[4910-13-P]
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 [INSERT DATE 45
DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL REGISTER].
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. FAA2024-1477; 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) 2225110.
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) 6275226; 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 SB113, 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 workhours 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 workhour 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.
§ 39.13 [Amended]
2. The FAA amends § 39.13 by adding the following new airworthiness directive:
Robinson Helicopter Company: Docket No. FAA-2024-1477; Project Identifier AD2023-01015-R.
(a) Comments Due Date
The FAA must receive comments on this airworthiness directive (AD) by
[INSERT DATE 45 DAYS AFTER DATE OF PUBLICATION IN THE FEDERAL
REGISTER].
(b) Affected ADs
None.
(c) Applicability
This AD applies to Robinson Helicopter Company Model R44 helicopters serial
numbers (S/Ns) up to 2480 inclusive and 30001 through 30022 inclusive, and Model R44
II helicopters S/Ns up to 14089 inclusive, certificated in any category.
Note 1 to paragraph (c): Helicopters with an R44 Cadet designation are Model
R44 helicopters.
(d) Subject
Joint Aircraft System Component (JASC) Code: 6300, Main rotor drive system
and 6700, Rotorcraft flight control.
(e) Unsafe Condition
This 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. The FAA is issuing this AD to detect and address loose and missing brackets
and rivets. The unsafe 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 of control of the helicopter.
(f) Compliance
Comply with this AD within the compliance times specified, unless already done.
(g) Required Actions
Within 300 hours time-in-service or 12 months after the effective date of this AD,
whichever occurs first, with the fanwheel removed, inspect each bracket part number
A185-1, A185-2, and A185-5 (bracket) installed on the fan scroll housing for looseness
(bracket can be moved by hand) and fretting and accomplish the actions in paragraphs
(g)(1) or (2) of this AD, as applicable.
(1) If there is no looseness of any bracket and no fretting, before further flight,
visually inspect the fiberglass adjacent to the rivets of the fan scroll housing for
delamination.
(i) If there is any delamination in the fiberglass, before further flight, remove the
fan scroll housing from service and install an airworthy fan scroll housing using 5/32inch rivets (3 rivets on each top bracket and 6 rivets on the bottom bracket). Figure 1 of
Robinson Helicopter Company R44 Service Letter SL-61B, Revision B, dated March 16,
2023 (SL-61B) depicts the location of each bracket and rivet.
(ii) If there is no delamination in the fiberglass, before further flight, inspect for
the installation of 5/32-inch rivets in all 12 locations (3 rivets on each top bracket and 6
rivets on the bottom bracket) depicted in Figure 1 of SL-61B. If a 5/32-inch rivet is not
installed in all 12 locations, before further flight, replace each incorrectly sized rivet and
each missing rivet with a 5/32-inch rivet.
(iii) Apply a horizontal torque stripe to each rivet.
(2) If any bracket is loose or has any fretting, before further flight, remove all
brackets and inner plates from the fan scroll housing and accomplish the actions in
paragraphs (g)(2)(i) through (iv) of this AD.

(i) For each bracket with fretting, before further flight, remove the bracket from
service and replace it with an airworthy bracket.
(ii) Visually inspect each bracket and inner plate for cracks and deformation,
visually inspect the fiberglass adjacent to the rivets of the fan scroll housing for
delamination, and visually inspect each fan scroll housing rivet hole for delamination and
other damage, which may be indicated by fretting.
(A) If a bracket or inner plate has any cracks or deformation, before further flight,
remove the affected part from service and replace it with an airworthy part.
(B) If there is any delamination in the fiberglass or in any fan scroll housing rivet
hole, before further flight, remove the fan scroll housing from service and install an
airworthy fan scroll housing using 5/32-inch rivets (3 rivets on each top bracket and 6
rivets on the bottom bracket). Figure 1 of SL-61B depicts the location of each bracket and
rivet.
(C) If there is other damage in any fan scroll housing rivet hole, before further
flight, repair the rivet hole in accordance with FAA-approved procedures.
(iii) After accomplishing the actions in paragraphs (g)(2)(i) and (ii) of this AD,
when installing or reinstalling the brackets and inner plates on the fan scroll housing, use
5/32-inch rivets in all 12 locations depicted in Figure 1 of SL-61B (3 rivets on each top
bracket and 6 rivets on the bottom bracket).
(iv) Apply a horizontal torque stripe to each rivet.
(h) Special Flight Permits
A one-time special flight permit may be issued in accordance with 14 CFR 21.197
and 21.199 to fly the aircraft to a location where the actions required by this AD can be
accomplished. This flight must be a non-revenue flight and limited to only essential
flightcrew.
(i) Alternative Methods of Compliance (AMOCs)
(1) The Manager, West Certification Branch, FAA, has the authority to approve
AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In
accordance with 14 CFR 39.19, send your request to your principal inspector or local
Flight Standards District Office, as appropriate. If sending information directly to the

manager of the West Certification Branch, send it to the attention of the person identified
in paragraph (j) of this AD. Information may be emailed to: 9-ANM-LAACO-AMOCREQUESTS@faa.gov.
(2) Before using any approved AMOC, notify your appropriate principal
inspector, or lacking a principal inspector, the manager of the local flight standards
district office/certificate holding district office.
(j) Related Information
For more information about this AD, contact Charles Ayala, Aviation Safety
Engineer, FAA, 3960 Paramount Boulevard, Lakewood, CA 90712; phone: (562) 6275226; email: Charles.L.Ayala@faa.gov.
(k) Material Incorporated by Reference
(1) The Director of the Federal Register approved the incorporation by reference
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 Helicopter Company R44 Service Letter SL-61B, Revision B, dated
March 16, 2023.
Note 2 to paragraph (k)(2)(i): The service information identified in paragraph
(k)(2)(i) of this AD is co-published as one document along with Robinson Helicopter
Company R22 Service Letter SL-74B, Revision B, dated March 16, 2023, which is not
incorporated by reference in this AD.
(ii) [Reserved]
(3) 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.

(4) You may view this service information at the FAA, Office of Regional
Counsel, Southwest Region, 10101 Hillwood Pkwy., Fort Worth, TX 76177. For
information on the availability of this material at the FAA, call (817) 222-5110.

(5) You may view this material at the National Archives and Records
Administration (NARA). For information on the availability of this material at NARA,
visit www.archives.gov/federal-register/cfr/ibr-locations or email
fr.inspection@nara.gov.
Issued on May 21, 2024.

James D. Foltz,
Deputy Director, Compliance & Airworthiness Division,
Aircraft Certification Service.
[FR Doc. 2024-11610 Filed: 6/26/2024 8:45 am; Publication Date: 6/27/2024]