AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

SUMMARY: We are adopting a new airworthiness directive (AD) for certain
The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER
series airplanes. This AD was prompted by a report of installation of
incorrect wire support clamps within the bay area of the left and right
environmental control systems (ECS) during production; the ECS bay area
is a flammable fluid leakage zone. Use of incorrect wire support clamps
that are not fully cushioned could allow electrical power wiring to
come in contact with the exposed metal of the improper clamp, causing a
short circuit and subsequent electrical arcing. This AD requires inspecting to
identify the part number of the wire support clamp, and related
investigative and corrective actions if necessary. We are issuing this
AD to prevent electrical arcing and a potential ignition source, which,
in combination with flammable fuel vapors, could result in a fuel tank
explosion, and consequent loss of the airplane.

DATES: This AD is effective August 19, 2014.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of August 19,
2014.

ADDRESSES: For service information identified in this AD, contact
Boeing Commercial Airplanes, Attention: Data & Services Management,
P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-
5000, extension 1; fax 206-766-5680; 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.

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-2013-
1027; 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: Georgios Roussos, Aerospace Engineer,
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft
Certification Office, 1601 Lind Avenue SW., Renton, WA 98057-3356;
phone: 425-917-6482; fax: 425-917-6590; email:
georgios.roussos@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 737-600, -700, -700C, -800, -900, and -900ER series airplanes.
The NPRM published in the Federal Register on December 12, 2013 (78 FR
75512). The NPRM was prompted by a report of installation of incorrect
wire support clamps within the bay area of the left and right ECS
during production; the ECS bay area is a flammable leakage zone. Use of
incorrect wire support clamps that are not fully cushioned could allow
electrical power wiring to come in contact with the exposed metal of
the improper clamp, causing a short circuit and subsequent electrical
arcing. The NPRM proposed to require inspecting to identify the part
number of the wire support clamp, and related investigative and
corrective actions if necessary. We are issuing this AD to prevent
electrical arcing and a potential ignition source, which, in
combination with flammable fuel vapors, could result in a fuel tank
explosion, and consequent loss of the airplane.

Comments

We gave the public the opportunity to participate in developing
this AD. The following presents the comments received on the proposal
(78 FR 75512, December 12, 2013) and the FAA's response to each
comment.

Requests To Remove Certain Language in ``Relevant Service Information''
Section

Boeing, All Nippon Airways (ANA), and American Airlines (AA) asked
that the third sentence in the ``Relevant Service Information'' section
of the NPRM (78 FR 75512, December 12, 2013) be removed. That sentence
specified ``The related investigative actions include an eddy current
inspection of the wing front spar for cracking and a detailed
inspection of the bolt forward of the wing front spar upper chord for
cracking or missing bolts.'' Boeing stated that those actions seem
unrelated to the intent of the AD. ANA stated that the eddy current
inspection is not specified in Boeing Special Attention Service
Bulletin 737-28-1312, dated April 19, 2013. AA stated that those
actions are not included in the referenced service information, and
asked that those actions be clarified or that the ``Relevant Service
Information'' section be corrected by removing those actions.
We agree that the ``Relevant Service Information'' section in the
NPRM (78 FR 75512, December 12, 2013) should not have stated that the
related investigative actions include an eddy current inspection of the
wing front spar for cracking; that inspection is not related to the
unsafe condition addressed by this AD. However, the ``Relevant Service
Information'' section of the NPRM is not carried over into this final
rule; therefore, no change to this final rule is necessary in this
regard.

Request To Include Equivalent Parts

AA asked that we add ``equivalent fully cushioned wire clamps'' to
the approved part numbers (P/Ns) identified in paragraph (h) of the
proposed AD (78 FR 75512, December 12, 2013) (redesignated as paragraph
(i) of this AD). AA stated that paragraph (h) of the proposed AD
prohibits the installation of a wire support clamp within the ECS bay
area, unless the clamp has P/N TA0930034-10, TA0930034-10P, TA0930034-
11, or TA0930034-12P. AA noted that adding ``equivalent fully cushioned
wire clamps'' would account for future part number changes and future
availability issues of the included part numbers. AA also asserted that
including the equivalent clamps also would reduce the potential for
airplanes becoming noncompliant during future maintenance.
We do not agree to add ``equivalent fully cushioned wire clamps''
to the approved part numbers identified in paragraph (i) of this AD
(designated as paragraph (h) of the proposed AD). AA did not submit any
data to show how equivalency of the wire support clamp is to be
established, maintained, and controlled. However, under the provisions
of paragraph (j) of this AD, we may consider requests to use alternate
clamps if sufficient data are submitted to substantiate that these
clamps meet the standards for the environmental (temperature,
vibration, fluid resistance) and performance requirements necessary to
provide an acceptable level of safety. We have not changed this final
rule in this regard.

Request To Change Costs of Compliance Section

AA asked that we change the inspection estimate in the ``Costs of
Compliance'' section in the NPRM (78 FR 75512, December 12, 2013) from
6 to 24 work-hours, as specified in Boeing Special Attention Service
Bulletin 737-28-1312, dated April 19, 2013.
We agree to change the work-hour estimate for the inspection
specified in the ``Costs of Compliance'' section. After further review
of Boeing Special Attention Service Bulletin 737-28-1312, dated April
19, 2013, we have determined that the work-hour estimate of 24 hours is
based on correct installation of the wire clamps and does not include
repairs to the wiring. Therefore, we have increased the work hour
estimate for the inspection specified in the ``Costs of Compliance''
section of this final rule.

Changes to This Final Rule

Since we issued the NPRM (78 FR 75512, December 12, 2013), Boeing
has issued Special Attention Service Bulletin 737-28-1312, Revision 1,
dated April 21, 2014. No additional work is necessary on airplanes that
were changed using Boeing Special Attention Service Bulletin 737-28-
1312, dated April 19, 2013. We have added Boeing Special Attention
Service Bulletin 737-28-1312, Revision 1, dated April 21, 2014, to
paragraphs (c) and (g) of this AD, and added a new credit paragraph (h)
to this AD giving credit for Boeing Special Attention Service Bulletin
737-28-1312, dated April 19, 2013.
Since we issued the NPRM (78 FR 75512, December 12, 2013), we have
determined that the language used in the ``Parts Installation
Limitations'' paragraph of the AD needs clarification. As written, the
language could be interpreted as applying to ``all'' clamps located in
the ECS bay area; however, the limitation only applies to certain
clamps. We have changed paragraph (h) of the the proposed AD
(redesignated as paragraph (i) of this AD) to provide that
clarification.

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 changes described previously. We also determined that
these changes will not increase the economic burden on any operator or
increase the scope of this AD.

Costs of Compliance

We estimate that this AD affects 519 airplanes of U.S. registry.
We estimate the following costs to comply with this AD:

Estimated Costs

We estimate the following costs to do any necessary related
investigative and corrective actions that would be required based on
the results of the inspection. We have no way of determining the number
of aircraft that might need these actions.

On-Condition Costs

We have received no definitive data that would enable us to provide
cost estimates for the on-condition repair of chafed or damaged wiring
specified in this AD.
According to the manufacturer, some of the costs of this 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 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.

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 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.

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):