DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2018-0216; Product Identifier 1988-ANE-18-AD; Amendment
39-19474; AD 2018-22-01]
RIN 2120-AA64

Airworthiness Directives; Honeywell International Inc. Turboprop
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are superseding Airworthiness Directive (AD) 88-12-10 for
certain Honeywell International Inc. (Honeywell) TPE331 turboprop
engines. AD 88-12-10 required reducing the life limit for certain
second stage turbine rotors. This AD requires removing certain second
stage turbine rotors from service at a reduced life limit. This AD was
prompted by report that a TPE331-11U engine experienced an uncontained
rotor separation. In addition, cracks were discovered through eddy
current inspection (ECI) in the bore of the second stage turbine rotor
assembly after publication of AD 88-12-10. We are issuing this AD to
address the unsafe condition on these products.

DATES: This AD is effective December 10, 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.
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-2018-0216.

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-2018-
0216; 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 to supersede AD 88-12-10, Amendment 39-5910 (53 FR 19766, May
31, 1988), (``AD 88-12-10''). AD 88-12-10 applied to Honeywell TPE331-
10, -10R, -10U, -10UA, -10UF, -10UG, -10UGR, -10UR, and -11U turboprop
engines equipped with 2nd stage turbine rotors, part numbers 3102106-1,
-6, and -8, installed. The NPRM published in the Federal Register on
June 20, 2018 (83 FR 28550). The NPRM was prompted by a report that a
TPE331-11U engine installed on an M7 Aerospace LP SA227 airplane
experienced an uncontained rotor separation. In addition, cracks were
discovered through ECI in the bore of the second stage turbine rotor
assembly after publication of AD 88-12-10. The NPRM proposed to remove
certain second stage turbine rotors from service at a reduced life
limit. 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 AD. The following presents the comments received on the NPRM and
the FAA's response to each comment.

Request To Revise Compliance Times

Honeywell requested that we remove from the NPRM the statement that
the FAA finds that allowing an additional 100 cycles-in-service before
their removal provides a sufficient level of safety for applicable
second stage turbine rotors that have been in service for 30 years
after the publication of AD 88-12-10. Honeywell indicated it believes
that most of the IN100 rotors have been replaced at around 3,500 cycles
during hot section inspection. Honeywell noted that the rotors would
not make it to the next hot section inspection with a life of 4,800
cycles. Honeywell noted that there is a not a lot of field experience
for IN100 rotors beyond 3,500 cycles.
Honeywell commented that the removal schedule in the Honeywell
service bulletin needs to remain the same (within 100 cycles-in-service
for 3,301 to 4,000 cycles since new (CSN) rotors and within 50 cycles-
in-service for 4,001 to 4,800 CSN rotors) since the event rotor failed
at around 4,100 cycles. Additionally, Honeywell has also found rotors
through eddy current inspection that had long cracks at around 4,300
cycles.
We disagree. We would normally only require removal of parts within
50 cycles-in-service after the effective date of an AD when the risk
justifies immediate action. The FAA assessed the risk of the affected
rotors based on service experience and IN100 rotor propagation life of
cracked and failed rotors. We found that the additional cycles in
service allowed by this AD before the removal of the second stage
turbine rotors provides an acceptable level of safety. We did not
change this AD.

Conclusion

We reviewed the relevant data, considered the comment received, and
determined that air safety and the public interest require adopting
this AD as proposed.

Related Service Information

We reviewed Honeywell Service Bulletin (SB) TPE331-72-A2319,
Revision 0, dated April 25, 2018, and TPE331-72-A2310, Revision 0,
dated January 26, 2018. These SBs describe procedures for replacement
of the second stage turbine rotor assembly installed on TPE331-8, -10,
-10N, -10R, -10U, -10UA, -10UF, -10UG, -10UGR, -10UR, and -11U model
engines.

Costs of Compliance

We estimate that this AD affects 100 engines installed on airplanes
of U.S. registry.
We estimate that 20 commercial engines and 80 general aviation
engines will need this turbine rotor replacement 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.
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

We have determined that 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 removing Airworthiness Directive (AD)
88-12-10, Amendment 39-5910 (53 FR 19766, May 31, 1988), and adding the
following new AD: