[Federal Register Volume 83, Number 35 (Wednesday, February 21, 2018)]
[Proposed Rules]
[Pages 7425-7428]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-03433]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2018-0112; Product Identifier 2017-NM-161-AD]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: We propose to adopt a new airworthiness directive (AD) for all 
The Boeing Company Model 737-100, -200, -200C, -300, -400, -500 series 
airplanes. This proposed AD was prompted by reports of cracking in 
certain flanges, and the adjacent web, of the wing outboard flap track 
at certain positions. This proposed AD would require an inspection to 
determine the part number of the wing outboard flap track assembly; 
repetitive inspections of each affected wing outboard flap track for 
discrepancies, and applicable on-condition actions; and repetitive 
overhaul of each wing outboard flap track. We are proposing this AD to 
address the unsafe condition on these products.

DATES: We must receive comments on this proposed AD by April 9, 2018.

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: Contractual & Data Services (C&DS), 
2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; 
telephone 562-797-1717; internet https://www.myboeingfleet.com. You may 
view this referenced service information at the FAA, Transport 
Standards Branch, 2200 South 216th St., Des Moines, WA. For information 
on the availability of this material at the FAA, call 206-231-3195. It 
is also available on the internet at http://www.regulations.gov by 
searching for and locating Docket No. FAA-2018-0112.

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-2018-
0112; or in person at the Docket Operations between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays. The AD docket contains 
this NPRM, the regulatory evaluation, any comments received, and other 
information. The street address for the Docket Operations (phone: 800-
647-5527) is listed above. Comments will be

[[Page 7426]]

available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Payman Soltani, Aerospace Engineer, 
Airframe Section, FAA, Los Angeles ACO Branch, 3960 Paramount 
Boulevard, Lakewood, CA 90712-4137; phone: 562-627-5313; fax: 562-627-
5210; 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-2018-0112; 
Product Identifier 2017-NM-161-AD'' at the beginning of your comments. 
We specifically invite comments on the overall regulatory, economic, 
environmental, and energy aspects of this NPRM. We will consider all 
comments received by the closing date and may amend this NPRM 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 a report indicating that during the tear down of a 
Model 737-300 airplane, cracking was found in the inboard lower flange 
and adjacent web near the forward attachment of the outboard flap track 
at position 8. The cracked flap track had accumulated 1,579 flight 
cycles since it was installed on the airplane after the most recent 
overhaul, and approximately 20,000 flight cycles since new. The 
metallurgical evaluation of the cracked flap track found that stress 
corrosion cracking originated from a fastener hole in the flap track 
web with missing cadmium plating. There was not sufficient evidence to 
conclude that the missing cadmium plating was the cause or the result 
of the cracking. Boeing has since received one more report of cracking 
in the outboard lower flange and the adjacent web of the outboard flap 
track at position 8 on a different Model 737-300 airplane. The crack 
was also found near the forward attachment, but did not originate from 
a fastener hole. The cracked flap track had accumulated 1,175 flight 
cycles since it was installed on the airplane. Boeing determined that 
the existing inspection programs are not sufficient to find such cracks 
before failure of a flap track could occur.
    Cracking in the area between the forward and rear spar attachments 
of the wing outboard flap tracks may lead to the inability of a 
principal structural element to sustain required flight load, such 
cracking could result in loss of the outboard trailing edge flap and 
consequent reduced controllability of the airplane.

Related Rulemaking

    AD 2013-09-02, Amendment 39-17443 (78 FR 27010, May 9, 2013) (``AD 
2013-09-02''), requires operators to use Boeing Service Bulletin (SB) 
737-57A1271, Revision 3, dated February 13, 2012 (``SB 737-57A1271 
R3''), to accomplish the inspections required by paragraph (p) of that 
AD. Boeing SB 737-57A1271 was issued to address more than 30 reports of 
stress corrosion cracks in the wing outboard flap tracks at positions 2 
and 7, and provides instructions to do detailed and non-destructive 
test (NDT) inspections of the flap track flanges and webs, and detailed 
and NDT inspections of the flap track at the rear spar attachment. 
Boeing SB 737-57A1271 also gives instructions to repair, overhaul, and 
replace the wing outboard flap tracks at positions 2 and 7. Boeing SB 
737-57A1271 does not include NDT inspections of the flap track flanges 
at the attachment of the flap transmission and the hinge support 
assembly, or NDT inspections of the flap track webs forward of the rear 
spar attachment nor repair, overhaul, and replacement of the wing 
outboard flap tracks at positions 1 and 8. As discussed above, Boeing 
reported information that indicates additional areas of stress 
corrosion cracks in other positions of the wing outboard flap tracks 
and the adjacent web of the outboard flap tracks. Therefore, the 
existing requirements of AD 2013-09-02 do not fully address the unsafe 
condition.

Related Service Information Under 1 CFR Part 51

    We reviewed Boeing Alert Requirements Bulletin 737-57A1338 RB, 
dated September 25, 2017. The service information describes procedures 
for repetitive inspections, repair, repetitive overhaul, and 
replacement of the wing outboard flap tracks, and applicable on-
condition actions. 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 new NDT inspections of the flap 
track flanges and webs forward of the rear spar attachment, in areas 
not previously inspected using SB 737-57A1271 R3 (or previous 
revisions), to the existing requirements in AD 2013-09-02. The new and 
existing requirements would also apply to the wing outboard flap tracks 
at positions 1 and 8. Accomplishment of the inspections, repair, 
overhaul, and replacement of the wing outboard flap tracks specified in 
Boeing Alert Requirements Bulletin 737-57A1338 RB, dated September 25, 
2017, would replace the instruction in SB 737-57A1271 R3 (or previous 
revisions), and terminates the requirements of AD 2013-09-02.
    This proposed AD would require accomplishment of the actions 
identified in the Boeing Alert Requirements Bulletin 737-57A1338 RB, 
dated September 25, 2017, described previously, except for any 
differences identified as exceptions in the regulatory text of this 
proposed AD.
    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-2018-0112.

Explanation of Requirements Bulletin

    The FAA worked in conjunction with industry, under the 
Airworthiness Directives Implementation Aviation Rulemaking Committee 
(AD ARC), to enhance the AD system. One enhancement is a process for 
annotating which steps in the service information are ``required for 
compliance'' (RC) with an AD. Boeing has implemented this RC concept 
into Boeing service bulletins.
    In an effort to further improve the quality of ADs and AD-related 
Boeing service information, a joint process improvement initiative was 
worked between the FAA and Boeing. The initiative resulted in the 
development of a new process in which the service information more 
clearly identifies the actions needed to address the unsafe condition 
in the ``Accomplishment Instructions.'' The new process results in a 
Boeing Requirements Bulletin, which contains only the actions needed to 
address the unsafe condition (i.e., only the RC actions).

[[Page 7427]]

Costs of Compliance

    We estimate that this proposed AD affects 160 airplanes of U.S. 
registry. We estimate the following costs to comply with this proposed 
AD:

                                      Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
                                                                                                 Cost on U.S.
             Action                     Labor cost          Parts cost     Cost per product        operators
----------------------------------------------------------------------------------------------------------------
Inspection (positions 1 and 8;   78 work-hours x $85 per              $0  $6,630 per          $1,060,800 per
 Group 2 and Group 3,             hour = $6,630 per                        inspection cycle.   inspection cycle.
 configuration 1).                inspection cycle.
Inspection (positions 1 and 8;   89 work-hours x $85 per               0  $7,565 per          $1,210,400 per
 Group 3, configuration 2).       hour = $7,565 per                        inspection cycle.   inspection cycle.
                                  inspection cycle.
Inspection (positions 2 and 7;   83 work-hours x $85 per               0  $7,055 per          $1,128,800 per
 Group 2 and Group 3,             hour = $7,055 per                        inspection cycle.   inspection cycle.
 configuration 1).                inspection cycle.
Inspection (positions 2 and 7;   86 work-hours x $85 per               0  $7,310 per          $1,169,600 per
 Group 3, configuration 2).       hour = $7,310 per                        inspection cycle.   inspection cycle.
                                  inspection cycle.
----------------------------------------------------------------------------------------------------------------

    We have received no definitive data that would enable us to provide 
cost estimates for the actions for Group 1 airplanes or 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.
    This proposed AD is issued in accordance with authority delegated 
by the Executive Director, Aircraft Certification Service, as 
authorized by FAA Order 8000.51C. In accordance with that order, 
issuance of ADs is normally a function of the Compliance and 
Airworthiness Division, but during this transition period, the 
Executive Director has delegated the authority to issue ADs applicable 
to transport category airplanes to the Director of the System Oversight 
Division.

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-2018-0112; Product Identifier 
2017-NM-161-AD.

(a) Comments Due Date

    We must receive comments by April 9, 2018.

(b) Affected ADs

    This AD affects AD 2013-09-02, Amendment 39-17443 (78 FR 27010, 
May 9, 2013) (``AD 2013-09-02'').

(c) Applicability

    This AD applies to all The Boeing Company Model 737-100, -200, -
200C, -300, -400, -500 series airplanes, certificated in any 
category.

(d) Subject

    Air Transport Association (ATA) of America Code 57, Wings.

(e) Unsafe Condition

    This AD was prompted by reports of cracking in certain flanges, 
and the adjacent web, of the wing outboard flap track at certain 
positions. We are issuing this AD to detect and correct cracking of 
the rear spar attachment, and cracking of the wing outboard flap 
tracks. Cracking in the area between the forward and rear spar 
attachments of the wing outboard flap tracks could lead to the 
inability of a principal structural element to sustain required 
flight load, and result in loss of the outboard trailing edge flap 
and consequent reduced controllability of the airplane.

(f) Compliance

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

(g) Required Actions for Group 1 Airplanes

    For airplanes identified as Group 1 in Boeing Alert Requirements 
Bulletin 737-57A1338 RB, dated September 25, 2017: Within 120 days 
after the effective date of this AD, do actions to correct the 
unsafe condition using a method approved in accordance with the 
procedures specified in paragraph (l) of this AD.

(h) Required Actions

    For airplanes not specified in paragraph (g) of this AD: Except 
as required by paragraph (i) of this AD, at the applicable times 
specified in the ``Compliance'' paragraph of Boeing Alert 
Requirements Bulletin 737-57A1338 RB, dated September 25, 2017, do 
all applicable actions identified in, and in accordance with, the 
Accomplishment Instructions of Boeing Alert Requirements

[[Page 7428]]

Bulletin 737-57A1338 RB, dated September 25, 2017.

    Note 1 to paragraph (h) of this AD: Guidance for accomplishing 
the actions required by this AD can be found in Boeing Alert Service 
Bulletin 737-57A1338, dated September 25, 2017, which is referred to 
in Boeing Alert Requirements Bulletin 737-57A1338 RB, dated 
September 25, 2017.

(i) Exceptions to Service Information Specifications

    For purposes of determining compliance with the requirements of 
this AD: Where Boeing Alert Requirements Bulletin 737-57A1338 RB, 
dated September 25, 2017, uses the phrase ``the original issue date 
of Requirements Bulletin 737-57A1338 RB,'' this AD requires using 
``the effective date of this AD.''

(j) Terminating Action for Requirements of AD 2013-09-02

    Accomplishment of the requirements specified in paragraph (h) of 
this AD terminates all of the requirements specified in AD 2013-09-
02.

(k) Parts Installation Limitation

    As of the effective date of this AD, no person may install, on 
any airplane, a wing outboard flap track having a part number listed 
in paragraph 1.B. of Boeing Alert Requirements Bulletin 737-57A1338 
RB, dated September 25, 2017, unless the inspections and corrective 
actions specified in the Accomplishment Instructions of Boeing Alert 
Requirements Bulletin 737-57A1338 RB, dated September 25, 2017, are 
accomplished prior to the part's installation on the airplane.

(l) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Los Angeles ACO Branch, 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 certification office, send it to the attention of 
the person identified in paragraph (m)(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, Los Angeles ACO Branch, 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.

(m) Related Information

    (1) For more information about this AD, contact Payman Soltani, 
Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 
3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627-
5313; fax: 562-627-5210; email: [email protected].
    (2) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Contractual & Data Services 
(C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-
5600; telephone 562-797-1717; internet https://www.myboeingfleet.com. You may view this referenced service 
information at the FAA, Transport Standards Branch, 2200 South 216th 
St., Des Moines, WA. For information on the availability of this 
material at the FAA, call 206-231-3195.

    Issued in Renton, Washington, on February 12, 2018.
Michael Kaszycki,
Acting Director, System Oversight Division, Aircraft Certification 
Service.
[FR Doc. 2018-03433 Filed 2-20-18; 8:45 am]
 BILLING CODE 4910-13-P