[Federal Register Volume 81, Number 93 (Friday, May 13, 2016)]
[Proposed Rules]
[Pages 29813-29817]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-11173]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-6664; Directorate Identifier 2015-NM-177-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) 2012-16-
07, which applies to certain Boeing Model 737-500 series airplanes. AD 
2012-16-07 currently requires inspections of the fuselage skin at the 
chem-milled steps, and repair if necessary. Since we issued AD 2012-16-
07, an evaluation by the design approval holder (DAH) indicates that 
the fuselage skin is subject to widespread fatigue damage (WFD), and we 
have received reports of cracks at the chem-milled steps in the 
fuselage skin. This proposed AD would add new fuselage skin inspections 
for cracking, inspections to detect missing or loose fasteners and any 
disbonding or cracking of bonded doublers, permanent repairs of time-
limited repairs, related investigative and corrective actions if 
necessary, and skin panel replacement. We are proposing this AD to 
detect and correct cracking on the aft lower lobe fuselage skins, which 
could result in rapid decompression of the airplane.

DATES: We must receive comments on this proposed AD by June 27, 2016.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:

[[Page 29814]]

     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-2016-6664.

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-
6664; 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: Wade Sullivan, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office 
(ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-
6430; fax: 425-917-6590; email: [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-2016-6664; 
Directorate Identifier 2015-NM-177-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 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 July 31, 2012, we issued AD 2012-16-07, Amendment 39-17154 (77 
FR 48423, August 14, 2012) (``AD 2012-16-07''), for certain The Boeing 
Company Model 737-500 series airplanes. AD 2012-16-07 requires 
inspections of the fuselage skin at the chem-milled steps, and repair 
if necessary. AD 2012-16-07 resulted from reports of chem-milled steps 
cracking on the aft lower lobe fuselage skins. We issued AD 2012-16-07 
to detect and correct cracking on the aft lower lobe fuselage skins, 
which could result in rapid decompression of the airplane.

Actions Since AD 2012-16-07 Was Issued

    Since we issued AD 2012-16-07, an evaluation by the DAH indicates 
that the lower lobe skin panels are subject to WFD, and we have 
received reports of cracks at the chem-milled steps in the fuselage 
skin.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Special Attention Service Bulletin 737-53-1315, 
Revision 1, dated June 30, 2015. The service information describes 
procedures for inspection and repair of the fuselage skin panels 
between station 727 and station 1016, and between stringers S-14 and S-
25; and also describes procedures for skin panel replacement. 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 the same type designs.

[[Page 29815]]

Proposed AD Requirements

    Although this proposed AD does not explicitly restate the 
requirements of AD 2012-16-07, this proposed AD would retain all of the 
requirements of AD 2012-16-07. Those requirements are referenced in the 
service information identified previously, which, in turn, is 
referenced in paragraphs (g) and (h) of this proposed AD.
    This proposed AD would also require accomplishing the actions 
specified in the service information described previously, except as 
discussed under ``Differences Between This Proposed AD and the Service 
Information.''
    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-2016-6664.
    The phrase ``related investigative actions'' is used in this 
proposed AD. ``Related investigative actions'' are follow-on actions 
that (1) are related to the primary actions, and (2) further 
investigate the nature of any condition found. Related investigative 
actions in an AD could include, for example, inspections.
    The phrase ``corrective actions'' is used in this proposed AD. 
``Corrective actions'' are actions that 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 Special Attention Service Bulletin 737-53-1315, Revision 1, 
dated June 30, 2015, specifies to contact the manufacturer for 
instructions on how to repair certain conditions and also to obtain 
certain work instructions, but this proposed AD would require repairing 
those conditions and also to obtain those work instructions 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.

Explanation of Compliance Time

    The compliance time for the replacement specified in this proposed 
AD for addressing WFD was established to ensure that discrepant 
structure is replaced before WFD develops in airplanes. Standard 
inspection techniques cannot be relied on to detect WFD before it 
becomes a hazard to flight. We will not grant any extensions of the 
compliance time to complete any AD-mandated service bulletin related to 
WFD without extensive new data that would substantiate and clearly 
warrant such an extension.

Costs of Compliance

    We estimate that this proposed AD affects 33 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                 Cost on U.S.
              Action                    Labor cost        Parts cost      Cost per product        operators
----------------------------------------------------------------------------------------------------------------
Inspections [actions retained      23 work-hours x $85              $0  $1,955 per           $64,515 per
 from AD 2012[dash]16[dash]07].     per hour = $1,955                    inspection cycle.    inspection cycle.
                                    per inspection
                                    cycle.
Inspections [new proposed action]  Up to 1,515                      $0  Up to $128,775 per   Up to $4,249,575
                                    work[dash]hours x                    inspection cycle.    per inspection
                                    $85 per hour =                                            cycle.
                                    $128,775 per
                                    inspection cycle.
Skin panel replacement [new        688 work[dash]hours         $96,000  $154,480...........  $5,097,840.
 proposed action].                  x $85 per hour =
                                    $58,480.
----------------------------------------------------------------------------------------------------------------

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

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
             Action                    Labor cost           Parts cost               Cost per product
----------------------------------------------------------------------------------------------------------------
Time-limited repair............  24 work-hours x $85              [\1\]   $2,040.\1\
                                  per hour = $2,040.
Permanent repair...............  31 work-hours x $85              [\1\]   $2,635.\1\
                                  per hour = $2,635.
Permanent repair inspection....  4 work-hours x $85 per           [\1\]   $340 \1\ per inspection cycle.
                                  hour = $340 per
                                  inspection cycle.
----------------------------------------------------------------------------------------------------------------
[\1\] We have received no definitive data that would enable us to provide parts 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.

[[Page 29816]]

    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. The FAA amends Sec.  39.13 by removing Airworthiness Directive (AD) 
2012-16-07, Amendment 39-17154 (77 FR 48423, August 14, 2012), and 
adding the following new AD:

The Boeing Company: Docket No. FAA-2016-6664; Directorate Identifier 
2015-NM-177-AD.

(a) Comments Due Date

    The FAA must receive comments on this AD action by June 27, 
2016.

(b) Affected ADs

    This AD replaces AD 2012-16-07, Amendment 39-17154 (77 FR 48423, 
August 14, 2012) (``AD 2012-16-07'').

(c) Applicability

    This AD applies to all The Boeing Company Model 737-500 series 
airplanes, certificated in any category.

(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 indicates that the fuselage skin is subject to 
widespread fatigue damage (WFD), and reports of cracks at the chem-
milled steps in the fuselage skin. We are issuing this AD to detect 
and correct cracking on the aft lower lobe fuselage skins, which 
could result in rapid decompression of the airplane.

(f) Compliance

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

(g) Inspections, Related Investigative and Corrective Actions

    At the applicable times specified in table 1 of paragraph 1.E., 
``Compliance,'' of Boeing Special Attention Service Bulletin 737-53-
1315, Revision 1, dated June 30, 2015, except as required by 
paragraphs (h)(1) and (h)(2) of this AD: Do the applicable 
inspections to detect cracks in the fuselage skin panels; and do all 
applicable related investigative and corrective actions; in 
accordance with the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-53-1315, Revision 1, dated June 30, 
2015, except as required by paragraphs (h)(3), (h)(4), and (h)(5) of 
this AD. Do all applicable related investigative and corrective 
actions before further flight. Repeat the applicable inspections 
thereafter at the applicable intervals specified Boeing Special 
Attention Service Bulletin 737-53-1315, Revision 1, dated June 30, 
2015. Accomplishment of a repair in accordance with ``Part 3: 
Repair'' of the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-53-1315, Revision 1, dated June 30, 
2015, except as required by paragraph (h)(3) of this AD, is 
terminating action for the repetitive inspections required by this 
paragraph at the repaired locations only.

(h) Exceptions to Boeing Special Attention Service Bulletin 737-53-
1315, Revision 1, Dated June 30, 2015

    (1) Where Boeing Special Attention Service Bulletin 737-53-1315, 
Revision 1, dated June 30, 2015, specifies compliance times ``after 
the Revision 1 date of this service bulletin,'' this AD requires 
compliance within the specified compliance times after the effective 
date of this AD.
    (2) The Condition column of table 1 of Paragraph 1.E., 
``Compliance,'' of Boeing Special Attention Service Bulletin 737-53-
1315, Revision 1, dated June 30, 2015, refers to airplanes in 
certain configurations as of the ``issue date of Revision 1 of this 
service bulletin.'' However, this AD applies to airplanes in the 
specified configurations ``as of the effective date of this AD.''
    (3) Where Boeing Special Attention Service Bulletin 737-53-1315, 
Revision 1, dated June 30, 2015, specifies contacting Boeing for 
repair instructions or work instructions, before further flight, 
repair or perform the work instructions using a method approved in 
accordance with the procedures specified in paragraph (m) of this 
AD, except as required by paragraph (h)(4) of this AD.
    (4) For airplanes on which an operator has a record that a skin 
panel was replaced with a production skin panel at or before 53,000 
total flight cycles: At the applicable time for the next inspection 
as specified in table 1 of paragraph 1.E., ``Compliance,'' Boeing 
Special Attention Service Bulletin 737-53-1315, Revision 1, dated 
June 30, 2015, except as provided by paragraphs (h)(1) and (h)(2) of 
this AD: Perform inspections and applicable corrective actions using 
a method approved in accordance with the procedures specified in 
paragraph (m) of this AD.
    (5) The Condition column of table 2 of Paragraph 1.E., 
``Compliance,'' of Boeing Special Attention Service Bulletin 737-53-
1315, Revision 1, dated June 30, 2015, refers to airplanes in 
certain configurations as of the ``issue date of Revision 1 of this 
service bulletin.'' However, this AD applies to airplanes in the 
specified configurations regardless of when the time limited repair 
is installed.

(i) Actions for Airplanes With a Time Limited Repair Installed

    For airplanes with a time limited repair installed as specified 
in Boeing Special Attention Service Bulletin 737-53-1315, dated July 
29, 2011; or Boeing Special Attention Service Bulletin, Revision 1, 
dated June 30, 2015: At the applicable times specified in table 2 of 
paragraph 1.E., ``Compliance,'' of Boeing Special Attention Service 
Bulletin 737-53-1315, Revision 1, dated June 30, 2015, except as 
provided by paragraphs (h)(1) and (h)(5) of this AD: Do the actions 
specified in paragraphs (i)(1) and (i)(2) of this AD.
    (1) Do the applicable inspections to detect missing or loose 
fasteners and any disbonding or cracking of bonded doublers; and do 
all applicable related investigative and corrective actions; in 
accordance with the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-53-1315, Revision 1, dated June 30, 
2015, except as required by paragraph (h)(3) of this AD. Do all 
applicable related investigative and corrective actions before 
further flight. Repeat the applicable inspections thereafter at the 
applicable intervals specified Boeing Special Attention Service 
Bulletin 737-53-1315, Revision 1, dated June 30, 2015.
    (2) Make the time limited repair permanent; and do all 
applicable related investigative and corrective actions; in 
accordance the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-53-1315, Revision 1, dated June 30, 
2015, except as required by paragraph (h)(3) of this AD. Do all 
applicable related investigative and corrective actions before 
further flight. Accomplishing the permanent repair required by this 
paragraph terminates the inspections required by paragraph (i)(1) of 
this AD for the permanently repaired area only.

(j) Certain Post-Repair Inspections

    For airplanes with a permanent repair installed as specified in 
Boeing Special Attention Services Bulletin 737-53-1315, Revision 1, 
dated June 30, 2015: At the applicable time specified in table 3 of 
paragraph 1.E., ``Compliance,'' of Boeing Special Attention Service 
Bulletin 737-53-1315, Revision 1, dated June 30, 2015, except as 
provided by paragraph (h)(1) of this AD: Do an external low 
frequency eddy current (LFEC) inspection for cracking of the skin at 
the critical fastener row of the repair doubler; and do all 
applicable corrective actions; in accordance the Accomplishment 
Instructions of Boeing Special Attention Service Bulletin 737-53-
1315, Revision 1, dated June 30, 2015, except as required by 
paragraph (h)(3) of this AD. Do all applicable corrective actions 
before further flight. Repeat the LFEC

[[Page 29817]]

inspection thereafter at the applicable intervals specified Boeing 
Special Attention Service Bulletin 737-53-1315, Revision 1, dated 
June 30, 2015.

(k) Skin Panel Replacement

    At the later of the times specified in paragraphs (k)(1) and 
(k)(2) of this AD: Replace the applicable skin panels, and do all 
applicable related investigative and corrective actions, in 
accordance with the Accomplishment Instructions of Boeing Special 
Attention Service Bulletin 737-53-1315, Revision 1, dated June 30, 
2015. Do all applicable related investigative and corrective actions 
before further flight. Doing the skin panel replacement required by 
this paragraph terminates the inspection requirements of paragraph 
(g) of this AD for that skin panel only, provided the skin panel 
replacement was done with a production skin panel after 53,000 total 
flight cycles.
    (1) Before 60,000 total flight cycles, but not at or before 
53,000 total flight cycles.
    (2) Within 6,000 flight cycles after the effective date of this 
AD, but not at or before 53,000 total flight cycles.

(l) Credit for Previous Actions

    This paragraph provides credit for the zone 1 actions required 
by paragraph (g) of this AD, as described in Boeing Special 
Attention Service Bulletin 737-53-1315, Revision 1, dated June 30, 
2015, if the zone 1, 2, and 3 actions, as described in Boeing 
Special Attention Service Bulletin 737-53-1315, dated July 29, 2011, 
were performed before the effective date of this AD using Boeing 
Special Attention Service Bulletin 737-53-1315, dated July 29, 2011, 
except as required by paragraph (h)(4) of this AD. Boeing Special 
Attention Bulletin 737-53-1315, dated July 29, 2011, was 
incorporated by reference in AD 2012-16-07.

(m) 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 (n)(1) 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, 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.
    (4) AMOCs approved previously for AD 2012-16-07 are approved as 
AMOCs for the corresponding provisions of paragraph (g) of this AD.

(n) Related Information

    (1) For more information about this AD, contact Wade Sullivan, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office (ACO), 1601 Lind Avenue SW., Renton, WA 98057-
3356; phone: 425-917-6430; fax: 425-917-6590; email: 
[email protected].
    (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, 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 May 5, 2016.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2016-11173 Filed 5-12-16; 8:45 am]
 BILLING CODE 4910-13-P