirements section is not repeated in a final rule. Since the 
referenced omission does not affect the required actions or the unsafe 
condition, no changes to this final rule are needed.

Request To Specify Inspection Method

    Boeing requested that we add an inspection in paragraph (g) of the 
proposed AD (79 FR 36672, June 30, 2014). Boeing stated that this is 
consistent with the compliance information described in Boeing Alert 
Service Bulletin 737-53A1323, dated December 6, 2013.
    We agree with the commenter's request. We inadvertently omitted the 
inspection requirement in paragraph (g) of the proposed AD (79 FR 
36672, June 30, 2014), which is described in Boeing Alert Service 
Bulletin 737-53A1323, dated December 6, 2013. We have revised paragraph 
(g) of this AD to require that the inspection and applicable repair be 
done by using a method approved in accordance with the procedures 
specified in paragraph (q) of this AD. Paragraph (g) of this AD applies 
only to airplanes identified as Group 1 in Boeing Alert Service 
Bulletin 737-53A1323, dated December 6, 2013. Currently, there are no 
Group 1 airplanes in service in the United States, so notice of this 
new requirement is not necessary.

Request To Revise Terminating Action Wording

    Boeing requested that we revise the wording in paragraphs (i) and 
(j) of the proposed AD (79 FR 36672, June 30, 2014) to state the 
following actions.
    <bullet> Doing the repair or preventive modification of the frame 
at station 328 terminates the applicable repetitive inspection 
requirements.
    <bullet> Doing the preventive modification of the frame at station 
360 terminates the applicable station 360 inspection requirements.
    <bullet> Doing the repair or preventive modification of the frame 
at station 328, and doing the preventive modification of the frame at 
station 360 terminates the applicable repetitive inspection 
requirements of the frame at station 344, and the Boeing Alert Service 
Bulletin 737-53A1323, dated December 6, 2013, skin inspections.
    Boeing stated that the proposed wording in paragraphs (i) and (j) 
of the proposed AD (79 FR 36672, June 30, 2014) is not clear. Boeing 
stated that inspections of the frame at station 328 or at station 360 
can be terminated by a single action (applicable repair or 
modification). Boeing explained that accomplishing both specified 
actions at station 328 and station 360 terminates the station 344 frame 
inspections and the option 2 skin inspections.
    We agree to clarify the acceptable terminating actions. We have 
added new paragraph (m) of this AD, which provides the following 
terminating actions. We have redesignated subsequent paragraphs 
accordingly.
    <bullet> Accomplishing the repair or preventive modification of the 
frame at station 328 terminates the inspections of that frame required 
by paragraphs (i), (j), and (k) of this AD.
    <bullet> Accomplishing the repair or preventive modification of the 
frame at station 328 and the preventive modification of the frame at 
station 360, terminates the inspections of the frame at station 344 and 
the fuselage skin inspections required by paragraphs (i) and (j) of 
this AD.
    <bullet> Accomplishing the repair or preventive modification of the 
frame at station 360 terminates the inspections of that frame required 
by paragraphs (i) and (j) of this AD.
    <bullet> Accomplishing the repair or preventive modification of the 
frame at station 328 terminates the fuselage skin inspections and the 
station 328 frame inspections required by paragraphs (i) and (j) of 
this AD.

Recommendation To Specify Optional Preventive Modification

    Boeing recommended that we specify in paragraphs (i) and (j) of the 
proposed AD (79 FR 36672, June 30, 2014) that the station 328 repair 
described in Boeing Alert Service Bulletin 737-53A1323, dated December 
6, 2013, can be used as an optional preventive modification.
    We partially agree with the commenter's request. The commenter's 
request is already addressed in the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1323, dated December 6, 2013. 
However, additional text might help clarify this provision. We have 
added additional text to paragraphs (i), (j), and (k) of this AD that 
operators may do the repair of the frame at station 328, as specified 
in paragraph (m) of this AD, as an optional preventive modification for 
that frame.

Requests To Revise Paragraph Format and Inspection Method

    Boeing requested that we revise paragraphs (i) and (j) of the 
proposed AD (79 FR 36672, June 30, 2014) by moving the requirements for 
Group 6 airplanes to a new paragraph. Boeing stated that the service 
information for Group 6 airplanes provides directed inspection 
instructions for the station 328 frame only, as provided in table 5 of 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-
53A1323, dated December 6, 2013. Boeing added that for Group 6 
airplanes, there are no directed inspections for station 344 or station 
360, but there are related investigative and corrective actions for 
detailed inspections of the frame at station 312 and station 344.
    Southwest Airlines (SWA) requested that we specify that the frame 
at station 344 requires detailed inspections, not detailed and eddy 
current inspections. SWA stated that Boeing Alert Service Bulletin 737-
53A1323, dated December 6, 2013, describes only detailed inspections at 
station 344.
    We partially agree with both commenters. We disagree with making 
the changes requested by the commenters. However, we agree that certain 
actions are only done at certain locations and for certain airplanes. 
The inspections at station 344 are detailed inspections only. 
Application of the

[[Page 73951]]

appropriate inspection method to a given frame is addressed by the 
phrase ``as applicable,'' i.e., actions are applicable to the frames 
identified in the service information for each group of airplane. We 
have revised paragraphs (i)(1), (i)(2)(i), (i)(2)(ii), (j)(l), and 
(j)(2) of this AD by adding ``as applicable'' after the station 
locations. This revision clarifies that those actions are done only as 
specified in the service information.

Request To Add Sub-Paragraph Headers

    Boeing requested that we add the subtitles ``Initial Inspections'' 
and ``Follow-on Inspections'' to paragraphs (i)(1) and (i)(2), 
respectively, of the proposed AD (79 FR 36672, June 30, 2014). Boeing 
also requested that we change the wording in paragraph (i)(2) the 
proposed AD to ``Accomplishing the follow[hyphen]on inspections 
required by paragraph (i)(2) of this AD,'' instead of ``Accomplishing 
the initial inspections . . . '' Boeing stated that paragraph (i) of 
the proposed AD would mandate the inspections for airplanes with fewer 
than 28,300 total flight cycles, where compliance (tables 4, 7, and 8 
of paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1323, dated December 6, 2013) consists of initial inspections 
and then follow-on inspections that contain options. Boeing explained 
that paragraph (i)(1) of the proposed AD would mandate the initial 
inspections, and paragraph (i)(2) of the proposed AD would mandate the 
follow-on inspections. Boeing also explained that paragraph (i)(2) of 
the proposed AD phrase ``accomplishing the initial inspections'' is 
understood to refer to the first follow-on inspection directed by the 
compliance time (threshold).
    We do not agree with the commenter's request. Paragraph (i)(2) of 
this AD follows the format of Boeing's service bulletin compliance 
tables, which has a different repeat interval from the inspections 
specified in paragraph (i)(1) of this AD. Paragraphs (i)(1) and (i)(2) 
of this AD contain both initial and repetitive inspections as well as 
related investigative actions. We have not changed this AD in this 
regard.

Request To Revise Repetitive Inspection Wording

    Boeing requested that we revise the last sentence of paragraph 
(i)(2)(ii) of the proposed AD (79 FR 36672, June 30, 2014) to state, 
``Repeat the inspections specified in this paragraph thereafter . . . 
'' Boeing stated that this wording would then match the wording for the 
repetitive inspections specified in paragraph (i)(2)(i) of the proposed 
AD.
    We agree with the commenter's request. In this case, similar 
wording will provide consistent paragraph wording without changing the 
intent of the NPRM (79 FR 36672, June 30, 2014). We have revised the 
wording in paragraph (i)(2)(ii) of this AD to ``Repeat the inspections 
specified in this paragraph thereafter at the applicable time and 
intervals specified in . . . .''

Request To Clarify a Certain Compliance Time

    Europe Airpost requested that, in order to avoid any confusion, we 
clearly state a compliance time for paragraph (j) of the proposed AD 
(79 FR 36672, June 30, 2014) for airplanes that have 28,300 total 
flight cycles or more. The commenter asked whether those airplanes 
would fall under the condition 28,300 total flight cycles but less than 
32,800 total flight cycles, or 32,800 total flight cycles or more.
    We agree that clarification is necessary. In this case, paragraph 
(j) of this AD states to use the applicable times specified in tables 
4, 5, 7, and 8, of paragraph 1.E., ``Compliance,'' of Boeing Alert 
Service Bulletin 737-53A1323, dated December 6, 2013. Individual 
airplanes within an operator's fleet could fall into different 
categories and thus have different compliance times. Operators are to 
use the appropriate compliance times and repetitive intervals based 
upon the applicable number of total flight cycles that have been 
accumulated on each airplane as of the effective date of this AD. We 
have added new paragraph (n)(3) of the AD to inform operators that the 
``Condition'' columns of the compliance tables also contain compliance 
information that corresponds to the effective date of the AD. We have 
also revised paragraphs (i)(1) and (j)(1) of this AD to refer to 
paragraph (n)(3) of this AD.

Request To Clarify Terminating Action Wording

    SWA requested that we revise the terminating action portion of 
paragraph (j) of the proposed AD (79 FR 36672, June 30, 2014) to 
clarify the specified actions. SWA stated that, as written, the 
terminating action statement seems to imply that the operator is 
required to accomplish both the preventive modification of the frame at 
station 360 and the repair of the frame at station 328 to terminate the 
repetitive inspection requirements for any of the station 328, 344, and 
360 frames. SWA also stated that the terminating action in paragraph 
(j) of the proposed AD does not specify actions or terminating actions 
if a repair is installed at the station 344 frame. SWA explained that 
Boeing Alert Service Bulletin 737-53A1323, dated December 6, 2013, 
contains terminating action in the footnotes of the compliance tables 
in paragraph 1.E., ``Compliance,'' which the commenter thinks should be 
restated in the AD.
    We agree with the commenter's request. For clarity, we have moved 
the terminating action provisions that were specified in paragraphs 
(i)(1), (i)(2), (j), and (k) of the proposed AD (79 FR 36672, June 30, 
2014) to new paragraphs (m)(1) through (m)(4) of this AD. We have 
redesignated subsequent paragraphs accordingly.

Requests To Specify Eddy Current Inspection

    Europe Airpost requested that we clarify whether we meant to 
exclude the eddy current inspection at station 328 described in Boeing 
Alert Service Bulletin 737-53A1323, dated December 6, 2013, in 
paragraph (k) of the proposed AD (79 FR 36672, June 30, 2014). Boeing 
requested that we add the eddy current inspection at station 328 
described in Boeing Alert Service Bulletin 737-53A1323, dated December 
6, 2013, in paragraph (k) of the proposed AD.
    We agree with Boeing's request to specify the eddy current 
inspection and Europe Airpost's request to clarify the eddy current 
inspection requirement. We inadvertently omitted the eddy current 
inspection from paragraph (k) of the proposed AD (79 FR 36672, June 30, 
2014) which applies to Group 7 airplanes. Our intention was to match 
the actions described in Boeing Alert Service Bulletin 737-53A1323, 
dated December 6, 2013. In the NPRM (79 FR 36672, June 30, 2014), we 
did not identify any differences with Boeing Alert Service Bulletin 
737-53A1323, dated December 6, 2013, in regards to the required 
inspections, which includes repetitive eddy current inspections at 
station 328. For Groups 2 through 7 airplanes, paragraphs (i) and (j) 
of the proposed AD do specify detailed and HFEC inspections for Groups 
2 through 6 airplanes. Therefore, we have revised paragraph (k) of this 
AD to specify doing eddy current inspections, in addition to the 
detailed inspections, of the frame at station 328 for Group 7 
airplanes.

Request To Specify Terminating Actions for Station 380

    SWA requested that we specify procedures or terminating actions for 
repairs installed at the station 380 frame, since paragraph (l) of the 
proposed AD (79 FR 36672, June 30, 2014) does not specify such actions.

[[Page 73952]]

    We do not agree with the commenter's request. Boeing has not 
provided such repairs for our approval in Boeing Alert Service Bulletin 
737-53A1323, dated December 6, 2013. Therefore, we have no specific 
engineering data to review and approve. We have not changed this AD in 
this regard.

Request for Credit for Certain Repairs

    SWA requested that we revise paragraphs (i) through (l) of the 
proposed AD (79 FR 36672, June 30, 2014) to include provisions for 
existing repairs that were done using the service repair manual (SRM) 
or the original equipment manufacturer (OEM) instructions. SWA 
requested that the NPRM be revised to either terminate the inspections 
or include alternative actions if existing repairs inhibit the ability 
to perform the inspections.
    We partially agree with the commenter's request. We agree that 
repairs approved by Boeing via FAA Form 8100-9 (Statement of Compliance 
with Airworthiness Standards) would have also included the appropriate 
inspections. We disagree that SRM repairs would necessarily provide the 
same level of safety. The commenter did not specify for which SRM 
repairs it was requesting approval. Such repairs might or might not 
have included consideration of the safety issues addressed by Boeing 
Alert Service Bulletin 737-53A1323, dated December 6, 2013, and this AD 
(e.g., skin cracking combined with frame cracking). We have added a new 
paragraph (p) to this AD to provide credit for repairs of the station 
328, 344, 360, and 380 frames in the areas addressed by this AD that 
have been approved by the Boeing ODA via FAA Form 8100-9 prior to the 
effective date of this AD for the repairs specified in paragraphs (i), 
(j), (k), and (l) of this AD. We have redesignated subsequent 
paragraphs accordingly.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
this AD with the changes described previously and minor editorial 
changes. We have determined that these minor changes:
    <bullet> Are consistent with the intent that was proposed in the 
NPRM (79 FR 36672, June 30, 2014) for correcting the unsafe condition; 
and
    <bullet> Do not add any additional burden upon the public than was 
already proposed in the NPRM (79 FR 36672, June 30, 2014).
    We also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this AD.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Alert Service Bulletin 737-53A1323, dated 
December 6, 2013. The service information describes procedures for 
inspection for cracking and missing straps, modification, and repair of 
certain fuselage frames. This service information is reasonably 
available because the interested parties have access to it through 
their normal course of business or by the means identified in the 
ADDRESSES section of this AD.

Costs of Compliance

    We estimate that this AD affects 417 airplanes of U.S. registry.
    We estimate the following costs to comply with this AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                  Cost on U.S.
             Action                     Labor cost           Parts cost     Cost per product       operators
----------------------------------------------------------------------------------------------------------------
Inspections....................  21 work-hours x $85 per              $0   $1,785 per          $744,345 per
                                  hour = $1,785 per                         inspection cycle.   inspection
                                  inspection cycle.                                             cycle.
----------------------------------------------------------------------------------------------------------------

    We have received no definitive data that would enable us to provide 
cost estimates for certain on-condition actions specified in this AD. 
However, we estimate the following costs to do any necessary repairs of 
the station 328 frame and the station 360 frame. 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
----------------------------------------------------------------------------------------------------------------
Frame 328 repair......................  25 work-hours x $85 per hour =  Negligible..............          $2,125
                                         $2,125.
Frame 360 repair......................  5 work-hours x $85 per hour =   Negligible..............             425
                                         $425.
----------------------------------------------------------------------------------------------------------------

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII: Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701: ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD will not have a substantial direct effect on the States, 
on the relationship between the national government and the States, or 
on the distribution of power and responsibilities among the various 
levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979),
    (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.

[[Page 73953]]

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2015-23-08 The Boeing Company: Amendment 39-18324; Docket No. FAA-
2014-0436; Directorate Identifier 2014-NM-010-AD.

(a) Effective Date

    This AD is effective January 4, 2016.

(b) Affected ADs

    None.

(c) Applicability

    (1) This AD applies to The Boeing Company Model 737-100, -200, -
200C, -300, -400, and -500 series airplanes, certificated in any 
category, as identified in Boeing Alert Service Bulletin 737-
53A1323, dated December 6, 2013.
    (2) Installation of Supplemental Type Certificate (STC) 
ST01219SE (http://rgl.faa.gov/Regulatory_and_Guidance_Library/
rgstc.nsf/0/ebd1cec7b301293e86257cb30045557a/$FILE/ST01219SE.pdf) 
does not affect the ability to accomplish the actions required by 
this AD. Therefore, for airplanes on which STC ST01920SE is 
installed, a ``change in product'' alternative method of compliance 
(AMOC) approval request is not necessary to comply with the 
requirements of 14 CFR 39.17.

(d) Subject

    Air Transport Association (ATA) of America Code 53, Fuselage.

(e) Unsafe Condition

    This AD was prompted by reports of cracks in fuselage frames, 
and a report of a missing strap that was not installed on a fuselage 
frame during production. We are issuing this AD to detect and 
correct missing fuselage frame straps and frame cracking that can 
result in severed frames. Continued operation of the airplane with 
multiple adjacent severed frames, or the combination of a severed 
frame and fuselage skin chemical mill cracks, can result in 
uncontrolled decompression of the airplane.

(f) Compliance

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

(g) Actions for Group 1 Airplanes

    For airplanes identified as Group 1 in Boeing Alert Service 
Bulletin 737-53A1323, dated December 6, 2013: At the applicable time 
specified in table 1 of paragraph 1.E., ``Compliance,'' of Boeing 
Alert Service Bulletin 737-53A1323, dated December 6, 2013, except 
as provided by paragraph (n)(1) of this AD, do the inspection for 
cracking of the frames and applicable repairs using a method 
approved in accordance with the procedures specified in paragraph 
(q) of this AD.

(h) Groups 2 Through 7 Airplanes: Inspection for Strap Installation at 
Station 312

    For airplanes identified as Groups 2 through 7 in Boeing Alert 
Service Bulletin 737-53A1323, dated December 6, 2013: At the 
applicable time specified in tables 2 and 3 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1323, dated 
December 6, 2013, except as provided by paragraph (n)(1) of this AD, 
do a general visual inspection of the frame at station 312 to 
determine if the strap adjacent to stringer S-22 right is installed, 
in accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1323, dated December 6, 2013. If the strap 
is not installed, before further flight, repair using a method 
approved in accordance with the procedures specified in paragraph 
(q) of this AD.

(i) Groups 2 Through 6 Airplanes With Less Than 28,300 Total Flight 
Cycles: Repetitive Inspections, Related Investigative Actions, and 
Corrective Actions at Stations 328, 344, and 360

    For airplanes identified as Groups 2 through 6 in Boeing Alert 
Service Bulletin 737-53A1323, dated December 6, 2013, that have 
accumulated less than 28,300 total flight cycles as of the effective 
date of this AD: Do the actions required by paragraphs (i)(1) and 
(i)(2) of this AD. Operators may do the repair of the frame at 
station 328 as specified in paragraph (m) of this AD as an optional 
preventive modification for that frame.
    (1) At the applicable times specified in tables 4, 5, 7, and 8 
of paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1323, dated December 6, 2013, except as provided by 
paragraphs (n)(1) and (n)(3) of this AD: Do detailed and eddy 
current inspections of the frame at stations 328, 344, and 360, as 
applicable, for cracking or a severed frame web; and do all 
applicable related investigative and corrective actions; in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1323, dated December 6, 2013, except as 
specified in paragraph (n)(2) of this AD. Do all applicable related 
investigative and corrective actions before further flight. Repeat 
the applicable inspections thereafter at the applicable time and 
intervals specified in paragraph 1.E., ``Compliance,'' of Boeing 
Alert Service Bulletin 737-53A1323, dated December 6, 2013, until 
the inspection required by paragraph (i)(2) of this AD is done.
    (2) At the applicable time specified in tables 4, 5, 7, and 8 of 
paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1323, dated December 6, 2013, do the actions specified in 
paragraph (i)(2)(i) or (i)(2)(ii) of this AD. Accomplishing the 
initial inspections required by paragraph (i)(2) of this AD 
terminates the inspections required by paragraph (i)(1) of this AD.
    (i) Do detailed and eddy current inspections of the frame at 
stations 328, 344, and 360, as applicable, for cracking or a severed 
frame web; and do all applicable related investigative and 
corrective actions; in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1323, dated 
December 6, 2013, except as specified in paragraph (n)(2) of this 
AD. Do all applicable related investigative and corrective actions 
before further flight. Repeat the inspections specified in this 
paragraph thereafter at the applicable time and intervals specified 
in paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1323, dated December 6, 2013.
    (ii) Do detailed and eddy current inspections of the frame at 
stations 328, 344, and 360, as applicable, for cracking or a severed 
frame web; and external detailed and eddy current inspections of the 
fuselage skin for cracking; and do all applicable related 
investigative and corrective actions; in accordance with the 
Accomplishment Instructions of Boeing Alert Service Bulletin 737-
53A1323, dated December 6, 2013, except as specified in paragraph 
(n)(2) of this AD. Do all applicable related investigative and 
corrective actions before further flight. Repeat the inspections 
specified in this paragraph thereafter at the applicable time and 
intervals specified in paragraph 1.E., ``Compliance,'' of Boeing 
Alert Service Bulletin 737-53A1323, dated December 6, 2013.

(j) Groups 2 Through 6 Airplanes With 28,300 Total Flight Cycles or 
More: Repetitive Inspections, Related Investigative Actions, and 
Corrective Actions at Stations 328, 344, and 360

    For airplanes identified as Groups 2 through 6 in Boeing Alert 
Service Bulletin 737-53A1323, dated December 6, 2013, that have 
accumulated 28,300 total flight cycles or more as of the effective 
date of this AD: At the applicable times specified in tables 4, 5, 
7, and 8 of paragraph 1.E., ``Compliance,'' of Boeing Alert Service 
Bulletin 737-53A1323, dated December 6, 2013, except as provided by 
paragraphs (n)(1) and (n)(3) of this AD, do the inspections 
specified in paragraph (j)(1) or (j)(2) of this AD; and do all 
applicable related investigative and corrective actions; in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1323, dated December 6, 2013, except as 
specified in paragraph (n)(2) of this AD. Do all applicable related 
investigative and corrective actions before further flight. Repeat 
the applicable inspections specified in paragraph (j)(1) or

[[Page 73954]]

(j)(2) of this AD thereafter at the applicable time and intervals 
specified in paragraph 1.E., ``Compliance,'' of Boeing Alert Service 
Bulletin 737-53A1323, dated December 6, 2013. Operators may do the 
repair of the frame at station 328, as specified in paragraph (m) of 
this AD, as an optional preventive modification for that frame.
    (1) Do detailed and eddy current inspections of the frame at 
stations 328, 344, and 360, as applicable, for cracking or a severed 
frame web.
    (2) Do detailed and eddy current inspections of the frame at 
stations 328, 344, and 360, as applicable, for cracking or a severed 
frame web; and external detailed and eddy current inspections of the 
fuselage skin for cracking.

(k) Group 7 Airplanes: Repetitive Inspections, Related Investigative 
Actions, and Corrective Actions at Station 328

    For airplanes identified as Group 7 in Boeing Alert Service 
Bulletin 737-53A1323, dated December 6, 2013: At the applicable time 
specified in table 6 of paragraph 1.E., ``Compliance,'' of Boeing 
Alert Service Bulletin 737-53A1323, dated December 6, 2013, except 
as provided by paragraph (n)(1) of this AD, do a detailed inspection 
and eddy current inspection of the frame at station 328 for cracking 
or a severed frame web; and do all applicable related investigative 
and corrective actions; in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1323, dated 
December 6, 2013, except as specified in paragraph (n)(2) of this 
AD. Do all applicable related investigative and corrective actions 
before further flight. Repeat the inspections specified in this 
paragraph thereafter at the applicable time and intervals specified 
in paragraph 1.E., ``Compliance,'' of Boeing Alert Service Bulletin 
737-53A1323, dated December 6, 2013. Operators may do the repair of 
the frame at station 328, as specified in paragraph (m) of this AD, 
as an optional preventive modification for that frame.

(l) Groups 2 Through 5 Airplanes: Repetitive Inspections, Related 
Investigative Actions, and Corrective Actions at Station 380

    For airplanes identified as Groups 2 through 5 in Boeing Alert 
Service Bulletin 737-53A1323, dated December 6, 2013: At the 
applicable time specified in tables 9 and 10 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1323, dated 
December 6, 2013, except as provided by paragraph (n)(1) of this AD, 
do detailed and eddy current inspections of the frame at station 380 
for cracking or a severed frame web; and do all applicable 
corrective actions; in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1323, dated 
December 6, 2013, except as specified in paragraph (n)(2) of this 
AD. Do all applicable corrective actions before further flight. 
Repeat the inspections specified in this paragraph thereafter at the 
applicable time and intervals specified in paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1323, dated 
December 6, 2013.

(m) Terminating Actions for Airplanes Identified as Groups 2, 3, 4, 5, 
6, and 7

    (1) For airplanes identified as Groups 2, 3, 4, 5, and 7 in 
Boeing Alert Service Bulletin 737-53A1323, dated December 6, 2013: 
Accomplishing the repair or preventive modification of the frame at 
station 328, in accordance with the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1323, dated December 6, 2013, 
except as required by paragraph (n)(2) of this AD, terminates the 
inspections of that frame required by paragraphs (i), (j), and (k) 
of this AD.
    (2) For airplanes identified as Groups 2, 3, 4, and 5 in Boeing 
Alert Service Bulletin 737-53A1323, dated December 6, 2013: 
Accomplishing the repair or preventive modification of the frame at 
station 328 and the preventive modification of the frame at station 
360, in accordance with the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1323, dated December 6, 2013, except 
as required by paragraph (n)(2) of this AD, terminates the 
inspections of the frame at station 344 and the fuselage skin 
inspections required by paragraphs (i) and (j) of this AD.
    (3) For airplanes identified as Groups 2, 3, 4, and 5 in Boeing 
Alert Service Bulletin 737-53A1323, dated December 6, 2013: 
Accomplishing the repair or preventive modification of the frame at 
station 360, in accordance with the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1323, dated December 6, 2013, 
except as required by paragraph (n)(2) of this AD, terminates the 
inspections of that frame required by paragraphs (i) and (j) of this 
AD.
    (4) For airplanes identified as Group 6 in Boeing Alert Service 
Bulletin 737-53A1323, dated December 6, 2013: Accomplishing the 
repair or preventive modification of the frame at station 328, in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1323, dated December 6, 2013, except as 
required by paragraph (n)(2) of this AD, terminates the fuselage 
skin inspections and the station 328 frame inspections required by 
paragraphs (i) and (j) of this AD.

(n) Exceptions to Service Information

    (1) Where Boeing Alert Service Bulletin 737-53A1323, dated 
December 6, 2013, specifies a compliance time after the ``original 
issue date of this service bulletin,'' this AD requires compliance 
within the specified compliance time after the effective date of 
this AD.
    (2) If any cracking is found during any inspection required by 
this AD, and Boeing Alert Service Bulletin 737-53A1323, dated 
December 6, 2013, specifies to contact Boeing for appropriate 
action: Before further flight, repair the cracking using a method 
approved in accordance with the procedures specified in paragraph 
(q) of this AD.
    (3) The Condition column of Tables 4, 5, 7, and 8 in paragraph 
1.E., ``Compliance,'' of Boeing Alert Service Bulletin 737-53A1323, 
dated December 6, 2013, refers to total flight cycles ``at the 
original issue date of this service bulletin.'' This AD, however, 
applies to the airplanes with the specified total flight cycles as 
of the effective date of this AD.

(o) Post-Repair Inspections and Post-Modification Inspections

    (1) The post-repair and post-modification inspections specified 
in tables 13 through 15 of paragraph 1.E., ``Compliance,'' of Boeing 
Alert Service Bulletin 737-53A1323, dated December 6, 2013, are not 
required by this AD.
    (2) The post-repair and post-modification inspections specified 
in Tables 13 through 15 of paragraph 1.E., ``Compliance,'' of Boeing 
Alert Service Bulletin 737-53A1323, dated December 6, 2013, may be 
used in support of compliance with section 121.1109(c)(2) or 
129.109(b)(2) of the Federal Aviation Regulations (14 CFR 
121.1109(c)(2) or 14 CFR 129.109(b)(2)). The corresponding actions 
specified in the Accomplishment Instructions of Boeing Alert Service 
Bulletin 737-53A1323, dated December 6, 2013, are not required by 
this AD.

(p) Credit for Previous Actions

    This paragraph provides credit for repairs of the station 328, 
344, 360, and 380 frames in the areas addressed by this AD that have 
been approved by the Boeing Organization Designation Authorization 
(ODA) via FAA Form 8100-9 (Statement of Compliance with 
Airworthiness Standards) prior to the effective date of this AD for 
the repairs specified in paragraphs (i), (j), (k), and (l) of this 
AD.

(q) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Los Angeles 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 paragraph (r) of this AD. 
Information may be emailed 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 
that has been authorized by the Manager, Los Angeles 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.

(r) Related Information

    For more information about this AD, contact Galib Abumeri, 
Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles 
Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, 
CA 90712-4137; phone: 562-627-5324; fax: 562-627-5210; email: 
[email protected].

(s) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference

[[Page 73955]]

(IBR) of the service information listed in this paragraph under 5 
U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless this AD specifies otherwise.
    (i) Boeing Alert Service Bulletin 737-53A1323, dated December 6, 
2013.
    (ii) Reserved.
    (3) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-
5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com.
    (4) You may view this service information at the FAA, Transport 
Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For 
information on the availability of this material at the FAA, call 
425-227-1221.
    (5) You may view this service information that is incorporated 
by reference 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 30, 2015.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2015-28824 Filed 11-25-15; 8:45 am]
 BILLING CODE 4910-13-P

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