81 FR 28774 - Airworthiness Directives; The Boeing Company Airplanes

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration

Federal Register Volume 81, Issue 90 (May 10, 2016)

We propose to adopt a new airworthiness directive (AD) for all The Boeing Company Model 737-300, -400, and -500 series airplanes. This proposed AD was prompted by reports of intergranular cracks on the front spar chord lugs of the outboard horizontal stabilizer. This proposed AD would require repetitive inspections of the front spar chord lugs and lug bores of the horizontal stabilizer, and repair if necessary. We are proposing this AD to detect and correct cracking of the front spar chord lugs of the horizontal stabilizer. Such cracking could cause stabilizer instability, adversely affect controllability of the airplane, and adversely affect the structural integrity of the airplane.

[Federal Register Volume 81, Number 90 (Tuesday, May 10, 2016)]
[Proposed Rules]
[Pages 28774-28777]
From the Federal Register Online  [www.thefederalregister.org]
[FR Doc No: 2016-10634]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-6426; Directorate Identifier 2016-NM-023-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 all 
The Boeing Company Model 737-300, -400, and -500 series airplanes. This 
proposed AD was prompted by reports of intergranular cracks on the 
front spar chord lugs of the outboard horizontal stabilizer. This 
proposed AD would require repetitive inspections of the front spar 
chord lugs and lug bores of the horizontal stabilizer, and repair if

[[Page 28775]]

necessary. We are proposing this AD to detect and correct cracking of 
the front spar chord lugs of the horizontal stabilizer. Such cracking 
could cause stabilizer instability, adversely affect controllability of 
the airplane, and adversely affect the structural integrity of the 
airplane.

DATES: We must receive comments on this proposed AD by June 24, 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-2016-6426.

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-
6426; 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: Gaetano Settineri, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office 
(ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-
6577; 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 proposal. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2016-6426; 
Directorate Identifier 2016-NM-023-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

    We have received reports of intergranular cracks on the front spar 
chord lugs of the outboard horizontal stabilizer. The cracks have been 
found along the axis of the front spar chord and in the lug faces, lug 
bores, and lug spot-face surfaces. The stabilizer front spar chords are 
an extrusion made from 7075-T6511 aluminum. This material is 
susceptible to stress corrosion in a corrosive environment where 
residual machining stresses are present and where the material finish 
and sealant have degraded. A single joint failure will significantly 
reduce the remaining fatigue life in the rear spar. A dual failure of 
the upper and lower front spar joints of the horizontal stabilizer 
could cause stabilizer instability, adversely affect controllability of 
the airplane, and adversely affect the structural integrity of the 
airplane.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Alert Service Bulletin 737-55A1092, dated August 
7, 2015. The service information describes procedures for doing 
inspections for corrosion and cracking of the front spar chord lugs of 
the horizontal stabilizer, and inspections for corrosion of the lug 
bores. 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 design.

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. 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-2016-6426.

Differences Between This Proposed AD and the Service Information

    Boeing Alert Service Bulletin 737-55A1092, dated August 7, 2015, 
specifies to contact the manufacturer for instructions on how to repair 
certain conditions, but this 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 346 airplanes of U.S. 
registry. We estimate the following costs to comply with this proposed 
AD:

[[Page 28776]]



                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                 Cost on U.S.
             Action                     Labor cost          Parts cost     Cost per product        operators
----------------------------------------------------------------------------------------------------------------
Inspections....................  14 work-hours x $85 per              $0  $1,190 per          $411,740 per
                                  hour = $1,190 per                        inspection cycle.   inspection cycle
                                  inspection 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):

The Boeing Company: Docket No. FAA-2016-6426; Directorate Identifier 
2016-NM-023-AD.

(a) Comments Due Date

    We must receive comments by June 14, 2016.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all The Boeing Company Model 737-300, -400, 
and -500 series airplanes, certificated in any category.

(d) Subject

    Air Transport Association (ATA) of America Code 55, Stabilizers.

(e) Unsafe Condition

    This AD was prompted by reports of intergranular cracks on the 
front spar chord lugs of the outboard horizontal stabilizer. We are 
issuing this AD to detect and correct cracking of the front spar 
chord lugs of the horizontal stabilizer. Such cracking could cause 
stabilizer instability, adversely affect controllability of the 
airplane, and adversely affect the structural integrity of the 
airplane.

(f) Compliance

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

(g) Repetitive Inspections and Repairs

    Within 27 months after the effective date of this AD: Do the 
actions required by paragraphs (g)(1) and (g)(2) of this AD, and do 
all applicable repairs, in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 737-55A1092, dated 
August 7, 2015, except as required by paragraph (h) of this AD. Do 
all applicable repairs before further flight. Repeat the inspections 
specified in paragraphs (g)(1) and (g)(2) of this AD thereafter at 
the applicable intervals specified in paragraph 1.E., 
``Compliance,'' of Boeing Alert Service Bulletin 737-55A1092, dated 
August 7, 2015.
    (1) Do a detailed inspection for corrosion and an ultrasonic 
inspection for cracking of the front spar chord lugs of the left and 
right horizontal stabilizers.
    (2) Do a detailed inspection for corrosion of the lug bores of 
the front spar chord of the left and right horizontal stabilizers.

(h) Service Information Exception

    Where Boeing Alert Service Bulletin 737-55A1092, dated August 7, 
2015, specifies to contact Boeing for appropriate action, and 
specifies that action as ``RC'' (Required for Compliance): Before 
further flight, repair using a method approved in accordance with 
the procedures specified in paragraph (j) of this AD.

(i) Parts Installation Limitation

    As of the effective date of this AD: No person may install a 
replacement horizontal stabilizer on any airplane, unless the 
actions required by paragraphs (g)(1) and (g)(2) of this AD, and all 
applicable repairs are done prior to installation in accordance with 
the Accomplishment Instructions of Boeing Alert Service Bulletin 
737-55A1092, dated August 7, 2015, except as required by paragraph 
(h) of this AD. Repeat the inspections specified in paragraph (g)(1) 
and (g)(2) of this AD thereafter at the applicable intervals 
specified in paragraph 1.E., ``Compliance,'' of Boeing Alert Service 
Bulletin 737-55A1092, dated August 7, 2015.

(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: [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

[[Page 28777]]

the certification basis of the airplane, and the approval must 
specifically refer to this AD.
    (4) Except as required by paragraph (h) of this AD: For service 
information that contains steps that are labeled as RC, the 
provisions of paragraphs (j)(4)(i) and (j)(4)(ii) of this AD apply.
    (i) The steps labeled as RC, including substeps under an RC step 
and any figures identified in an RC step, must be done to comply 
with the AD. An AMOC is required for any deviations to RC steps, 
including substeps and identified figures.
    (ii) Steps not labeled as RC may be deviated from using accepted 
methods in accordance with the operator's maintenance or inspection 
program without obtaining approval of an AMOC, provided the RC 
steps, including substeps and identified figures, can still be done 
as specified, and the airplane can be put back in an airworthy 
condition.

(k) Related Information

    (1) For more information about this AD, contact Gaetano 
Settineri, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, 
Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue SW., 
Renton, WA 98057-3356; phone: 425-917-6577; 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, 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 April 28, 2016.
Dionne Palermo,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.

[FR Doc. 2016-10634 Filed 5-9-16; 8:45 am]
 BILLING CODE 4910-13-P