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Federal Register / Vol. 86, No. 43 / Monday, March 8, 2021 / Rules and Regulations issuing this AD to address the unsafe condition on these products.
DATES: This AD is effective April 12, 2021.
The Director of the Federal Register approved the incorporation by reference of a certain document listed in this AD
as of April 12, 2021.
ADDRESSES: For service information identified in this final rule, contact Robinson Helicopter Company, 2901
Airport Drive, Torrance, CA 90505;
telephone 3105390508; fax 310539
5198; or at https robinsonheli.com/
technical-support/. You may view a copy of the referenced service information at the FAA, Office of the Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N321, Fort Worth, TX 76177.
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. FAA2017
0682; 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, any comments received, and other information. The address for Docket Operations is 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:
Danny Nguyen, Aerospace Engineer, Los Angeles ACO Branch, FAA, 3960
Paramount Blvd., Lakewood, California 90712; telephone 5626275247; email danny.nguyen@faa.gov.
SUPPLEMENTARY INFORMATION:

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Discussion The FAA issued a supplemental notice of proposed rulemaking SNPRM
to amend 14 CFR part 39 by adding an AD that would apply to Robinson Model R66 helicopters with a T/R drive shaft assembly part number P/N D2243
without B90011 modification installed.
The SNPRM published in the Federal Register on July 28, 2020 85 FR 45360.
The FAA preceded the SNPRM with a notice of proposed rulemaking NPRM
that published in the Federal Register on March 30, 2018 83 FR 13706. The NPRM was prompted by two incidents of forward hanger bearing failure of the T/R drive shaft assembly because the bearing was undersized for its housing.
Consequently, the bearing was spinning at a speed that caused excessive heating of the bearing during operation and led to the breakdown of the bearings grease
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and ultimately seizure of the C64716
bearing.
To correct this condition, Robinson initially issued R66 Service Bulletin SB14, dated June 25, 2015 SB14, for certain serial-numbered helicopters, which specified installing a temperature recorder on the T/R drive shaft forward hanger bearing assembly and inspecting the temperature recorder during preflight checks and during each 100hour inspection. If the bearing was found running hot, then Robinson advised upgrading the bearing to a newer design.
Following additional reports of overheating forward hanger bearing assemblies, Robinson superseded SB14
with R66 Service Bulletin SB20, dated November 7, 2016 SB20, which affected additional serial-numbered helicopters and specified modifying T/
R drive shaft assembly P/Ns D2243 and D2244 by using kit Robinson KI235
R66 TRDS Forward Yoke Assembly and Hanger Installation Kit Instructions, Revision A, dated June 23, 2015 KI
235 and installing yoke assembly P/N
D2245. This installation has an improved, larger bearing that spins with less friction. SB20 also specified inspecting the forward and aft sides of the hanger and damper bearings for a minimum of 0.5 inch in length of sealant on the junction of the black seal and bearing outer race and applying sealant if there was less than 0.5 inch in length of sealant.
Robinson revised SB20 with R66
Service Bulletin SB20A, dated June 6, 2017 SB20A, to clarify that helicopters with either T/R drive shaft assembly P/N D2243 with modification B90011 or P/N D2244 installed include the upgraded bearing and do not require kit KI235.
Robinson later revised SB20A with R66 Service Bulletin SB20B, dated December 20, 2017 SB20B, which updates writing practices and organizes the procedures into two separate sections, clarifies the Rotorcraft Affected section, and reduces the helicopters that need to perform the inspection and sealant application procedures to just helicopters without the latest version damper and housing bearings.
The NPRM proposed to require within 100 hours time-in-service TIS
replacing an affected T/R drive shaft forward yoke assembly with T/R drive shaft yoke assembly P/N D2245. The NPRM proposed to require inspections of the forward and aft sides of the hanger bearing and the damper bearing for sealant, and depending on the results of the inspections applying sealant. The SNPRM proposed to revise
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the NPRM by expanding the applicability, changing the proposed requirements, and correcting nomenclature. The FAA is issuing this AD to address the unsafe condition on these products.
Comments The FAA gave the public the opportunity to comment on the proposed rulemaking. The following presents the comments received on the SNPRM and the FAAs response to each comment.
Request: Robinson requested the FAA
change the note to the Applicability paragraph to identify certain serialnumbered helicopters that had T/R
drive shaft assembly P/N D2244
installed during production and clarify that these helicopters are not affected by this AD. Robinson explained that the specified serial-numbered helicopters with T/R drive shaft assembly P/N
D2244 installed have the larger hanger bearing, which is not affected by this AD, and clarified that P/N D224
5 is a sub-assembly upgrade to P/N
D2244.
FAA Response: The FAA agrees and has revised that note in this final rule to identify the serial-numbered helicopters with T/R drive shaft assembly P/N D2244 installed during production and clarify that this partnumbered T/R drive shaft assembly is not affected by this AD.
Request: Robinson requested that the FAA change the exception in paragraph e1i of this AD about not requiring the discarding of removed nuts and palnuts and stated that exception implies that the nuts and palnuts may be reused. Robinson explained that FAA
Advisory Circular AC 43.131B
Section 7122 d specifies that these nuts should be discarded and referenced Robinson service information that specifies upgrading certain nuts any time maintenance is done. Robinson also stated that the KI235 kit includes all required nuts and palnuts to replace discarded hardware.
FAA Response: The FAA disagrees.
The FAA cannot require discarding of parts in an AD. Paragraph d, section 7
122, of FAA AC 43.131B states that the removed nuts should never be reused and should be replaced with new ones when removed. Accordingly, the FAA
has added language to the exception stating that this AD requires removing the affected parts from service.
FAAs Determination The FAA has reviewed the relevant information, considered the comments received, and determined that an unsafe condition exists and is likely to exist or
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