DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0020; Product Identifier 2016-NE-33-AD; Amendment
39-19209; AD 2018-04-13]
RIN 2120-AA64

Airworthiness Directives; Honeywell International Inc. Turbofan Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain
Honeywell International Inc. AS907 series turbofan engines. This AD was
prompted by seven loss-of-thrust-control events attributed to water
intrusion of the engine electronic control unit (ECU). This AD requires
applying sealant to identified areas of the ECU and requires inserting
a copy of certain airplane operating procedures into the applicable
flight manuals. We are issuing this AD to address the unsafe condition
on these products.

DATES: This AD is effective April 12, 2018.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of April 12,
2018.

ADDRESSES: For service information identified in this final rule,
contact Honeywell International Inc., 111 S 34th Street, Phoenix, AZ
85034-2802; phone: 800-601-3099; internet: https://myaerospace.honeywell.com/wps/portal/!ut/. You may view this service
information at the FAA, Engine and Propeller Standards Branch, 1200
District Avenue, Burlington, MA 01803. For information on the
availability of this material at the FAA, call 781-238-7759. It is also
available on the internet at http://www.regulations.gov by searching
for and locating Docket No. FAA-2017-0020.

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-2017-
0020; 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 (phone: 800-647-
5527) is Document Operations, 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: Joseph Costa, Aerospace Engineer, Los
Angeles ACO Branch, FAA, 3960 Paramount Blvd., Lakewood, CA 90712-4137;
phone: 562-627-5246; fax: 562-627-5210; email: joseph.costa@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 Honeywell
International Inc. AS907 series turbofan engines. The NPRM published in
the Federal Register on August 2, 2017 (82 FR 35914). The NPRM was
prompted by seven loss-of-thrust-control events attributed to water
intrusion of the engine ECU with one event having two in-flight
shutdowns (IFSDs) during the same flight. All loss-of-thrust-control
events occurred with engines within three years in service. The NPRM
proposed to require applying sealant to identified areas of the ECU and
to require inserting a copy of certain airplane operating procedures
into the applicable flight manuals. We are issuing this AD to address
the unsafe condition on these products.

Comments

We 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.

Request To Change Differences Between This Proposed AD and the Service
Information

Honeywell requested changing the recommended compliance time stated
in the ``Differences Between This Proposed AD and the Service
Information'' paragraph. Honeywell stated the compliance time started
with the issuance of its initial Service Bulletin (SB) AS907-76-9021,
Revision 0, dated May 13, 2016.
We partially agree. We agree it would have been appropriate to
reference the correct compliance time in this discussion within the
NPRM. We do not agree to revise this final rule because this discussion
does not exist in the final rule. Further explanation in this final
rule is not necessary. We did not change this AD.

Request To Remove Interim Action

Honeywell requested that we remove interim action from this AD.
Honeywell reasoned that the redesigned ECU, which is equivalent to an
ECU sealed with external sealant, is outside the scope of this AD.
We agree since Honeywell does not plan to retrofit or repair older
ECUs. The older ECUs will be sealed with external sealant for the life
of the ECU. We removed the Interim Action paragraph from this AD.

Request To Revise Number of Affected Engines

Honeywell requested that the number of engines affected be changed.
Honeywell stated the current number of affected engines worldwide is
680 engines installed in airplanes.
We partially agree. We agree with Honeywell's current accounting of
680 affected engines worldwide. We disagree with changing the number of
affected engines in this AD because our requirement is to estimate the
number of engines installed on U.S. airplanes. Therefore, we are
maintaining the estimate made in the NPRM that 477 engines are
installed on airplanes in the U.S. Registry.

Request To Clarify Applicability

Honeywell requested that we remove references to ECU Mod Record
numbers from this AD. Honeywell reasoned that the affected ECUs Mod
Record numbers are only advanced for production sealed ECUs; therefore,
ECU Mod Record numbers are not a consistent indication of ECU sealing
service bulletin compliance.
We agree. Mod Record numbers are not a good indicator of ECU
sealing. We revised the applicability of this AD to refer to the engine
model, serial numbers, and listed ECU part numbers (P/Ns) that are not
sealed in the areas identified in Figures 1 through 13 of Honeywell SB
AS907-76-9021, Revision 1, dated April 20, 2017. This change revises
the method for operators to determine applicability but does not expand
the scope of this AD since the affected populations of ECUs are the
same in this final rule as in the NPRM.

Request To Change the Unsafe Condition

Honeywell requested we revise the unsafe condition statement with
updated field event information.
We agree because the unsafe condition in paragraph (e) of the NPRM
did not include four prior similar loss-of-thrust-control field events
noted in the Discussion section. We changed the unsafe condition
paragraph to refer to seven low-time loss-of-thrust control events
attributed to water intrusion of the engine ECU.

Request To Add Inspection for Application of Sealant

Honeywell requested that we revise the compliance section of this
AD by requiring that applicable ECU P/Ns be inspected for application
of sealant. The requested change would clarify the method of
determining whether ECU sealing had been complied with.
We partially agree. As noted in our response, we have clarified the
Applicability section of this AD to refer only to affected ECUs that
are not sealed in the areas identified in Figures 1 through 13 of
Honeywell SB AS907-76-9021, Revision 1, dated April 20, 2017. We
therefore, do not need to add an inspection for the application of
sealant to the compliance section of this AD.

Request To Eliminate Re-Application of ECU Sealant

Honeywell requested that we remove references to re-application of
ECU sealant from this final rule. Honeywell commented that this step
will be accomplished through its continued airworthiness documents.
We agree that normal maintenance instructions make it unnecessary
to re-apply the ECU sealant. We revised this final rule by removing the
references to re-application of the ECU sealant.

Request To Change Compliance

NetJets questioned whether paragraphs (g)(4), (g)(5), and (g)(6)
were intended to be subparagraphs of paragraph (g)(3). They justified
the request by saying that the crew should only be alerted to Cyan
warning per the AFM (Airplane Flight Manual) Emergency Procedures.
We agree. We redesignated paragraphs (g)(4), (g)(5), and (g)(6) in
the NPRM as paragraphs (g)(2)(i), (g)(2)(ii), and (g)(2)(iii) in this
AD to clarify the intent of the Cyan warning.

Request To Change Credit for Previous Actions

NetJets requested that Honeywell SB AS907-76-9021, Revision 1,
dated April 20, 2017, be added to the Credit for Previous Actions
paragraph. They indicated that an AMOC (alternative method of
compliance) might be needed to take credit for this previous action if
Revision 1 of the SB was complied with prior to the effective date of
the AD.
We disagree because paragraph (f) already states that compliance is
necessary unless already done. We did not change this AD.

Revision to Installation Prohibition

We revised the Installation Prohibition, paragraph (h) of this AD,
to reflect changes to the applicability and to paragraph designations
discussed previously.

Miscellaneous Comments

An individual commenter asked who is responsible for the
enforcement of this final rule.
The FAA, Flight Standards Division, is responsible for enforcing
regulatory violations arising from noncompliance with ADs. We did not
change this AD.
An individual commenter suggested that the FAA is not taking into
account the costs associated with improving the standards of the
turbofan engines.
We have taken into account the costs associated with this
rulemaking as indicated within the Costs of Compliance section of the
NPRM. We did not change this AD.

Conclusion

We 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. We have determined that these minor changes:
[Agr]re 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 these changes will not increase the
economic burden on any operator or increase the scope of this final
rule.

Related Service Information Under 1 CFR Part 51

We reviewed Honeywell SB AS907-76-9021, Revision 1, dated April 20,
2017. The SB describes procedures for applying sealant to identified
areas of the ECU to prevent water from entering the ECU on AS907 series
engines. 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.

Other Related Information

We also reviewed Honeywell Operating Information Letter (OIL)
OIAS907-0001R00, dated March 14, 2017. The OIL provides instructions
for interrogating the onboard Maintenance Data Computer to clear engine
electronic fault conditions.

Costs of Compliance

We estimate that this ECU sealing affects 477 engines installed on
airplanes of U.S. registry.
We estimate the following costs to comply with this AD:

Estimated Costs

We estimate the following costs to do a visual inspection of the
ECUs. We estimate that 20 engines will need this inspection.

On-Condition Costs

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.
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 engines, propellers, and
associated appliances to the Manager, Engine and Propeller Standards
Branch, Policy and Innovation 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) 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):