DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2019-0323; Product Identifier 2019-NM-026-AD; Amendment
39-19785; AD 2019-22-06]
Airworthiness Directives; The Boeing Company Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
SUMMARY: The FAA is adopting a new airworthiness directive (AD)
certain The Boeing Company Model 737-800 series airplanes. This AD was
prompted by reports of inadequate clearance between a certain fuel
quantity indicating system (FQIS) tank unit and a certain reinforcement
angle added as a part of a certain split winglet modification. This AD
requires a detailed inspection to measure the clearance between the
FQIS tank unit and a certain reinforcement angle installed as a part of
the split winglet modification, and repair if necessary. The FAA is
issuing this AD to address the unsafe condition on these products.
DATES: This AD is effective December 30, 2019.
The Director of the Federal Register approved the incorporation by
reference of a certain publications listed in this AD as of December
ADDRESSES: For service information identified in this final rule,
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. It is also available on the internet at https://www.
regulations.gov by searching for and locating Docket No. FAA-2019-0323.
Examining the AD Docket
You may examine the AD docket on the internet at https://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 final rule, the regulatory evaluation, any comments received, and
other information. The address for Docket Operations is U.S. Department
of Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
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:
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to certain The Boeing
Company Model 737-800 series airplanes. The NPRM published in the
Federal Register on May 14, 2019 (84 FR 21279). The NPRM was prompted
by reports of inadequate clearance between a FQIS tank unit at rib 21
and the stringer U-14 reinforcement angle added as a part of a split
winglet modification per supplemental type certificate (STC) ST00830SE.
The NPRM proposed to require a detailed inspection to measure the
clearance between the FQIS tank unit and a certain reinforcement angle
installed as a part of the split winglet modification, and repair if
The FAA is issuing this AD to address inadequate clearance between
a certain FQIS tank unit and a certain reinforcement angle upon
accomplishment of a certain split winglet modification, 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.
The FAA gave the public the opportunity to participate in
developing this final rule. The following presents the comments
received on the NPRM and the FAA's response to each comment.
Support for the NPRM
United Airlines stated that it concurs with the proposed actions
with no additional comments.
Request To Clarify Paragraph (c) Applicability of the Proposed AD
Boeing and Aviation Partners Boeing (APB) requested that we revise
paragraph (c) of the proposed AD to include more detail as to which
airplanes are affected. Boeing explained that STC ST00830SE has
multiple configurations, and the proposed AD is applicable to only one
configuration; airplanes in that configuration are identified in
Aviation Partners Boeing Service Bulletin AP737-57-020, dated April 5,
2018. APB clarified further that STC ST00830SE includes both blended
and split scimitar winglet configurations, but operators with aircraft
modified to receive the blended winglets do not install the
reinforcement that may interfere with the tank unit, and are not
subject to the unsafe condition and requirements of the proposed AD.
The FAA agrees with the commenters' request for the reasons
provided. The FAA has revised paragraph (c) of this AD to state that
this AD applies to The Boeing Company Model 737-800 series airplanes,
certificated in any category, line numbers 4919 through 5063 inclusive,
modified with split winglets per STC ST00830SE and listed in Aviation
Partners Boeing Service Bulletin AP737-57-020, dated April 5, 2018.
Request To Delete ODA Provisions
Boeing and APB requested that the FAA delete paragraph (h)(3) of
the proposed AD because The Boeing Company Organization Designation
Authorization (ODA) does not have AMOC authority for the referenced
split scimitar winglet STC ST00830SE.
The FAA agrees with the request for the reasons provided. The FAA
has removed paragraph (h)(3) of this AD.
Request To Clarify the Cost of Compliance Section of the NPRM
Boeing requested that the FAA revise the Cost of Compliance section
of the NPRM to clarify that APB is responsible for warranty coverage.
Boeing reasoned that the NPRM's language of ``according to the
manufacturer . . .'' did not specify which manufacturer, Boeing or APB,
would be responsible for warranty coverage.
The FAA agrees with the request for the reasons provided. The FAA
has revised the Costs of Compliance section of this final rule to
clarify that APB is the manufacturer responsible for warranty coverage.
Request To Revise the Summary of the NPRM
Boeing requested that the FAA revise the SUMMARY section of the
NPRM to further clarify which airplanes are affected by the proposed
AD. Boeing suggested that the FAA add ``modified with split winglets
and listed in Aviation Partners Boeing Service Bulletin AP737-57-020,
dated April 5, 2018,'' as a qualifier for the airplanes affected. In
addition, Boeing requested that the FAA clarify what prompted the AD
and the requirements of the AD by adding language that makes clear the
reinforcement angle was added as a part of the referenced split
scimitar winglet STC ST00830SE.
The FAA partially agrees with the request. The FAA disagrees with
the request to add the qualifying statement of ``modified with split
winglets and listed in Aviation Partners Boeing Service Bulletin AP737-
57-020, dated April 5, 2018,'' because the SUMMARY section serves only
as a brief introduction to the NPRM, and the level of detail requested
by Boeing is reserved for the Regulatory Section of the proposed AD. As
discussed earlier, the FAA has revised paragraph (c) of this AD to
clarify that this AD applies only to The Boeing Company Model 737-800
series airplanes modified with split winglets per STC ST00830SE and
listed in Aviation Partners Boeing Service Bulletin AP737-57-020, dated
April 5, 2018. However, the FAA has revised the SUMMARY section of the
final rule to clarify that a certain reinforcement angle was added as
part of a certain split winglet modification.
The FAA agrees with Boeing's request to clarify what prompted the
NPRM and the requirements of the NPRM, for the reasons provided. The
SUMMARY section of this AD has been revised accordingly.
The FAA reviewed the relevant data, considered the comments
received, and determined that air safety and the public interest
require adopting this final rule with the changes described previously
and minor editorial changes. The FAA has determined that these minor
Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.
The FAA also determined that these changes will not increase the
economic burden on any operator or increase the scope of this final
Related Service Information Under 1 CFR Part 51
The FAA 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 at rib 21 (WSTA 617) and stringer U-14 reinforcement
angle 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.
Costs of Compliance
The FAA estimates that this AD affects 16 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:
||7 work-hours x $85 per hour =
The FAA estimates the following costs
to do any necessary repair
that would be required based on the results of the inspection. The FAA
has no way of determining the number of aircraft that might need this
||4 work-hours x $85 per hour =
According to Aviation Partners Boeing,
some or all of the costs of
this AD may be covered under warranty, thereby reducing the cost impact
on affected individuals. The FAA does not control warranty coverage for
affected individuals. As a result, the FAA has included all known costs
in the agency's 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.
The FAA is 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
This 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.
This AD will not have federalism implications under Executive Order
13132. This AD will 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 this AD:
(1) Is not a ``significant regulatory action'' under Executive
(2) Will not affect intrastate aviation in Alaska, and
(3) 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
Adoption of the Amendment
Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 14 CFR part 39 as follows:
PART 39--AIRWORTHINESS DIRECTIVES
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]
2. The FAA amends Sec. 39.13 by adding the following new airworthiness