[Federal Register Volume 84, Number 93 (Tuesday, May 14, 2019)]
[Proposed Rules]
[Pages 21279-21282]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-09866]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0323; Product Identifier 2019-NM-026-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 737-800 series airplanes. This 
proposed AD was

[[Page 21280]]

prompted by reports of inadequate clearance between a certain fuel 
quantity indicating system (FQIS) tank unit and a certain reinforcement 
angle upon accomplishment of a certain modification. This proposed AD 
would require a detailed inspection to measure the clearance between 
the FQIS tank unit and a certain reinforcement angle, and repair if 
necessary. We are proposing this AD to address the unsafe condition on 
these products.

DATES: We must receive comments on this proposed AD by June 28, 2019.

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 Aviation 
Partners Boeing, 2811 S 102nd Street, Suite 200, Seattle, WA 98168; 
telephone 206-830-7699; internet https://www.aviationpartnersboeing.com. You may view this 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.

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-2019-
0323; or in person at 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 Docket Operations (phone: 800-647-
5527) is listed above. Comments will be available in the AD docket 
shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Christopher Baker, Aerospace Engineer, 
Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des 
Moines, WA 98198; phone and fax: 206-231-3552; email: 
christopher.r.baker@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-2019-0323; 
Product Identifier 2019-NM-026-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 NPRM.

Discussion

    We have received reports of inadequate clearance between an FQIS 
tank unit at rib 21 and the stringer U-14 reinforcement angle upon 
accomplishment of the split scimitar winglet modification of 
supplemental type certificate (STC) ST00830SE. Following alterations or 
maintenance in this area, the FQIS tank unit and the stringer U-14 
reinforcement angle must maintain a minimum 0.10-inch clearance, as 
specified in Aviation Partners Boeing (APB) Service Bulletin AP737-57-
020, dated April 5, 2018. A Boeing design change led to interference 
between the FQIS tank unit and the winglet structure upon installation 
of STC ST00830SE. STC ST00830SE, combined with the Boeing FQIS bracket 
configuration on certain airplanes, leads to inadequate clearance or 
interference between the structure and the FQIS tank unit in the 
outboard area of the wing tanks. APB notified Boeing of the 
nonconformance when APB was unable to meet the clearance requirements 
upon installation of the STC ST00830SE on two separate modifications. 
Such inadequate clearance, if not addressed, could result in a 
potential source of ignition in a fuel tank, consequent fire, 
overpressure, and structural failure of the wing.
    An ignition in the fuel tank could result from either of two 
scenarios. In one scenario, if the lightning protection shield over the 
out-of-tank FQIS wiring has a degraded or missing connection to the 
structure, excessive current can be induced in the FQIS wiring during a 
lightning strike, resulting in high voltage between the fuel probe and 
the structure. This high voltage from lightning-induced current, 
combined with inadequate clearance of the probe from the structure, 
could result in arcs and sparks in the fuel tank. A degraded or missing 
lightning protection shield connection to the structure is identified 
as a latent failure.
    In the second scenario, electrical sparks could occur if there is a 
hot short between power wiring and out-of-tank FQIS wiring, when 
combined with surface coatings that are worn as a result of a probe 
that has been in contact with the structure. A probe in contact with 
the structure would likely remain latent for a significant period of 
time with worn coatings before actual metal-to-metal contact was made, 
at which time the FQIS indication for that tank would blank, eventually 
resulting in the need for troubleshooting.

Related Service Information Under 1 CFR Part 51

    We reviewed Aviation Partners Boeing Service Bulletin AP737-57-020, 
dated April 5, 2018. This service information describes procedures for 
a detailed inspection to measure the clearance between the FQIS tank 
unit and stringer U-14 reinforcement angle at rib 21 (WSTA 617) on the 
left-hand wing, and repair including trimming the stringer U-14 
reinforcement angle to obtain minimum clearance. 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.

Costs of Compliance

    We estimate that this proposed AD affects 16 airplanes of U.S. 
registry. We estimate the following costs to comply with this proposed 
AD:

[[Page 21281]]



                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Detailed Inspection...................  7 work-hours x $85 per                $0            $595          $9,520
                                         hour = $595.
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    We estimate the following costs to do any necessary repair 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 this 
repair:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                    Action                                 Labor cost               Parts cost        product
----------------------------------------------------------------------------------------------------------------
Repair........................................  4 work-hours x $85 per hour =                 $0            $340
                                                 $340.
----------------------------------------------------------------------------------------------------------------

    According to the manufacturer, some or all of the costs of this 
proposed AD may be covered under warranty, thereby reducing the cost 
impact on affected individuals. We do not control warranty coverage for 
affected individuals. As a result, we have included all known costs in 
our cost estimate.

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 and associated appliances 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-2019-0323; Product Identifier 
2019-NM-026-AD.

(a) Comments Due Date

    We must receive comments by June 28, 2019.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 737-800 series 
airplanes, certificated in any category, line numbers 4919 through 
5063 inclusive, modified by supplemental type certificate (STC) 
ST00830SE.

(d) Subject

    Air Transport Association (ATA) of America Code 28, Fuel.

(e) Unsafe Condition

    This AD was prompted by reports of inadequate clearance between 
a certain fuel quantity indicating system (FQIS) tank unit and a 
certain reinforcement angle upon accomplishment of a certain 
modification. We are issuing this AD to address this condition, 
which could result in a potential source of ignition in a fuel tank 
and consequent fire, overpressure, and structural failure of the 
wing and possible loss of the airplane.

(f) Compliance

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

(g) Inspection and Repair

    Within 18 months after the effective date of this AD: Perform a 
detailed inspection to determine the clearance between the FQIS tank 
unit at rib 21 (WSTA 617) and stringer U-14 reinforcement angle in 
accordance with the Accomplishment Instructions of Aviation Partners 
Boeing Service Bulletin AP737-57-020, dated April 5, 2018. If the 
measured clearance is less than 0.10-inch: Before further flight, 
perform the repair action in accordance with the Accomplishment 
Instructions of Aviation Partners Boeing Service Bulletin AP737-57-
020, dated April 5, 2018.

[[Page 21282]]

(h) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle 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 (i)(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 Branch, FAA, 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.

(i) Related Information

    (1) For more information about this AD, contact Christopher 
Baker, Aerospace Engineer, Propulsion Section, FAA, Seattle ACO 
Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 
206-231-3552; email: christopher.r.baker@faa.gov.
    (2) For service information identified in this AD, contact 
Aviation Partners Boeing, 2811 S 102nd Street, Suite 200, Seattle, 
WA 98168; telephone 206-830-7699; internet https://www.aviationpartnersboeing.com. You may view this 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 Des Moines, Washington, on May 3, 2019.
Michael Kaszycki,
Acting Director, System Oversight Division, Aircraft Certification 
Service.
[FR Doc. 2019-09866 Filed 5-13-19; 8:45 am]
BILLING CODE 4910-13-P


