DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0682; Product Identifier 2017-SW-028-AD]
RIN 2120-AA64

Airworthiness Directives; Robinson Helicopter Company Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Supplemental notice of proposed rulemaking (SNPRM); reopening
of comment period.

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SUMMARY: The FAA is revising an earlier proposal for Robinson
Helicopter Company (Robinson) Model R66 helicopters that proposed to
require replacing a certain part-numbered tail rotor (T/R) drive shaft
yoke assembly (yoke assembly) and inspecting for sealant. The NPRM was
prompted by reports of T/R drive shaft forward hanger bearing failures.
This action revises the NPRM by expanding the applicability, changing
the proposed requirements, and correcting nomenclature. Since this
imposes an additional burden over that proposed in the NPRM, the FAA is
reopening the comment period to allow the public the chance to comment
on these changes.

DATES: The comment period for the NPRM published in the Federal
Register on March 30, 2018 (83 FR 13706), is reopened.

The FAA must receive comments on this SNPRM by September 11, 2020.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:

Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the
instructions for submitting comments.

Fax: 202-493-2251.

Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.

Hand Delivery: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590, between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays.

For service information identified in this SNPRM, contact Robinson
Helicopter Company, 2901 Airport Drive, Torrance, CA 90505; telephone
310-539-0508; fax 310-539-5198; or at https://www.robinsonheli.com. You
may view this 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 in 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 SNPRM, any comments
received, and other information. The street address for Docket
Operations is listed above. Comments will be available in the AD docket
shortly after receipt.

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:

Comments Invited

The FAA invites you to participate in this rulemaking by submitting
written comments, data, or views. The most helpful comments reference a
specific portion of the proposal, explain the reason for any
recommended change, and include supporting data. To ensure the docket
does not contain duplicate comments, commenters should send only one
copy of written comments, or if comments are filed electronically,
commenters should submit only one time.

Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will file in the docket all comments received, as well
as a report summarizing each substantive public contact with FAA
personnel concerning this proposed rulemaking. Before acting on this
proposal, the FAA will consider all comments received on or before the
closing date for comments. The FAA will consider comments filed after
the comment period has closed if it is possible to do so without
incurring expense or delay. The FAA may change this proposal in light
of the comments received.

Confidential Business Information

Confidential Business Information (CBI) is commercial or financial
information that is both customarily and actually treated as private by
its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552),
CBI is exempt from public disclosure. If your comments responsive to
this SNPRM contain commercial or financial information that is customarily
treated as private, that you actually treat as private, and that is
relevant or responsive to this SNPRM, it is important that you clearly
designate the submitted comments as CBI. Please mark each page of your
submission containing CBI as "PROPIN." The FAA will treat such marked
submissions as confidential under the FOIA, and they will not be placed
in the public docket of this SNPRM. Submissions containing CBI should
be sent to Danny Nguyen, Aerospace Engineer, Los Angeles ACO Branch,
FAA, 3960 Paramount Blvd., Lakewood, California 90712; telephone 562-
627-5247; email danny.nguyen@faa.gov. Any commentary that the FAA
receives which is not specifically designated as CBI will be placed in
the public docket for this rulemaking.

Discussion

The FAA issued a Notice of proposed rulemaking (NPRM), which
proposed to amend 14 CFR part 39 by adding an AD that would apply to
Robinson Model R66 helicopters, serial numbers 0003 through 0752, with
a T/R drive shaft assembly part number (P/N) D224-3 or D224-4
installed. The NPRM published in the Federal Register on March 30, 2018
(83 FR 13706). The NPRM proposed to require replacing the yoke
assembly, visually inspecting for sealant, and applying sealant if
needed to prevent seal rotation.

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 actions proposed by the NPRM were intended to prevent failure
of the T/R drive shaft forward bearing and subsequent loss of
helicopter control.

Comments

After the NPRM was published, the FAA received comments from
Robinson. The following presents the comments received on the NPRM and
the FAA's response to each comment.

Request for Changes to the Preamble and Nomenclature

Request: Robinson requested the description of what prompted this
AD in the SUMMARY section be revised from reports of T/R drive shaft
failures to reports of bearing failures because there have been no T/R
drive shaft failures, only bearing failures.

FAA Response: The FAA agrees and has revised that statement in this
SNPRM.

Request: Robinson requested standardizing nomenclature by changing
instances of "yoke assembly" to "hanger bearing" throughout the AD
to minimize confusion. Robinson stated that although the bearing is
pressed onto a yoke, the important point is to upgrade the bearing.

FAA Response: The FAA agrees to clarify nomenclature pertaining to
the forward hanger bearing when discussing T/R drive shaft assembly P/N
D224-3 and P/N D224-4. However, the FAA continues to use the
nomenclature of yoke assembly for T/R drive shaft assembly P/N D224-5
to match nomenclature stated in Robinson service information.

Request: Robinson requested numerous changes to the Discussion
section to provide a simplified explanation of the bearing failure--
noting that the explanation as published in the NPRM has technical
errors and that the C647 callout is not beneficial because there was no
customer visibility of the C647 P/N until data plates were added
recently, and to provide a description of the upgraded bearing design,
clarify the explanation of SB-20 and SB-20A, add an explanation of SB-
20B, identify that the sealant inspection and application aspects of
the SB are separate from this AD, and state that bearing failure does
not cause loss of helicopter control.

FAA Response: The purpose of the Discussion section is to explain
the unsafe condition and the FAA's justification for issuing AD action.
It may include, but is not limited to, providing the following types of
information: the circumstances that created the need to correct the
unsafe condition, historical information, consequences if the unsafe
condition is not corrected, and any other information that supports the
AD action. Robinson's requested language that corrects information in
the Discussion section has been incorporated in this SNPRM. Any
requested changes that do not correct information have not been
incorporated.

Request: Robinson proposed changes to the Related Service
Information section that delete the pilot caution reference. Robinson
stated it is peripheral to the bearing upgrade and obsolete due to
supersedure of SB-14. Robinson also requested adding a reference to SB-
20B, adding clarification that the bearing upgrade is only for T/R
drive shaft assembly P/N D223-3, and removing information related to
the sealant inspection and application.

FAA Response: The purpose of the Related Service Information
section is to describe service information that is relevant to the AD
action and give a brief description of the specified procedures.
Service information documents that are relevant to an AD action may
contain other information as well. Any proposed changes that correct
information in the Related Service Information section have been
incorporated in this SNPRM. Any proposed changes that do not correct
information have not been incorporated.

Request for Changes to the Applicability

Request: Robinson requested the FAA revise the applicability of
this AD by removing the aircraft S/N. Robinson further stated that the
aircraft S/N may be included for reference.

FAA Response: The FAA agrees and has revised the applicability in
this SNPRM accordingly.

Request: Robinson requested the FAA remove T/R drive shaft assembly
P/N D224-4 from the applicability of this AD because T/R drive shaft
assembly P/N D224-4 incorporates the improved bearing and does not
require an upgrade. Robinson also proposed adding a note stating that
T/R drive shaft assembly P/N D224-3 with modification data plate P/N
B900-11 has previously been upgraded and does not require action per
this AD.

FAA Response: The FAA agrees except T/R drive shaft assembly P/N
D224-3 with B900-11 modification installed cannot be included in a note
because notes are for informational purposes and are not regulatory
text. This exception will be included in the applicability paragraph
instead.

Request To Change the Unsafe Condition

Request: Robinson proposed the FAA change the possible result of
the unsafe condition from "failure of the T/R drive shaft and
subsequent loss of helicopter control" to "forced landing of the
helicopter."

FAA Response: The FAA disagrees. Failure of the T/R drive shaft
bearing results in loss of T/R control, which could result in scenarios
ranging from a forced landing of the helicopter to loss of helicopter
control.

Request for Changes to the Required Actions

Request: Robinson requested the FAA change the Required Actions
paragraph to delete the requirements to install T/R drive shaft
assembly P/N D224-5 and inspect and apply sealant. Robinson requested
the FAA require upgrading an affected T/R drive shaft assembly P/N
D224-3 using Robinson KI-235 or replacing an affected T/R drive shaft
assembly P/N D224-3 with T/R drive shaft assembly P/N D224-4 instead.

FAA Response: The FAA agrees, except for using the wording Robinson
KI-235, as this SNPRM specifically specifies installing Robinson KI-235
using KI-235 R66 TRDS Forward Yoke Assembly and Hanger Installation Kit
Instructions, Revision A, dated June 23, 2015.

Additional Changes Since the NPRM Was Issued

Since the FAA issued the NPRM, the fleet size has increased from
249 helicopters to 290 helicopters and the website address for Robinson
has changed. This SNPRM updates this information.

Additionally, the FAA has determined that it is necessary to
prevent installation of an affected T/R drive shaft assembly on any
Model R66 helicopter as a replacement part. Accordingly, this SNPRM
proposes to prohibit this installation.

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.

FAA's Determination

The FAA is proposing this SNPRM after evaluating all known relevant
information and determining that an unsafe condition is likely to exist
or develop on other helicopters of the same type design. Certain
changes described above expand the scope of the original NPRM. As a
result, the FAA has determined that it is necessary to reopen the
comment period to provide additional opportunity for the public to
comment on this SNPRM.

Proposed Requirements of This SNPRM

This SNPRM proposes to require, within 100 hours TIS, either
installing Robinson field kit P/N KI-235 or replacing an affected T/R
drive shaft assembly with T/R drive shaft assembly P/N D224-4. This
SNPRM also proposes to prohibit installing an affected T/R drive shaft
assembly on any helicopter.

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 proposed 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 proposed AD does not.

Costs of Compliance

The FAA estimates that this proposed AD affects 290 helicopters of
U.S. Registry. Labor rates are estimated at $85 per work-hour. Based on
these estimates, the FAA estimates that operators may incur the
following costs in order to comply with this proposed AD.

Installing Robinson field kit KI-235 would take about 6 work-hours
and parts would 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 would take
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 has determined that this proposed AD will not have
federalism implications under Executive Order 13132. This proposed 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 above, I certify that this proposed
regulation:

(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.

The Proposed Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA proposed to amend 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 (AD):