
[Federal Register Volume 81, Number 119 (Tuesday, June 21, 2016)]
[Proposed Rules]
[Pages 40208-40210]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-14295]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-6901; Directorate Identifier 2015-NM-192-AD]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain The Boeing Company Model 737-600, -700, -700C, -800, and -900 
series airplanes. This proposed AD was prompted by an evaluation by the 
design approval holder (DAH) indicating that the aft pressure bulkhead 
is subject to widespread fatigue damage (WFD). This proposed AD would 
require repetitive inspections of the aft pressure bulkhead web for any 
cracking, crack indications, discrepant fastener holes, and corrosion; 
and corrective actions if necessary. We are proposing this AD to detect 
and correct cracks in the aft pressure bulkhead web, which could result 
in an uncontrolled decompression of the fuselage.

DATES: We must receive comments on this proposed AD by August 5, 2016.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, 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 NPRM, 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-2016-6901.

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-2016-
6901; 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 
(ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-
6450; fax: 425-917-6590; email: Alan.Pohl@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2016-6901; 
Directorate Identifier 2015-NM-192-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

    Fatigue damage can occur locally, in small areas or structural 
design details, or globally, in widespread areas. Multiple-site damage 
is widespread damage that occurs in a large structural element such as 
a single rivet line of a lap splice joining two large skin panels. 
Widespread damage can also occur in multiple elements such as adjacent 
frames or stringers. Multiple-site damage and multiple-element damage 
cracks are typically too small initially to be reliably detected with 
normal inspection methods. Without intervention, these cracks will 
grow, and eventually compromise the structural integrity of the 
airplane. This condition is known as widespread fatigue damage. It is 
associated with general degradation of large areas of structure with 
similar structural details and stress levels. As an airplane ages, WFD 
will likely occur, and will certainly occur if the airplane is operated 
long enough without any intervention.
    The FAA's WFD final rule (75 FR 69746, November 15, 2010) became 
effective on January 14, 2011. The WFD rule requires certain actions to 
prevent structural failure due to WFD throughout the operational life 
of certain existing transport category airplanes and all of these 
airplanes that will be certificated in the future. For existing and 
future airplanes subject to the WFD rule, the rule requires that DAHs 
establish a limit of validity (LOV) of the engineering data that 
support the structural maintenance program. Operators affected by the 
WFD rule may not fly an airplane beyond its LOV, unless an extended LOV 
is approved.
    The WFD rule (75 FR 69746, November 15, 2010) does not require 
identifying and developing maintenance actions if the DAHs can show 
that such actions are not necessary to prevent WFD before the airplane 
reaches the

[[Page 40209]]

LOV. Many LOVs, however, do depend on accomplishment of future 
maintenance actions. As stated in the WFD rule, any maintenance actions 
necessary to reach the LOV will be mandated by airworthiness directives 
through separate rulemaking actions. In the context of WFD, this action 
is necessary to enable DAHs to propose LOVs that allow operators the 
longest operational lives for their airplanes, and still ensure that 
WFD will not occur. This approach allows for an implementation strategy 
that provides flexibility to DAHs in determining the timing of service 
information development (with FAA approval), while providing operators 
with certainty regarding the LOV applicable to their airplanes.
    Analysis by the DAH has determined that the aft pressure bulkhead 
web at the Y chord is susceptible to WFD for certain Model 737-600, -
700, -700C, -800, and -900 series airplanes. This analysis indicates 
that the repetitive inspection intervals mandated by AD 2005-21-06, 
Amendment 39-14344 (70 FR 61226, October 21, 2005), should be reduced 
at the WFD threshold to detect cracking due to WFD. This cracking, if 
left undetected, could result in an uncontrolled decompression of the 
fuselage.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Alert Service Bulletin 737-53A1248, Revision 2, 
dated October 14, 2015. The service information describes procedures 
for low frequency eddy current, or high frequency eddy current, and 
detailed inspections of the bulkhead web for cracking, crack 
indications, discrepant fastener holes, and corrosion. 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.

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 these same type 
designs.

Proposed AD Requirements

    This proposed AD would require accomplishing the actions specified 
in the service information described previously, except as discussed 
under ``Differences Between this Proposed AD and the Service 
Information.''
    The phrase ``corrective actions'' is used in this NPRM. Corrective 
actions correct or address any condition found. Corrective actions in 
an AD could include, for example, repairs.

Differences Between This Proposed AD and the Service Information

    Boeing Alert Service Bulletin 737-53A1248, Revision 2, dated 
October 14, 2015, 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:
     In accordance with a method that we approve; or
     Using data that meet the certification basis of the 
airplane, and that have been approved by the Boeing Commercial 
Airplanes Organization Designation Authorization (ODA) whom we have 
authorized to make those findings.

Costs of Compliance

    We estimate that this proposed AD affects 680 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
            Action                       Labor cost               Cost per product       Cost on U.S. operators
----------------------------------------------------------------------------------------------------------------
Inspections..................  34 work-hours x $85 per hour   $2,890 per inspection     $1,965,200 per
                                = $2,890 per inspection        cycle.                    inspection cycle.
                                cycle.
----------------------------------------------------------------------------------------------------------------

    We have received no definitive data that would enable us to provide 
cost estimates for the on-condition actions specified in this proposed 
AD.

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 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 this 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

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):


[[Page 40210]]


The Boeing Company: Docket No. FAA-2016-6901; Directorate Identifier 
2015-NM-192-AD.

(a) Comments Due Date

    We must receive comments by August 5, 2016.

(b) Affected ADs

    Certain requirements of this AD terminate certain requirements 
of AD 2005-21-06, Amendment 39-14344 (70 FR 61226, October 21, 2005) 
(``AD 2005-21-06'').

(c) Applicability

    This AD applies to The Boeing Company Model 737-600, -700, -
700C, -800, and -900 series airplanes, certificated in any category, 
line number 1 through 1755, as identified in Boeing Alert Service 
Bulletin 737-53A1248, Revision 2, dated October 14, 2015.

(d) Subject

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

(e) Unsafe Condition

    This AD was prompted by an evaluation by the design approval 
holder (DAH) indicating that the aft pressure bulkhead is subject to 
widespread fatigue damage (WFD). We are issuing this AD to detect 
and correct cracks in the aft pressure bulkhead web, which could 
result in an uncontrolled decompression of the fuselage.

(f) Compliance

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

(g) Repetitive Inspections

    At the applicable time specified in paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1248, 
Revision 2, dated October 14, 2015, or within 18 months after 
November 25, 2005 (the effective date of AD 2005-21-06), whichever 
occurs later: Do a low frequency eddy current (LFEC) or high 
frequency eddy current (HFEC) inspection, and a detailed inspection, 
of the aft and forward sides, as applicable, of the aft pressure 
bulkhead web at the Y chord, above and below stringer S-15L and 
stringer S-15R, to detect discrepancies (including cracking, crack 
indications, discrepant fastener holes, and corrosion), in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-53A1248, Revision 2, dated October 14, 2015. 
Access and restoration procedures specified in the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1248, Revision 
2, dated October 14, 2015, are not required by this AD. Operators 
may do those procedures following their maintenance practices.
    (1) If no discrepancy is found: Repeat the inspections 
thereafter at the applicable times specified in paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1248, 
Revision 2, dated October 14, 2015.
    (2) If any discrepancy is found: Do the actions specified in 
paragraphs (g)(2)(i) and (g)(2)(ii) of this AD.
    (i) Repair the discrepancy before further flight using a method 
approved in accordance with the procedures specified in paragraph 
(j) of this AD.
    (ii) On areas that are not repaired, repeat the inspections 
thereafter at the applicable times specified in paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1248, 
Revision 2, dated October 14, 2015.

(h) Terminating Action for AD 2005-21-06

    Accomplishment of the initial inspections required by paragraph 
(g) of this AD terminates the requirements of AD 2005-21-06.

(i) Credit for Previous Actions

    This paragraph provides credit for the actions specified in 
paragraph (g) of this AD, if those actions were performed before the 
effective date of this AD using Boeing Alert Service Bulletin 737-
53A1248, dated September 9, 2004; or Boeing Alert Service Bulletin 
737-53A1248, Revision 1, dated September 10, 2007; which are not 
incorporated by reference in this AD.

(j) Alternative Methods of Compliance (AMOCs)

    (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 paragraph (k)(1) of this AD. 
Information may be emailed to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
    (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, modification, or alteration 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. To be approved, the 
repair method, modification deviation, or alteration deviation must 
meet the certification basis of the airplane, and the approval must 
specifically refer to this AD.

(k) Related Information

    (1) For more information about this AD, contact Alan Pohl, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office (ACO), 1601 Lind Avenue SW., Renton, WA 98057-
3356; phone: 425-917-6450; fax: 425-917-6590; email: 
Alan.Pohl@faa.gov.
    (2) 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.

    Issued in Renton, Washington, on June 3, 2016.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2016-14295 Filed 6-20-16; 8:45 am]
 BILLING CODE 4910-13-P


