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2021-04-12 ROBINSON HELICOPTER COMPANY:
Amendment 39-21433; Docket No. FAA-2017-0682; Product Identifier 2017-SW-028-AD.

(a) APPLICABILITY

    This  airworthiness  directive  (AD)  applies  to  Robinson Helicopter
    Company (Robinson) Model R66 helicopters, certificated in any category
    with a tail rotor (T/R) drive shaft assembly part number  (P/N) D224-3
    without B900-11 modification installed.

Note 1 to paragraph (a): Helicopters  with  serial  number  (S/N) 0631 and
subsequent had T/R drive shaft assembly  P/N D224-4 installed  during pro-
duction, which is not affected by this AD.

(b) UNSAFE CONDITION

    This AD defines the unsafe condition  as failure  of a T/R drive shaft
    forward hanger bearing.  This condition could result in failure of the
    T/R drive shaft and subsequent loss of helicopter control.

(c) EFFECTIVE DATE

    This AD is effective April 12, 2021.

(d) COMPLIANCE

    You are  responsible for  performing each  action required  by this AD
    within  the  specified  compliance time  unless  it  has already  been
    accomplished prior to that time.

(e) REQUIRED ACTIONS

(1) Within 100 hours time-in-service, do one of the following:

(i) Install Robinson  kit  P/N KI-235  using  KI-235 R66 TRDS Forward Yoke
    Assembly and Hanger Installation Kit Instructions,  Revision A,  dated
    June 23, 2015, except where the service information specifies discard-
    ing parts,  you are required  to  remove  those parts from service in-
    stead.

(ii) Replace the entire  T/R drive shaft assembly  with  T/R  drive  shaft
     assembly P/N D224-4.

(2) As of the effective date of this AD,  do not install a T/R drive shaft
    assembly P/N D224-3 without B900-11 modification on any helicopter.

(f) ALTERNATIVE METHODS OF COMPLIANCE (AMOC)

(1) The Manager, Los Angeles ACO Branch,  FAA,  may approve AMOCs for this
    AD.  Send  your  proposal  to:  Danny Nguyen,  Aerospace Engineer, Los
    Angeles ACO Branch,  FAA,  3960 Paramount Blvd.,  Lakewood, California
    90712; telephone 562-627-5247; email 9-ANM-LAACO-AMOC-REQUESTS@faa.
    gov.

(2) For operations conducted under a 14 CFR part 119 operating certificate
    or under 14 CFR part 91,  subpart K, the FAA suggests that  you notify
    your  principal  inspector,  or  lacking  a  principal  inspector, the
    manager of the local  flight standards district office  or certificate
    holding district office before  operating any aircraft complying  with
    this AD through an AMOC.

(g) RELATED INFORMATION

    For service information identified in this AD,  contact Robinson Heli-
    copter Company, 2901 Airport Drive, Torrance, CA 90505; telephone 310-
    539-0508; fax 310-539-5198 or at https://www.robinsonheli.com. You may
    view a copy of the service information  at  the  FAA,  Office  of  the
    Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-321,
    Fort Worth, TX 76177.

(h) MATERIAL INCORPORATED BY REFERENCE

(1) The Director of the Federal Register  approved  the  incorporation  by
    reference (IBR) of  the service information  listed in this  paragraph
    under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use  this service information as applicable to do the actions
    required by this AD, unless the AD specifies otherwise.

(i) Robinson KI-235 R66 TRDS Forward Yoke Assembly and Hanger Installation
    Kit Instructions, Revision A, dated June 23, 2015.

(ii) [Reserved]

(3) For service information identified in this AD,  contact Robinson Heli-
    copter Company, 2901 Airport Drive, Torrance, CA 90505; telephone 310-
    539-0508; fax 310-539-5198; or at https://www.robinsonheli.com.

(4) You may view  this  service  information  at  the  FAA,  Office of the
    Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-321,
    Fort Worth, TX 76177.

(5) You may view  this service information  that is incorporated by refer-
    ence at the National Archives and Records Administration  (NARA).  For
    information on the availability  of  this  material  at  NARA,  email:
    fedreg.legal@nara.gov,  or  go  to:  https://www.archives.gov/federal-
    register/cfr/ibr-locations.html.

(i) SUBJECT

    Joint Aircraft Service Component (JASC) Code:  6510,  Tail Rotor Drive
    Shaft.

Issued on February 8, 2021. Lance T Gant, Director, Compliance & Airworth-
iness Division, Aircraft Certification Service.

FOR FURTHER INFORMATION CONTACT:  Danny  Nguyen,  Aerospace Engineer,  Los
Angeles ACO Branch, FAA, 3960 Paramount Blvd., Lakewood, California 90712;
telephone 562-627-5247; email danny.nguyen@faa.gov.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0682; Product Identifier 2017-SW-028-AD; Amendment
39-21433; AD 2021-04-12]
RIN 2120-AA64

Airworthiness Directives
; Robinson Helicopter Company Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
Robinson Helicopter Company (Robinson) Model R66 helicopters. This AD
was prompted by reports of tail rotor (T/R) drive shaft forward hanger
bearing failures. This AD requires installing a certain part numbered
kit and removing parts from service or replacing a certain part-
numbered T/R drive shaft assembly. This AD also prohibits the
installation of certain parts. The FAA is 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 310-539-0508; fax 310-539-5198; 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 6N-321, 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. FAA-2017-
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 562-627-5247; email danny.nguyen@faa.gov.

SUPPLEMENTARY INFORMATION:

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)
D224-3 without B900-11 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 bearing's grease and ultimately seizure of the C647-16
bearing.
To correct this condition, Robinson initially issued R66 Service
Bulletin SB-14, dated June 25, 2015 (SB-14), 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 100-
hour 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 SB-14 with R66 Service Bulletin SB-20,
dated November 7, 2016 (SB-20), which affected additional serial-
numbered helicopters and specified modifying T/R drive shaft assembly
P/Ns D224-3 and D224-4 by using kit Robinson KI-235 R66 TRDS Forward
Yoke Assembly and Hanger Installation Kit Instructions, Revision A,
dated June 23, 2015 (KI-235) and installing yoke assembly P/N D224-5.
This installation has an improved, larger bearing that spins with less
friction. SB-20 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 SB-20 with R66 Service Bulletin SB-20A, dated June
6, 2017 (SB-20A), to clarify that helicopters with either T/R drive
shaft assembly P/N D224-3 with modification B900-11 or P/N D224-4
installed include the upgraded bearing and do not require kit KI-235.
Robinson later revised SB-20A with R66 Service Bulletin SB-20B,
dated December 20, 2017 (SB-20B), 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 D224-5. 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 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 FAA's response to each comment.
Request: Robinson requested the FAA change the note to the
Applicability paragraph to identify certain serial-numbered helicopters
that had T/R drive shaft assembly P/N D224-4 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 D224-4 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 D224-4.
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 D224-4 installed during production and clarify that
this part-numbered T/R drive shaft assembly is not affected by this AD.
Request: Robinson requested that the FAA change the exception in
paragraph (e)(1)(i) 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) 43.13-1B Section 7-122 (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 KI-235 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 43.13-1B
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.

FAA's 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 develop on other products of the same type design and that
air safety and the public interest require adopting the AD requirements as
proposed with the changes described previously. These changes are
consistent with the intent proposed in the SNPRM for correcting the
unsafe condition and will neither increase the economic burden on any
operator nor increase the scope of the AD.

Related Service Information Under 1 CFR Part 51

The FAA reviewed KI-235. This service information provides
instructions for installing the newly designed yoke assembly, P/N D224-5.
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.

Related Service Information

The FAA has reviewed SB-14, which specifies installing a
temperature recorder on the T/R drive shaft forward hanger bearing
assembly and inspecting the temperature during preflight checks and
during each 100-hour inspection. If the temperature of the bearing is
found running hot, then Robinson advises upgrading the bearing to a
newer design (kit P/N KI-235). This service information also specifies
adding a caution page to the Pilot Operating Handbook regarding the
overheating bearing assemblies. This service information was superseded
by SB-20.
The FAA has reviewed SB-20, SB-20A, and SB-20B, which specify
upgrading the forward hangar bearing assembly of certain T/R drive
shaft assemblies to the newer design with kit P/N KI-235 if not
previously done. For certain installations, this service information
contains procedures for inspecting for sealant and applying sealant to
the damper and hanger bearings if needed to prevent seal rotation. This
service information also specifies removing the caution page from the
Pilot Operating Handbook regarding the overheating bearing assemblies
that was added by SB-14.

Differences Between This AD and the Service Information

SB-20 specifies replacing the yoke assembly and applying sealant to
the bearing seals within the next 100 flight hours or by January 31,
2017, whichever comes first, and SB-20A and SB-20B continue the
compliance time of no later than January 31, 2017. This AD does not
have a calendar time compliance requirement. SB-20, SB- 20A, and SB-20B
specify inspecting for sealant and applying sealant to the damper and
hanger bearings if needed, while this AD does not.

Costs of Compliance

The FAA estimates that this AD affects 290 helicopters of U.S.
Registry. The FAA estimates that operators may incur the following
costs in order to comply with this AD. Labor costs are estimated at $85
per work-hour.
Installing Robinson field kit KI-235 takes about 6 work-hours and
parts cost about $950, for an estimated cost of $1,460 per helicopter.
As an option, replacing an affected T/R drive shaft assembly P/N D224-3
with T/R drive shaft assembly P/N D224-4 takes about 5 work-hours and
parts cost about $4,400, for an estimated cost of $4,825 per
helicopter.

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 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.

Regulatory Findings

The FAA determined that 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, 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.

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: