DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-1118; Product Identifier 2017-NE-40-AD; Amendment
39-19313; AD 2018-13-01]
RIN 2120-AA64

Airworthiness Directives; Rolls-Royce Corporation Turboshaft
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
Rolls-Royce Corporation (RRC) model 250-C turboshaft engines. This AD
was prompted by several reports of engine power loss, one of which
resulted in a fatal helicopter accident. This AD requires removal of
the power turbine governor (PTG) bearing assembly, part number (P/N)
2544198, and its replacement with a bearing assembly eligible for
installation. We are issuing this AD to address the unsafe condition on
these products.

DATES: This AD is effective August 16, 2018.

ADDRESSES: For service information identified in this final rule,
contact Rolls-Royce Corporation, 450 South Meridian Street, Mail Code
NB-02-05, Indianapolis, IN 46225; phone: 317-230-3774; email:
indy.pubs.services@rolls-royce.com; internet: www.rolls-royce.com.
You may view this service information at the FAA, Engine and Propeller
Standards Branch, 1200 District Avenue, Burlington, MA. 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-2018-1118.

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-
1118; 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 Docket 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: John Tallarovic, Aerospace Engineer,
Chicago ACO Branch, FAA, 2300 E. Devon Ave., Des Plaines, IL 60018;
phone: 847-294-8180; fax: 847-294-7834; email:
john.m.tallarovic@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 Rolls-Royce
Corporation (RRC) model 250-C turboshaft engines. The NPRM published in
the Federal Register on February 1, 2018 (83 FR 4609). The NPRM was
prompted by several reports of loss of engine power on certain RRC
model 250-C turboshaft engines installed on single-engine helicopters.
One of these instances of power loss resulted in a fatal helicopter
accident on May 4, 2016. The NPRM proposed to require removal of the
affected PTG bearing assembly and replace it with a bearing assembly
with a new design. 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 Specify the New Bearing Assembly

The NTSB and Honeywell Aerospace requested that the AD prohibit the
installation of bearing assembly, P/N 2544198, and specify the
installation of the new bearing assembly, P/N 2526146. The NTSB
expressed concern that differences between the proposed AD and the
actions described in the Honeywell SB and Rolls-Royce CEBs could lead
to the reinstallation of a dual-spool bearing into an affected PTG.
We partially agree. We agree with the request to prohibit the
installation of another bearing assembly, P/N 2544198, because our
intent is to remove them from service. We disagree with the request to
specify the installation of the new bearing assembly, P/N 2526146,
because of the possibility of a new bearing P/N being introduced or the
specified P/N being discontinued in the future. We added an
installation prohibition paragraph to this AD to prohibit the
installation of bearing assembly, P/N 2544198.

Request To Re-Identify the PTG After Changing the Bearing Assembly

The NTSB and Honeywell Aerospace requested that the AD require re-
identifying the PTG P/N after changing the bearing assembly in
accordance with the related service information. Honeywell Aerospace
reasoned that maintenance personnel and operators could easily
determine if the service bulletin has been accomplished. This increases
the efficiency of operations and reduces the potential for
misunderstandings about whether the bearing assembly has been replaced.
We disagree. While re-identifying the PTG after changing the
bearing assembly is helpful for maintenance personnel, we are not
requiring this action within this AD. During the replacement of the
bearing assembly, P/N 2544198, the related service information
instructs personnel to re-identify the PTG. We did not change this AD.

Request To Reduce the Compliance Time

Honeywell Aerospace requested that we reduce the compliance time to
50 hours or within 90 days for PTGs that have greater than 750 hours.
The commenter reasoned that the original compliance schedule was
established 10 years ago based on field experience at that time. The
fatal accident referenced in the NPRM occurred on a PTG with 1,048.7
hours since new.
We disagree. The compliance time for removing the bearing assembly,
P/N 2544198, in this AD is based on Rolls-
Royce Corporation Commercial Engine Bulletin (CEB) 1402, Revision 2,
dated February 4, 2009. The failure history shows that the number of
bearing assembly failures fell sharply following the initial
publication of RRC CEB 1402 in 2008. The replacement strategy has
proven successful. As a result, we believe that the majority of the
fleet has replaced the bearing assembly, P/N 2544198, and only a few
remain in service. Besides the fatal accident, there have not been any
other bearing failures noted between 2012 and 2018. We, therefore, find
it unnecessary to reduce the compliance time as noted by the commenter.
We did not change this AD.

Request To Increase the Number of Affected Engines

Honeywell Aerospace noted that only 1,200 engines installed on
airplanes of U.S. registry may be affected, compared with the 2,928
mentioned in the NPRM, based on a review of modification records
provided to Honeywell by repair stations.
We disagree. We are estimating the total number of engines affected
by this AD based on the data available to us. We did not change this
AD.

Request To Clarify the Affected Engines

An individual commenter requested that we clarify that only those
engine models that have bearing assembly, P/N 2544198, installed are
affected.
We agree. We have updated paragraph (c) of this AD to clarify that
engines with bearing assembly, P/N 2544198, installed are affected.

Request To Identify the Model, Brand, and P/N of the PTG

Aircraft Maintenance Netherlands requested that this AD identify
the model, brand, and P/N of the affected PTG that must be replaced.
The commenter reasoned that various PTG models can be installed on the
affected engines.
We disagree. This AD provides the overall engine model
applicability. The related service information provides specific
information regarding the PTGs, including the manufacturer, model, and
P/Ns. We did not change this AD.

Question on Not Issuing the AD Earlier

An individual commenter asked why an AD was not issued in 2009 when
RRC issued a statement regarding the failure of the bearing assembly.
The FAA uses a risk-based approach to make continued operational
safety decisions. When RRC issued CEB 1402, Revision 2, in 2009, our
evaluation of the fleet risk did not support an AD. We update our fleet
risk evaluation periodically as new information becomes available and
have now determined that an AD is justified. We did not change this AD.

Question if Replacement Part Verification Testing Was Completed

An individual commenter asked if tests or procedures were completed
to verify that the replacement bearing assembly resolves the failure of
bearing assembly, P/N 2544198, due to the lack of lubrication.
We note that replacement parts, such as this replacement bearing
assembly, undergo design analysis and testing before being approved for
use by the FAA. No change is requested. We did not change this AD.

Request for Clarification on the Number of Affected Engines

An individual commenter noted that the NPRM estimates that 2,928
model 250-C turboshaft engines are affected, however, the RRC website
estimates that there are an estimated 16,000 model 250-C engines
currently in service.
This AD applies to all RRC model 250-C turboshaft engines that
could have the bearing assembly, P/N 2544198, installed. Many of those
engines have already had the bearing assembly, P/N 2544198, replaced
when new parts became available. Based on the available data, we
estimate that 2,928 engines may still have the bearing assembly, P/N
2544198, installed. We did not change this AD.

Question on the Availability of a Replacement Bearing Assembly

An individual commenter asked if RRC still needs to design a new
bearing assembly or if a replacement bearing assembly is already
available.
A replacement bearing assembly, P/N 2526146, is available for
installation. We did not change this AD.

Support for the AD

An individual commenter expressed support for the NPRM as written.

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. We have
determined that these minor changes:
[Agr]re consistent with the intent that was proposed in
the NPRM for addressing 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

We reviewed Rolls-Royce Corporation Commercial Engine Bulletin
(CEB) 1402, Revision 2, dated February 4, 2009. The CEB provides
guidance on replacing the PTG bearing assembly, P/N 2544198, with a
bearing assembly eligible for installation.

Costs of Compliance

We estimate that this AD affects 2,928 engines installed on
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.
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):