DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-1477; Project Identifier AD-2023-01015-R]
RIN 2120-AA64

Airworthiness Directives; Robinson Helicopter Company Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for certain Robinson Helicopter Company Model R44 and R44 II
helicopters. This proposed AD was prompted by several reports of failed
clutch actuators and failed rivets attaching the belt tension clutch
actuator brackets (bracket) to the fan scroll housing. This proposed AD
would require inspecting each bracket and, depending on the results,
accomplishing additional inspections or taking any necessary corrective
actions. The FAA is proposing this AD to address the unsafe condition
on these products.

DATES: The FAA must receive comments on this proposed AD by August 12,
2024.

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 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: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2024-1477; 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 NPRM, any comments received, and other
information. The street address for Docket Operations is listed above.
Material Incorporated by Reference:
For Robinson Helicopter Company service information,
contact Robinson Helicopter Company, Technical Support Department, 2901
Airport Drive, Torrance, CA 90505; phone (310) 539-0508; fax (310) 539-
5198; email ts1@robinsonheli.com; or at robinsonheli.com.
You may view this service information at the FAA, Office
of the Regional Counsel, Southwest Region, 10101 Hillwood Parkway, Room
6N-321, Fort Worth, TX 76177. For information on the availability of
this material at the FAA, call (817) 222-5110.
Other Related Service Information: For additional Robinson
Helicopter Company service information, use the Robinson Helicopter
Company contact information under Material Incorporated by Reference
above.

FOR FURTHER INFORMATION CONTACT: Charles Ayala, Aviation Safety
Engineer, FAA, 3960 Paramount Boulevard, Lakewood, CA 90712; phone:
(562) 627-5226; email: Charles.L.Ayala@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under ADDRESSES. Include ``Docket No. FAA-2024-1477; Project Identifier
AD-2023-01015-R'' at the beginning of your comments. The most helpful
comments reference a specific portion of the proposal, explain the
reason for any recommended change, and include supporting data. The FAA
will consider all comments received by the closing date and may amend
this proposal because of those comments.
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 post all comments received, without change, to
regulations.gov, including any personal information you provide. The
agency will also post a report summarizing each substantive verbal
contact received about this NPRM.

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 NPRM 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 NPRM, 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 NPRM. Submissions containing CBI should be sent to
Charles Ayala, Aviation Safety Engineer, FAA, 3960 Paramount Boulevard,
Lakewood, CA 90712; phone: (562) 627-5226; email:
Charles.L.Ayala@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.

Background

The FAA received five reports of failed clutch actuators and failed
rivets attaching the clutch actuator bracket, part number A185-1, A185-
2, and A185-5 (bracket), to the fan scroll housing on Robinson
Helicopter Company Model R44 II helicopters. According to Robinson
Helicopter Company, in all of these occurrences, the bracket separated
from the fan scroll housing. In four of the reports, this separation of
the bracket caused a failure of the belt tension actuator. Further
investigation revealed the failure of the rivets attaching the bracket
to the fan scroll housing was caused by excessive vibration of the fan
scroll housing due to the design of the fan scroll housing, including
the quantity and size of the rivets. Because of design similarity,
Robinson Helicopter Company Model R44 helicopters are also affected by
this unsafe condition.
Accordingly, the FAA proposes to adopt a new AD for certain serial-
numbered Robinson Helicopter Company Model R44 and R44 II helicopters
to detect and correct loose and missing brackets and rivets.
Helicopters with subsequent serial numbers were manufactured with steel
hex-drive screws attaching the brackets to the scroll instead of
rivets, and therefore are not susceptible to rivet failures. This
condition, if not addressed, could result in detachment of the bracket
causing failure of the clutch actuator assembly, loss of main and tail
rotor drive, and subsequent loss control of the helicopter.

FAA's Determination

The FAA is issuing this NPRM after determining that the unsafe
condition described previously is likely to exist or develop on other
products of the same type design.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Robinson Helicopter Company R22 Service Letter SL-
74B (SL-74B), and R44 Service Letter SL-61B (SL-61B), each Revision B
and dated March 16, 2023 (co-published as one document). This service
information specifies procedures for inspecting the A185 brackets for
looseness and ensuring that a total of 12 rivets attach the A185
brackets to the fan scroll housing, and corrective actions as necessary
including repairing rivet holes; replacing the scroll; replacing any
\1/8\-inch rivets with \5/32\-inch rivets; enlarging rivet holes; and
applying a torque seal. SL-61B would be incorporated by reference in
this proposed AD; SL-74B would not be incorporated by reference in this
proposed AD because this proposed AD would not apply to Robinson
Helicopter Company Model R22 helicopters.
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.

Other Related Service Information

The FAA also reviewed Robinson Helicopter Company R44 Service
Bulletin SB-113, dated March 16, 2023 (SB-113). This service
information specifies procedures for inspecting the A185 brackets to
ensure the brackets are attached to the fan scroll housing with \5/32\-
inch rivets. This service information also specifies repairing the
scroll if there are less than 12 rivets, if \5/32\-inch rivets are not
installed, if the brackets are loose, or if there is any fretting.

Proposed AD Requirements in This NPRM

For certain Robinson Helicopter Company Model R44 and R44 II
helicopters, this proposed AD would require, with the fanwheel removed,
inspecting each bracket for looseness and fretting. Depending on the
results, this proposed AD would require additional actions such as
inspecting the fiberglass and rivet holes of the fan scroll housing for
delamination, inspecting the quantity and size of the fan scroll
housing rivets, replacing the fan scroll housing, replacing brackets
and rivets, and applying a horizontal torque stripe to each rivet.

Differences Between This Proposed AD and the Service Information

This proposed AD would require inspecting the brackets for fretting
and the fiberglass and rivet holes for delamination, and SL-61B does
not contain those actions. SL-61B specifies procedures for repairing
the fan scroll housing rivet holes, whereas this proposed AD would
require making that repair in accordance with FAA-approved procedures.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 1,686 helicopters of U.S. registry. Labor rates are estimated at
$85 per work-hour. Based on these numbers, the FAA estimates the
following costs to comply with this proposed AD.
Inspecting the brackets (three brackets per helicopter) for
looseness and fretting would take approximately 0.25 work-hour, for an
estimated cost of $21 per helicopter and $35,406 for the U.S. fleet.
If required, inspecting the fiberglass for delamination would take
approximately 0.25 work-hour, for an estimated cost of $21 per
helicopter.
If required, replacing the fan scroll housing would take
approximately 5 work-hours and parts would cost $3,720, for an
estimated cost of $4,145 per helicopter.
If required, inspecting all brackets, each inner plate, and each
fan scroll housing rivet hole would take approximately 1 work-hour, for
an estimated cost of $85 per helicopter.
If required, replacing a bracket or inner plate would take
approximately 1 work-hour and parts would cost approximately $175, for
an estimated cost of $260 per part replacement.
If required, repairing each rivet hole (per bracket) would take
approximately 1.5 work-hours for an estimated cost of $128 per bracket.
Replacing a rivet (if required) and applying a torque stripe to
each rivet would each take a minimal amount of time with a nominal
parts cost.

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 proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would 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 this proposed
regulation:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Would not affect intrastate aviation in Alaska, and
(3) Would 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 proposes 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: