Document ID: FAA-2014-0772-0001
Agency: faa
Document Type: Proposed Rule
Title: Airworthiness Directives: The Boeing Company Airplanes
Posted Date: 2014-11-17T05:00Z

[Federal Register Volume 79, Number 221 (Monday, November 17, 2014)]
[Proposed Rules]
[Pages 68381-68384]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-27070]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2014-0772; Directorate Identifier 2014-NM-090-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 supersede Airworthiness Directive (AD) 2011-08-
51, which applies to certain The Boeing Company Model 737-300, -400, 
and -500 series airplanes. AD 2011-08-51 currently requires repetitive 
inspections of the lap joint at certain stringers along the entire 
length from certain body stations. Since we issued AD 2011-08-51, an 
evaluation by the design approval holder (DAH) has determined that the 
lower fastener holes in the lower skin of the fuselage lap splice are 
subject to widespread fatigue damage (WFD), and as a result the DAH 
specified revised compliance times, an expanded inspection area, and 
additional inspections for cracks and open pockets, and corrective 
actions if necessary. Additionally, this evaluation has also determined 
that the repetitive inspection interval can be increased for lap 
splices with certain new fay scratches. This proposed AD would expand 
the inspection area, require additional inspections for cracks and open 
pockets, and corrective actions if necessary, and revise the compliance 
times. We are proposing this AD to detect and correct fatigue cracking 
of the lower fastener holes in the lower skin of the fuselage lap 
splice, which could result in reduced structural integrity of the 
airplane.

DATES: We must receive comments on this proposed AD by January 2, 2015.

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 proposed 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.

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-
0772; 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

[[Page 68382]]

ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

FOR FURTHER INFORMATION CONTACT: Wayne Lockett, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office 
(ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-
6447; fax: 425-917-6590; email: wayne.lockett@faa.gov.

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-2014-0772; 
Directorate Identifier 2014-NM-090-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

    Structural fatigue damage is progressive. It begins as minute 
cracks, and those cracks grow under the action of repeated stresses. 
This can happen because of normal operational conditions and design 
attributes, or because of isolated situations or incidents such as 
material defects, poor fabrication quality, or corrosion pits, dings, 
or scratches. Fatigue damage can occur locally, in small areas or 
structural design details, or globally. Global fatigue damage is 
general degradation of large areas of structure with similar structural 
details and stress levels. Multiple-site damage is global damage that 
occurs in a large structural element such as a single rivet line of a 
lap splice joining two large skin panels. Global 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, in a condition known as 
widespread fatigue damage (WFD). 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 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.
    On May 6, 2011, we issued AD 2011-08-51, Amendment 39-16701 (76 FR 
28632, May 18, 2011), for certain The Boeing Company Model 737-300, -
400, and -500 series airplanes. AD 2011-08-51 requires repetitive 
external eddy current inspections of the lap joints at stringers S-4R 
and S-4L, from body station (BS) 360 to BS 908. If a crack indication 
is found, AD 2011-08-51 requires either confirming the crack by doing 
internal eddy current inspections, or repairing the crack. As an 
alternative to the external eddy current inspections, AD 2011-08-51 
provides for internal eddy current and detailed inspections for cracks 
in the lower skin at the lower row of fasteners at stringers S-4L and 
S-4R. AD 2011-08-51 resulted from a report indicating that a Model 737-
300 series airplane experienced a rapid decompression when the lap 
joint at stringer S-4L between BS 664 and BS 727 cracked and opened up 
due to cracking in the lower skin at the lower row of fasteners. We 
issued AD 2011-08-51 to detect and correct such cracking, which could 
result in an uncontrolled decompression of the airplane.

Actions Since AD 2011-08-51, Amendment 39-16701 (76 FR 28632, May 18, 
2011), Was Issued

    Since we issued AD 2011-08-51, Amendment 39-16701 (76 FR 28632, May 
18, 2011), an evaluation by the DAH has determined that the lower 
fastener holes in the lower skin of the fuselage lap splice are subject 
to WFD, and as a result the DAH specified revised compliance times, an 
expanded inspection area, and additional inspections for cracks and 
open pockets, and corrective actions if necessary. Additionally, this 
evaluation has also determined that the repetitive inspection interval 
can be increased for lap splices with certain new fay scratches.

Relevant Service Information

    We reviewed Boeing Alert Service Bulletin 737-53A1319, Revision 2, 
dated April 4, 2014. For information on the procedures and compliance 
times, see this service information at http://www.regulations.gov by 
searching for and locating Docket No. FAA-2014-0772.

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

    Although this proposed AD does not explicitly restate the 
requirements of AD 2011-08-51, Amendment 39-16701 (76 FR 28632, May 18, 
2011), this proposed AD would retain certain requirements of AD 2011-
08-51. Those requirements are referenced in the service information 
identified previously, which, in turn, are referenced in paragraphs (g) 
and (l) of this proposed AD. This proposed AD would require 
accomplishing the actions specified in the service information 
described previously, except as discussed under ``Differences Between 
the Proposed AD and the Service Information.''

[[Page 68383]]

Differences Between This Proposed AD and the Service Information

    Boeing Alert Service Bulletin 737-53A1319, Revision 2, dated April 
4, 2014, specifies to contact the manufacturer for instructions on how 
to inspect and 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.

Interim Action

    We consider this proposed AD interim action. An investigation is 
ongoing and no terminating action has been developed. Once terminating 
action is developed, approved, and available, we might consider 
additional rulemaking.

Costs of Compliance

    We estimate that this proposed AD affects 130 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                 Estimated Costs
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                                                                                                  Cost on U.S.
             Action                    Labor cost            Parts cost      Cost per product      operators
----------------------------------------------------------------------------------------------------------------
Repetitive inspections [actions  6 or 4,270 work-hours   None.............  $510 or $362,950   $66,300 or
 retained from AD 2011-08-51,     (depending on                              per inspection     $47,183,500 per
 Amendment 39-16701 (76 FR        inspection method) x                       cycle.             inspection
 28632, May 18, 2011)].           $85 per work-hour =                                           cycle.
                                  $510 or $362,950 per
                                  inspection cycle.
Repetitive inspections [new      4 or 550 work-hours     None.............  $340 or 46,750     $44,200 or
 proposed action].                (depending on                              per inspection     $6,077,500 per
                                  inspection method) x                       cycle.             inspection
                                  $85 per hour = $340                                           cycle.
                                  or 46,750 per
                                  inspection cycle.
One-time inspections [new        5,370 work-hours x $85  None.............  $456,450.........  $59,338,500.
 proposed action].                per hour = $456,450.
----------------------------------------------------------------------------------------------------------------

    We have received no definitive data that would enable us to provide 
a 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 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

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. Amend Sec.  39.13 by removing Airworthiness Directive (AD) 2011-08-
51, Amendment 39-16701 (76 FR 28632, May 18, 2011), and adding the 
following new AD:

The Boeing Company: Docket No. FAA-2014-0772; Directorate Identifier 
2014-NM-090-AD.

(a) Comments Due Date

    The FAA must receive comments on this AD action by January 2, 
2015.

(b) Affected ADs

    This AD replaces AD 2011-08-51, Amendment 39-16701 (76 FR 28632, 
May 18, 2011).

(c) Applicability

    This AD applies to The Boeing Company Model 737-300, -400, and -
500 series airplanes, certificated in any category, as identified in 
Boeing Alert Service Bulletin 737-53A1319, Revision 2, dated April 
4, 2014.

(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) that has determined that the lower fastener holes in 
the lower skin of the fuselage lap splice are subject to widespread 
fatigue damage (WFD). We are issuing this AD to detect and correct 
fatigue cracking of the lower fastener holes in the lower skin of 
the fuselage lap splice, which could result in reduced structural 
integrity of the airplane.

(f) Compliance

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

[[Page 68384]]

(g) Repetitive Inspections for Crack Indications at Stringers S-4R and 
S-4L, Body Station (BS) 360 to BS 908

    At the applicable time specified in Table 1 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1319, 
Revision 2, dated April 4, 2014: Do an external eddy current 
inspection, or internal eddy current and detailed inspections, for 
crack indications at stringers S-4R and S-4L, from body station (BS) 
360 to BS 908, except as provided by paragraph (h) of this AD, in 
accordance with Part 1 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1319, Revision 2, dated April 4, 2014. 
Repeat the inspection(s) thereafter at the applicable intervals 
specified in Table 1 or Table 2, as applicable, of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1319, 
Revision 2, dated April 4, 2014. Either inspection option may be 
used at any repetitive inspection cycle.

(h) One-Time Inspections for Cracks at Stringers S-4L and S-4R, BS 360 
to BS 908

    At the applicable time specified in Table 3 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1319, 
Revision 2, dated April 4, 2014, except as required by paragraph (m) 
of this AD: Do one-time internal detailed and eddy current 
inspections for cracks at stringers S-4R and S-4L, from BS 360 to BS 
908, in accordance with Part 2 of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 737-53A1319, Revision 2, dated April 
4, 2014. Accomplishment of the inspections required by this 
paragraph does not terminate the repetitive inspections required by 
paragraph (g) of this AD.

(i) One-Time Inspections for Cracks at Stringer S-4R, BS 908 to BS 1016

    For airplanes identified as Group 2, 3, 5, and 7 in Boeing Alert 
Service Bulletin 737-53A1319, Revision 2, dated April 4, 2014: At 
the applicable time specified in Table 4 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1319, 
Revision 2, dated April 4, 2014, except as required by paragraph (m) 
of this AD, do one-time internal detailed and eddy current 
inspections for cracks at stringer S-4R, from BS 908 to BS 1016, in 
accordance with Part 3 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1319, Revision 2, dated April 4, 2014.

(j) Repetitive Inspections for Cracks at Stringer S-4R, BS 908 to BS 
1016

    For airplanes identified as Group 2, 3, 5, and 7 in Boeing Alert 
Service Bulletin 737-53A1319, Revision 2, dated April 4, 2014: At 
the applicable time specified in Table 5 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1319, 
Revision 2, dated April 4, 2014, except as required by paragraph (m) 
of this AD, do external eddy current inspections, or internal eddy 
current and detailed inspections, for cracks at stringer S-4R, from 
BS 908 to BS 1016, in accordance with Part 4 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-53A1319, Revision 
2, dated April 4, 2014. Repeat the inspection(s) thereafter at the 
applicable intervals specified in Table 5 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1319, 
Revision 2, dated April 4, 2014. Either inspection option may be 
used at any repetitive inspection cycle.

(k) General Visual Inspection for Open Pockets at Stringer S-4R, BS 908 
to BS 1016

    For airplanes identified as Group 1, 4, and 6 in Boeing Alert 
Service Bulletin 737-53A1319, Revision 2, dated April 4, 2014: At 
the applicable time specified in Table 6 of paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-53A1319, 
Revision 2, dated April 4, 2014, except as required by paragraph (m) 
of this AD, do a general visual inspection for open pockets of the 
lower skin panel at stringer S-4R, from BS 908 to BS 1016, in 
accordance with Part 5 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-53A1319, Revision 2, dated April 4, 2014. 
If any open pocket is found, before further flight, inspect and 
repair using a method approved in accordance with the procedures 
specified in paragraph (o) of this AD.

(l) Corrective Action

    If any crack is found during any inspection required by this AD: 
Before further flight, repair using a method approved in accordance 
with the procedures specified in paragraph (o) of this AD. 
Accomplishment of repairs approved in accordance with the procedures 
specified in paragraph (o) of this AD terminates the repetitive 
inspections specified in paragraphs (g) and (j) of this AD in the 
repaired areas only.

(m) Service Information Exception

    Where Boeing Alert Service Bulletin 737-53A1319, Revision 2, 
dated April 4, 2014, specifies a compliance time ``after the 
Revision 2 date of this service bulletin,'' this AD requires 
compliance within the specified compliance time after the effective 
date of this AD.

(n) Credit for Previous Actions

    This paragraph provides credit for actions required by paragraph 
(g) of this AD, if those actions were performed before the effective 
date of this AD using Boeing Alert Service Bulletin 737-53A1319, 
dated April 4, 2011; or Boeing Alert Service Bulletin 737-53A1319, 
Revision 1, dated April 8, 2011. Boeing Alert Service Bulletin 737-
53A1319, dated April 4, 2011, is incorporated by reference in AD 
2011-08-51, Amendment 39-16701 (76 FR 28632, May 18, 2011). Boeing 
Alert Service Bulletin 737-53A1319, Revision 1, dated April 8, is 
not incorporated by reference in this AD.

(o) 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 (p)(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 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 2011-08-51, Amendment 39-16701 (76 FR 
28632, May 18, 2011), are approved as AMOCs for the corresponding 
provisions of paragraphs (g) and (l) of this AD.

(p) Related Information

    (1) For more information about this AD, contact Wayne Lockett, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office (ACO), 1601 Lind Avenue SW., Renton, WA 98057-
3356; phone: 425-917-6447; fax: 425-917-6590; email: 
wayne.lockett@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 November 5, 2014.
Jeffrey E. Duven,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2014-27070 Filed 11-14-14; 8:45 am]
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