DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0114; Product Identifier 2018-NM-146-AD; Amendment
39-19680; AD 2019-14-02]
RIN 2120-AA64

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) for all
The Boeing Company Model 737 series airplanes. This AD was prompted by
a report that structural fatigue cracks can develop in certain aluminum
pressure module check valves prior to the design limit. This AD
requires an inspection to determine the part numbers of the four
hydraulic systems A and B pressure module check valves and applicable
on-condition actions. The FAA is issuing this AD to address the unsafe
condition on these products.

DATES: This AD is effective August 27, 2019.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of August 27,
2019.

ADDRESSES: For service information identified in this final rule,
contact Boeing Commercial Airplanes, Attention: Contractual & Data
Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA
90740-5600; phone: 562-797-1717; internet: https://www.myboeingfleet.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 http://www.regulations.gov
by searching for and locating Docket No. FAA-2019-0114.

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-
0114 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: Douglas Tsuji, Senior Aerospace
Engineer, Systems and Equipment Section, FAA, Seattle ACO Branch, 2200
South 216th St., Des Moines, WA 98198; phone and fax: 206-231-3548;
email: douglas.tsuji@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to all The Boeing Company
Model 737 series airplanes. The NPRM published in the Federal Register
on March 1, 2019 (84 FR 6981). The NPRM was prompted by a report that
structural fatigue cracks can develop in certain aluminum pressure
module check valves prior to the design limit. The NPRM proposed to
require an inspection to determine the part numbers of the four
hydraulic systems A and B pressure module check valves and applicable
on-condition actions.
The FAA is issuing this AD to address structural fatigue cracks in
certain aluminum pressure module check valves, which could cause
separation of the check valve head from the check valve body when
hydraulic pressure is applied, resulting in injuries to maintenance
personnel.

Comments

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

Two commenters supported the NPRM. United Airlines (UAL) agreed
with the need for the NPRM. A private citizen also expressed support
for the NPRM, but added that cost should not be an issue in relation to
airplane safety, the cost of the proposed rule is especially low, and
that the FAA has an ethical duty to protect the public by adopting the
proposed rule.

Effect of Winglets on Accomplishment of the Proposed Actions

Aviation Partners Boeing stated that the installation of winglets
per Supplemental Type Certificate (STC) ST00830SE or STC ST01219SE does
not affect the accomplishment of the manufacturer's service
instructions.
The FAA agrees with the commenter that STC ST00830SE and STC
ST01219SE do not affect the accomplishment of the manufacturer's
service instructions. Therefore, the installation of STC ST00830SE or
STC ST01219SE does not affect the ability to accomplish the actions
required by this AD. The FAA has not changed this AD in this regard.

Request To Change Applicability of the NPRM

UAL requested that the FAA change the proposed applicability from
including all The Boeing Company Model 737-8 and 737-9 airplanes, to
use the effectivity specified in Boeing Special Attention Requirements
Bulletin 737-29-1126 RB, dated October 2, 2018, which specifies The
Boeing Company Model 737-8 and 737-9 airplanes, line numbers 5602
through 7050. UAL mentioned that Boeing Special Attention Service
Bulletin 737-29-1126, dated October 2, 2018, states that ``Airplanes
after line number 7050 cannot use Parker check valves as an optional
part,'' and that this statement is counter to the applicability stated
in the NPRM. UAL stated the understanding of this statement to be that
The Boeing Company Model 737-8 and 737-9 airplanes, line number 7051
and later were delivered without part number (P/N) H61C0552M1; that the
illustrated parts catalog (IPC) does not authorize installation of that
part after delivery; and that omission from the IPC should ensure
unapproved parts are not installed on The Boeing Company Model 737-8
and 737-9 airplanes, line number 7051 and later; therefore providing an
acceptable level of safety.
The FAA disagrees with the request to change the applicability of
this AD. The FAA does not control or approve the Boeing IPC, and P/N
H61C0552M1 is considered a rotable part. Therefore, the FAA has
determined that these parts could later be installed on airplanes that
were initially delivered with acceptable parts, making those airplanes
subject to the unsafe condition. The FAA has not changed this AD in
this regard.

Conclusion

The FAA reviewed the relevant data, considered the comments
received, and determined that air safety and the public interest
require adopting this final rule as proposed, except for minor
editorial changes. The FAA has determined that these minor changes:
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.

Related Service Information Under 1 CFR Part 51

The FAA reviewed the following service information.
Boeing Special Attention Requirements Bulletin 737-29-1123
RB, dated October 2, 2018.
Boeing Special Attention Requirements Bulletin 737-29-1126
RB, dated October 2, 2018.
Boeing Special Attention Requirements Bulletin 737-29-1127
RB, dated October 8, 2018.
The service information describes procedures for an inspection to
determine the part numbers of the four hydraulic systems A and B
pressure module check valves and applicable on-condition actions. On-
condition actions include replacement of Parker pressure module check
valves, P/N H61C0552M1, with Crissair pressure module check valves, P/N 1C4196.
These documents are distinct since they apply to different airplane
models.
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 1,747 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs for Required Actions

The FAA estimates the following costs to do any necessary on-
condition actions (per check valve replacement) that would be required.
The FAA has no way of determining the number of aircraft that might
need these on-condition actions:

Estimated Costs of On-Condition Actions

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
rulemaking action.
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.

Regulatory Findings

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
Order 12866,
(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
reference, Safety.

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
directive (AD):