DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-9450; Product Identifier 2016-NE-25-AD]
RIN 2120-AA64

Airworthiness Directives; Honeywell International Inc. Turboprop
and Turboshaft Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for
certain Honeywell International Inc. TPE331 turboprop and TSE331
turboshaft engines. This proposed AD was prompted by recent reports of
failures of the direct drive fuel control gears and bearings in the
hydraulic torque sensor gear assembly, part number (P/N) 3101726-3.
This proposed AD would require initial and repetitive engine oil filter
sampling and analysis of the affected engines. This proposed AD would
also require inspection of hydraulic torque sensor gear assemblies that
do not meet oil filter inspection requirements. This proposed AD would
further require improved component overhaul procedures that would
remove from service, by attrition, certain P/N hydraulic torque sensor
gear assemblies. We are proposing this AD to correct the unsafe
condition on these products.

DATES: We must receive comments on this proposed AD by October 30, 2017.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:

Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the
instructions for submitting comments.

Fax: 202-493-2251.

Mail: U.S. Department of Transportation, Docket Operations, M-30, West
Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE.,
Washington, DC 20590.

Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.

For service information identified in this NPRM, contact Honeywell
International Inc., 111 S 34th Street, Phoenix, AZ 85034-2802; phone:
800-601-3099; Internet: https://myaerospace.honeywell.com/wps/portal.
You may view this service information at the FAA, Engine and Propeller
Standards Branch, Policy and Innovation Division, 1200 District Avenue,
Burlington, MA. For information on the availability of this material at
the FAA, call 781-238-7125.

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-2016-9450;
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 proposed AD, the regulatory evaluation, any comments
received, and other information. The street address for the Docket
Office (phone: 800-647-5527) is in the ADDRESSES section. Comments will
be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Joseph Costa, Aerospace Engineer, FAA,
Los Angeles ACO Branch, Compliance and Airworthiness Division, 3960
Paramount Blvd., Lakewood, CA 90712-4137; phone: 562-627-5246; fax:
562-627-5210; email: joseph.costa@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or
arguments about this NPRM. Send your comments to an address listed
under the ADDRESSES section. Include "Docket No. FAA-2016-9450;
Directorate Identifier 2016-NE-25-AD" at the beginning of your
comments. We specifically invite comments on the overall regulatory,
economic, environmental, and energy aspects of this NPRM. We will
consider all comments received by the closing date and may amend this
NPRM because of those comments.

We will post all comments we receive, without change, to http://www.
regulations.gov, including any personal information you provide. We
will also post a report summarizing each substantive verbal contact we
receive about this NPRM.

Discussion

We received reports of failures of the direct drive fuel control
gears and bearings in the hydraulic torque sensor gear assembly, P/N
3101726-3. These failures are similar to previous failures in hydraulic
torque sensor gear assemblies, P/Ns 3101726-1 and 3101726-2, that
resulted in in-flight shutdowns and accidents in single and twin-engine
airplanes.

After recent failures of the hydraulic torque sensor gear assembly,
P/N 3101726-3, installed in six engines, we re-performed oil filter
analyses on samples taken prior to these failures. We found the wear
metals, including, but not limited to, M50 steel platelets, in the
engine oil filter samples. The FAA has found that the oil filter
analysis for wear metals provides an effective means of identifying
premature wear of the components in the hydraulic torque sensor gear
assembly.

This proposed AD would require initial and repetitive oil filter
analysis for wear metals from the hydraulic torque sensor gear
assembly. This AD also requires the use of later revisions of the
hydraulic torque sensor gear assembly component overhaul manuals that
provide improved maintenance instructions and removes from service, by
attrition, hydraulic torque sensor gear assemblies, P/N 3101726-1 and
certain P/N 3101726-2 of a pre-Series 9 configuration. This condition,
if not corrected, could result in failure of the hydraulic torque
sensor gear assembly, in-flight shutdown, and reduced control of the
airplane.

Related Service Information Under 1 CFR Part 51

Honeywell has issued Honeywell Service Information Letter (SIL)
P331-97, Revision 11, dated July 23, 2008. The SIL describes procedures
for conducting the spectrometric oil and filter analysis program to
sample and analyze metal particles in the engine lubricating system.
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 Service Information

We reviewed the improved procedures and limitations in the
Honeywell Torque Sensor Gear Assembly Overhaul Manual with Illustrated
Parts List, 72-00-17, Revision 10, dated October 31, 2013, for the
TPE331 and TSE331 torque sensor gear assemblies. We also reviewed
Honeywell's TPE331 Line Maintenance Training Manual which provides
guidance for obtaining oil filter samples. In addition, we reviewed
Honeywell Service Bulletins (SBs) TPE331-72-0402, Revision 6, dated
November 26, 1997; TPE331-72-0403, Revision 5, dated January 20, 1989;
TPE331-72-0404, Revision 8, dated September 13, 2016; TPE331-72-0823,
Revision 3, dated September 13, 1996; TSE331-72-5003, Revision 3, dated
January 20, 1989; and TPE331-72-0180, Revision 36, dated April 7, 2016.
The SBs address the inspection intervals for the oil and filter
analysis for the affected TPE331 and TSE331 engines.

FAA's Determination

We are proposing this AD because we evaluated all the relevant
information and determined the unsafe condition described previously is
likely to exist or develop in other products of the same type design.

Proposed AD Requirements

This proposed AD requires initial and repetitive engine oil filter
analysis of the affected TPE331 and TSE331 engines. This proposed AD
also requires inspection of affected hydraulic torque sensor gear
assemblies, and replacement or overhaul of those torque sensor gear
assemblies that do not meet inspection requirements. This proposed AD
restricts the use of earlier versions of the hydraulic sensor gear
component overhaul manual.

Differences Between This Proposed AD and the Service Information

Honeywell service information does not recommend oil filter
sampling and analysis and hydraulic torque sensor gear assembly
inspection within specified times for applicable engines. Because of
recent failures, this proposed AD defines specific time requirements
for performing engine oil filter sampling and analysis for all
applicable TPE331 and TSE331 engines and, if necessary, hydraulic
torque sensor gear assembly inspections. This proposed AD would require
the oil filter sample analysis, which is only part of Honeywell's
recommended spectrometric oil and oil filter analysis program.

Costs of Compliance

We estimate that this proposed AD affects 3,831 engines installed
on airplanes of U.S. registry. We estimate the following costs to
comply with this proposed AD:

We estimate that 3,831 engines will require a records review to
determine if they have an affected hydraulic torque sensor gear
assembly installed.

Estimated Costs

We estimate that 2,542 engines operating under Parts 121 or 135 and
544 engines operating under Part 91 will be required to perform oil
filter sampling and analysis.

Estimated Costs

We estimate that 242 engines will require that the hydraulic torque sensor
gear assembly be overhauled during the first year of inspection.

Estimated Overhaul Costs

We estimate that 217 engines will require hydraulic torque sensor
gear assembly inspection after an unacceptable oil filter analysis
during the first year of inspection.

On-Condition 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.

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
appliances to the Manager, Engine and Propeller Standards Branch,
Policy and Innovation Division.

Regulatory Findings

We determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would 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 this proposed
regulation:

(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 to the extent
that it justifies making a regulatory distinction, 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.

The Proposed Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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):