Discussion
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2015-20-04, Amendment 39-18282 (80 FR 61717, October 14, 2015), (``AD 2015-20-04''). AD 2015-20-04 applied to certain P&WC PT6B-37A turboshaft engines. The NPRM published in the Federal Register on September 17, 2018 (83 FR
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46898). The NPRM was prompted by reports of incorrect engine torque for PT6B-37A turboshaft engines. The NPRM proposed to require removal from service and replacement of the No. 9 and No. 10 position bearings. The FAA is issuing this AD to address the unsafe condition on these products.
Transport Canada Civil Aviation, which is the aviation authority for Canada, has issued Transport Canada AD CF-2015-01R1, dated November 18, 2016 (referred to after this as ``the MCAI''), to address the unsafe condition on these products. The MCAI states:
Five incidents of incorrect engine torque indication have been reported for PT6B-37A engine installations on AW119MKII helicopters. A lower than actual engine torque indication due to a faulty indication system, particularly on a helicopter being operated at max allowable torque (90 to 110%) range, may result in undetected over-torque condition.
Repeat undetected over-torque conditions that are not corrected in accordance with conditional inspection requirements of original equipment manufacturer (OEM) Instructions for Continued Airworthiness (ICAs), may have a negative impact on the operational life of aircraft components. Investigation by P&WC has determined the root cause of the subject torque indication anomaly to be an axial migration of the #9 and #10 bearings at the engine torque sensing gear location.
P&WC has introduced a new bearing configuration through its SB No. PT6B-72-39108, Revision No. 1, dated September 5, 2017, that effectively addresses the axial movement issue at No. 9 and No. 10 bearing positions. You may obtain further information by examining the MCAI in the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2018-0739.
Comments
The FAA 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.
Support for the AD
An individual commenter expressed support for the NPRM as written.
Miscellaneous Comments
An individual commenter provided comments not relevant to this AD. The FAA did not change this AD.
Update to the Service Information
The FAA determined the need to incorporate the latest service information in this AD. The FAA revised the reference to P&WC SB No. PT6B-72-39108 in the paragraph (g) of this AD from the original issue, dated September 30, 2016, to Revision No. 1, dated September 5, 2017.
The FAA also updated the reference in paragraph (g) of this AD to P&WC SB No. PT6B-72-39092 from Revision No. 4, dated December 29, 2014, to Revision No. 5, dated October 27, 2017.
Addition of Credit for Previous Action
The FAA determined the need to add a Credit for Previous Action section to allow credit for previous replacement of the No. 9 and No 10 position bearings if accomplished using P&WC SB No. PT6B-72-39108, dated September 30, 2016.
Conclusion
The FAA reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting this AD as proposed except for minor editorial changes. The FAA has determined that these minor changes:
Are 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.
Related Service Information Under 1 CFR Part 51
The FAA reviewed P&WC SB No. PT6B-72-39108, Revision No. 1, dated September 5, 2017. The SB describes procedures for replacing affected bearings. 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
The FAA reviewed P&WC SB No. PT6B-72-39092, Revision No. 5, dated October 27, 2017. The service information describes procedures for removing affected bearings.
Costs of Compliance
The FAA estimates that this AD affects 119 engines installed on helicopters of U.S. registry.
The FAA estimates the following costs to comply with this AD:
Estimated Costs ----------------------------------------------------------------------------------------------------------------
Cost per Cost on U.S.
Action Labor cost Parts cost product operators ---------------------------------------------------------------------------------------------------------------- Remove and replace No. 9 and No. 10 65 work-hours x $85 per $37,874 $43,399 $5,164,481
bearings. hour = $5,525. ----------------------------------------------------------------------------------------------------------------
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.
The FAA is 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 iswithin 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
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responsibilities amongthe 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) Will not affect intrastate aviation in Alaska, and
(3) 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.