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Federal Register / Vol. 86, No. 170 / Tuesday, September 7, 2021 / Rules and Regulations
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S.A. Safran Helicopter Engines Arrius 2B1, 2B1A, 2B2, and 2K1 model turboshaft engines. AD 20140406
required initial and repetitive inspections of the hydro-mechanical metering unit HMU high-pressure pump drive gear shaft splines, cleaning and inspections of the sleeve assembly splines, and replacement of the sleeve assembly on the affected high-pressure pump drive gear shaft or replacement of the HMU if the HMU fails inspection.
This AD was prompted by in-flight shutdowns caused by interrupted fuel supply at the HMU. This AD requires revised inspections and continues to require cleaning of the sleeve assembly splines, and replacement of the sleeve assembly on the affected high-pressure pump drive gear shaft or replacement of the HMU if the HMU fails an inspection.
The FAA is issuing this AD to address the unsafe condition on these products.
DATES: This AD is effective October 12, 2021.
The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD
as of October 12, 2021.
ADDRESSES: For service information identified in this final rule, contact Safran Helicopter Engines, S.A., Avenue du 1er Mai, 40220 Tarnos, France;
phone: +33 0 5 59 74 45 11. You may view this service information at the FAA, Airworthiness Products Section, Operational Safety 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 at https
www.regulations.gov by searching for and locating Docket No. FAA2021
0137.
Examining the AD Docket You may examine the AD docket at https www.regulations.gov by searching for and locating Docket No.
FAA20210137; 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 mandatory continuing airworthiness information MCAI, any comments received, and other information. The address for Docket Operations is U.S. Department of Transportation, Docket Operations, M30, West Building Ground Floor, Room W12140, 1200 New Jersey Avenue SE, Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT:
Wego Wang, Aviation Safety Engineer, ECO Branch, FAA, 1200 District Avenue, Burlington, MA 01803; phone:
781 2387134; fax: 781 2387199;
email: wego.wang@faa.gov.

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SUPPLEMENTARY INFORMATION:

Background The FAA issued a notice of proposed rulemaking NPRM to amend 14 CFR
part 39 to supersede AD 20140406, Amendment 3917764 79 FR 9990, February 24, 2014, AD 20140406.
AD 20140406 applied to all Turbomeca S.A. Arrius 2B1, 2B1A, 2B2, and 2K1 model turboshaft engines. The NPRM published in the Federal Register on March 12, 2021 86 FR
14017. The NPRM was prompted by inflight shutdowns caused by interrupted fuel supply at the HMU. Since the FAA
issued AD 20140406, the manufacturer has published new service information that revises the inspections for certain HMUs, reduces compliance times for initial inspections, and allows application of non-cumulative tolerance of 10% of operating hours to be applied to the timing of the repetitive inspection of HMUs installed on certain engines. In the NPRM, the FAA proposed to continue to require cleaning of the sleeve assembly splines and replacing the HMU or the sleeve assembly on the affected high-pressure pump drive gear shaft if the HMU fails inspection. In the NPRM, the FAA also proposed to require initial and repetitive inspections of the HMU high-pressure pump drive gear shaft splines. The FAA is issuing this AD to address the unsafe condition on these products.
The European Union Aviation Safety Agency EASA, which is the Technical Agent for the Member States of the European Community, has issued EASA
AD 20200033, dated February 25, 2020
referred to after this as the MCAI, to address the unsafe condition on these products. The MCAI states:
A number of in-flight shut-down IFSD
occurrences have been reported for ARRIUS
2 engines. The results of the technical investigations concluded that these events were caused by deterioration of the splines on the high pressure HP/low pressure LP
pump assembly drive shaft of the HMU, which eventually interrupted the fuel supply to the engine.
This condition, if not detected and corrected, could lead to further cases of engine IFSD, possibly resulting in forced landing with consequent damage to the helicopter and injury to occupants.
To address these occurrences, Turbomeca published MSB 319 73 2825 up to version G to provide instructions for inspection of the HMU and sleeve assembly. Consequently, EASA issued AD 20130082 to require repetitive inspections of the drive gear shaft splines of the HP pump, and, depending on findings, accomplishment of applicable corrective actions.
Since that EASA AD was issued, SAFRAN published the MSB to provide specific inspection instructions for HMU

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installed on a helicopter after 31 January 2013, to reduce the compliance time for the initial inspection of Group 1 engines that were not previously inspected in accordance with version G or later of the MSB, and to provide some operational margin before the first inspection in all possible scenarios.
For the reason described above, this EASA AD retains the requirements of AD
20130082, which is superseded, and requires accomplishment of the actions in accordance with the instructions of the MSB, as defined in this EASA AD.

You may obtain further information by examining the MCAI in the AD
docket at https www.regulations.gov by searching for and locating Docket No.
FAA20210137.
FAAs Determination This product has been approved by EASA and is approved for operation in the United States. Pursuant to the FAAs bilateral agreement with the European Community, EASA has notified the agency of the unsafe condition described in the MCAI and service information. The FAA is issuing this final rule because the agency evaluated all the relevant information provided by EASA and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.
Discussion of Final Airworthiness Directive Comments The FAA received no comments on the NPRM or on the determination of the costs.
Conclusion The FAA reviewed the relevant data and determined that air safety requires adoption of the AD as proposed.
Accordingly, the FAA is issuing this AD
to address the unsafe condition on these products. This AD is adopted as proposed in the NPRM.
Related Service Information Under 1
CFR Part 51
The FAA reviewed Safran Helicopter Engines Mandatory Service Bulletin MSB No. 319 73 2825, Version J, dated March 15, 2019. This MSB specifies procedures for inspecting the HMU
high-pressure pump drive gear shaft splines and cleaning and inspecting the sleeve assembly splines. 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 ADDRESSES.
Per Safran Helicopter Engines standing practice at the time MSB 319
73 2825, Version J, was issued, MSB 319
73 2825, Version J, is undated. The issue
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