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Federal Register / Vol. 86, No. 45 / Wednesday, March 10, 2021 / Rules and Regulations
report of a missing retaining ring of the inner race of the MRM upper bearing.
The actions of this AD are intended to address an unsafe condition on these products.
DATES: This AD is effective April 14, 2021.
The Director of the Federal Register approved the incorporation by reference of certain documents listed in this AD
as of April 14, 2021.
ADDRESSES: For service information identified in this final rule, contact Airbus Helicopters, 2701 N Forum Drive, Grand Prairie, TX 75052;
telephone 9726410000 or 800232
0323; fax 9726413775; or at https
www.airbus.com/helicopters/services/
technical-support.html. You may view the referenced service information at the FAA, Office of the Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N321, Fort Worth, TX
76177. It is also available on the internet at https www.regulations.gov by searching for and locating Docket No.
FAA20200847.
Examining the AD Docket You may examine the AD docket on the internet at https
www.regulations.gov by searching for and locating Docket No. FAA2020
0847; 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 AD, the European Aviation Safety Agency now European Union Aviation Safety Agency EASA AD, any service information that is incorporated by reference, any comments received, and other information. The street address for Docket Operations is U.S. Department of Transportation, Docket Operations, M
30, West Building Ground Floor, Room W12140, 1200 New Jersey Avenue SE, Washington, DC 20590.
FOR FURTHER INFORMATION CONTACT:
Scott Franke, Aviation Safety Engineer, General Aviation & Rotorcraft Section, International Validation Branch, FAA, 10101 Hillwood Pkwy., Fort Worth, TX
76177; telephone 8172225110; email scott.franke@faa.gov.
SUPPLEMENTARY INFORMATION:
Discussion The FAA issued a notice of proposed rulemaking NPRM to amend 14 CFR
part 39 by adding an AD that would apply to all Airbus Helicopters Model AS350B, AS350BA, AS350B1, AS350B2, AS350B3, and AS350D
helicopters; Model AS355E, AS355F, AS355F1, AS355F2, AS355N, and AS355NP helicopters; and Model EC130
B4 and EC130 T2 helicopters. The
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NPRM published in the Federal Register on September 21, 2020 85 FR
59217. The NPRM proposed to require a one-time inspection to verify the presence and correct installation of the MRM upper bearing retaining rings, a repetitive inspection of the sealant bead on the MRM for damage, and corrective actions if necessary. The proposed requirements were intended to detect, and correct if applicable, a missing retaining ring of the inner race of the MRM upper bearing. The FAA is issuing this AD to address this condition, which, if not detected and corrected, can lead to damage to the MRM and surrounding elements, possibly resulting in loss of control of the helicopter.
The NPRM was prompted by EASA
AD 20180206, dated September 20, 2018 EASA AD 20180206, issued by EASA, which is the Technical Agent for the Member States of the European Union, to correct an unsafe condition for certain Airbus Helicopters Model AS350B, AS350BA, AS350BB, AS350B1, AS350B2, AS350B3, and AS350D helicopters; Model AS355E, AS355F, AS355F1, AS355F2, AS355N, and AS355NP helicopters; and Model EC130 B4 and EC130 T2 helicopters.
Model AS355BB helicopters are not certificated by the FAA and are not included on the U.S. type certificate data sheet; this AD therefore does not include those helicopters in the applicability. EASA advises that during a scheduled inspection on an Airbus Helicopters Model AS350B3 helicopter, one of the two retaining rings of the inner race of the MRM upper bearing was found missing. These two retaining rings ensure that the inner race is correctly positioned with respect to the rollers, and, if one or both of these retaining rings are missing, it can lead to an unlimited shift of the inner race and compromise the function of the MRM upper bearing. This condition, if not detected and corrected, can lead to damage to the MRM and surrounding elements, possibly resulting in loss of control of the helicopter.
Airbus Helicopters developed an inspection to check that the upper and lower retaining rings of the inner race of the MRM upper bearing are present and correctly installed. EASA determined that the same condition may exist or develop on Airbus Helicopters Model AS350 helicopters, Model AS355
helicopters, and Model EC130
helicopters because they share a similar design and supply chain. Until the check of the upper and lower bearing retaining rings is accomplished, EASA
specifies that repetitive inspections of the MRM upper bearing sealant bead
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sealant bead should be accomplished to ensure the MRM remains serviceable.
EASA considers its AD an interim measure pending further investigation results, and notes that further AD action may follow.
Comments The FAA gave the public the opportunity to participate in developing this final rule. The FAA received 4
comments in support of the NPRM.
FAAs Determination These helicopters have been approved by EASA and are approved for operation in the United States. Pursuant to the FAAs bilateral agreement with the European Union, EASA has notified the FAA about the unsafe condition described in its AD. The FAA is issuing this AD after evaluating all of the information provided by EASA and determining the unsafe condition exists and is likely to exist or develop on other helicopters of the same type design and that air safety and the public interest require adopting the AD requirements as proposed.
Differences Between This AD and the EASA AD
Although EASA AD 20180206
specifies accomplishing the inspection of the installation of the MRM upper bearing inner race retaining rings within 660 hours time in service TIS or 24
months, whichever occurs first, the FAA
has determined that interval does not address the identified unsafe condition soon enough to ensure an adequate level of safety for the affected fleet. In developing an appropriate compliance time for this AD, the FAA considered the degree of urgency associated with the subject unsafe condition and the manufacturers recommendation. In light of all of these factors, the FAA
finds that a compliance time of within 660 hours TIS or 6 months, whichever occurs first, represents an appropriate interval of time for affected helicopters to continue to operate without compromising safety.
Although paragraph 5 of EASA AD
20180206 specifies that operators may contact the manufacturer for instructions if there are signs of degradation on the MRM inner race, paragraph i3 of this AD requires operators to repair or replace the MRM
if there is any degradation as indicated by damage to the retaining rings including but not limited to cracks, scratches, and gouges, deterioration, or wear.

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