DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-9432; Directorate Identifier 2016-NM-116-AD;
Amendment 39-18922; AD 2017-12-07]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain
The Boeing Company Model 737-800, -900, and -900ER series airplanes.
This AD was prompted by reports of in-flight failure of the left
temperature control valve and control cabin trim air modulating valve.
This AD requires replacing the left temperature control valve and
control cabin trim air modulating valve. We are issuing this AD to
address the unsafe condition on these products.

DATES: This AD is effective July 20, 2017.

The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of July 20, 2017.

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; telephone 562-797-1717; 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-2016-9432.

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-
9432; 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 AD, the regulatory evaluation, any comments received, and
other information. The address for the Docket Office (phone: 800-647-
5527) is Docket Management Facility, 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: Stanley Chen, Aerospace Engineer,
Cabin Safety and Environmental Systems Branch, ANM-150S, FAA, Seattle
Aircraft Certification Office (ACO), 1601 Lind Avenue SW., Renton, WA
98057-3356; phone: 425-917-6585; fax: 425-917-6590; email:
stanley.chen@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

We 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, -900, and -900ER series airplanes. The NPRM published in
the Federal Register on December 5, 2016 (81 FR 87494). The NPRM was
prompted by reports of in-flight failure of the left temperature
control valve and control cabin trim air modulating valve. The NPRM
proposed to require replacing the left temperature control valve and
control cabin trim air modulating valve. We are issuing this AD to
prevent temperatures in excess of 100 degrees Fahrenheit in the flight
deck or the passenger cabin during cruise, which could lead to the
impairment of the flight crew and prevent continued safe flight and
landing.

Comments

We gave the public the opportunity to participate in developing
this AD. The following presents the comments received on the NPRM and
the FAA's response to each comment.

Support for the NPRM

The Air Line Pilots Association, International and United Airlines
(UAL) stated that they support the NPRM.

Request To Clarify the Unsafe Condition

Boeing requested that we change a sentence in the Discussion
section of the NPRM from "This condition, if not corrected, could
result . . . ." to "This condition, if not corrected or mitigated by
crew completion of the cabin temperature hot procedure under Section
2.8 of the quick reference handbook (QRH), could result. . . ." Boeing
stated that the cabin temperature hot procedure was created
specifically to address failed open temperature control valves. They
further stated that this procedure is an effective remedy for failed
valves and enhances safety.

We disagree with the request to revise the description of the
unsafe condition in the Discussion section. More than half of the
affected fleets are operated by non-U.S. air carriers, who are not
required to incorporate the revised Flight Crew Operations Manual
(FCOM), which includes the QRH. Since this AD does not require
incorporation of the FCOM, or the QRH, and instead requires replacement
of two control valves, we do not find it appropriate to reference the
QRH as a mitigating factor in the description of the unsafe condition.
We have not changed this AD regarding this issue.

Request To Allow Maintenance Records Review To Determine Installed Parts

Alaska Airlines (Alaska) asked that we revise paragraph (g) of the
proposed AD, which mandates replacement of certain valves, to state
that a records review is acceptable for compliance with the
requirements of that paragraph (by determining which valves must be
replaced). Alaska noted that a similar statement is included as a note
in Boeing Alert Service Bulletin 737-21A1203, dated June 8, 2016, and
that the note and steps 3.B.1.c. and 3.B.1.d. of the Accomplishment
Instructions of Boeing Alert Service Bulletin 737-21A1203, dated June
8, 2016, are not Required for Compliance (RC). (We note that those
steps state that no further action is required for nondiscrepant
parts.) Alaska indicated that because the NPRM does not include a
similar statement, an airline doing only a records check, and finding
no discrepant parts, could be considered non-compliant.

We agree with the commenter. Paragraph (g) of this AD requires
replacing certain valves in accordance with the Accomplishment
Instructions in Boeing Alert Service Bulletin 737-21A1203, dated June
8, 2016. We did not intend for operators to need an alternative method
of compliance (AMOC) to address the situation described by the
commenter. Therefore, we have revised paragraph (g) of this AD to add
the phrase "as applicable" to the requirement for valve replacements
so that operators will not need an AMOC if the correct valve is already
installed.

Request To Correct the Manufacturer Information

UAL stated that the header section of the NPRM referenced the wrong
aircraft manufacturer, reading: "Proposed Rule: Airworthiness
Directives: Bombardier, Inc. Airplanes." UAL noted that it should say
The Boeing Company Airplanes.

We acknowledge the commenter's concern. However, the NPRM correctly
identifies the manufacturer as Boeing, as published in the Federal
Register. It was the docket in the Federal Docket Management System
(FDMS) that incorrectly identified the manufacturer as Bombardier. This
information has been corrected. Therefore, we have not changed this
final rule regarding this issue.

Effect of Winglets on Accomplishment of the Proposed Actions

Aviation Partners Boeing stated that the installation of winglets
per Supplemental Type Certificate (STC)
ST00830SE does not affect the accomplishment of the manufacturer's
service instructions.

We agree with the commenter that STC ST00830SE does not affect the
accomplishment of the manufacturer's service instructions. Therefore,
the installation of STC ST00830SE does not affect the ability to
accomplish the actions required by this AD. We have not changed this AD
in this regard.

Conclusion

We reviewed the relevant data, considered the comments received,
and determined that air safety and the public interest require adopting
this AD with the change described previously and minor editorial
changes. We have determined that these minor changes:

Are consistent with the intent that was proposed in the
NPRM for correcting the unsafe condition; and

Do not add any additional burden upon the public than was
already proposed in the NPRM.

We also determined that this change will not increase the economic
burden on any operator or increase the scope of this AD.

Related Service Information Under 1 CFR Part 51

We reviewed Boeing Alert Service Bulletin 737-21A1203, dated June
8, 2016. The service information describes procedures for replacing the
left temperature control valve and control cabin trim air modulating
valve, part number 398908-4, with new part number 398908-3 or 398908-5.
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

We estimate that this AD affects 319 airplanes of U.S. registry. We
estimate the following costs to comply with this AD:

Estimated Costs

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

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) Is not a "significant rule" under 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.

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):