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2024-23-01 ROBINSON HELICOPTER COMPANY: Amendment 39-22880; Docket No. FAA-2024-1477; Project Identifier AD-2023-01015-R. 
(a) EFFECTIVE DATE

    This airworthiness directive (AD) is effective January 7, 2025.

(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,  with  riveted  belt  tension  clutch
    actuator brackets part number A185-1, A185-2, or A185-5  (bracket(s)),
    installed.

NOTE 1  TO PARAGRAPH (c): Helicopters  with an  R44 Cadet designation  are
Model R44 helicopters.

NOTE 2 TO PARAGRAPH (c): Brackets attached to the fan scroll housing  with
screws are not applicable to this AD.

(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 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  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  \5/32\-inch 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 flight crew.

(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:
    AMOC@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) 627-5226; email: Charles.L.Ayala@faa.gov.

(k) MATERIAL INCORPORATED BY REFERENCE

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

(2) You must use this material 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  3  TO  PARAGRAPH (k)(2)(i):  The  material  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  material  identified  in this  AD,
    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 material  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 Admin-
    istration (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 November 4, 2024. Victor Wicklund, Deputy Director, Compliance &
Airworthiness Division, Aircraft Certification Service.

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.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-1477; Project Identifier AD-2023-01015-R;
Amendment 39-22880; AD 2024-23-01]
RIN 2120-AA64

Airworthiness Directives; Robinson Helicopter Company

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain Robinson Helicopter Company Model R44 and R44 II helicopters.
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. This AD requires inspecting each
bracket and, depending on the results, accomplishing additional
inspections or taking any necessary corrective actions. The FAA is
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective January 7, 2025.

The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of January 7, 2025.

ADDRESSES:

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 final rule, 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.

Material Incorporated by Reference:

For Robinson Helicopter Company material identified in
this AD, contact Robinson Helicopter Company, Technical Support
Department, 2901 Airport Drive, Torrance, CA 90505; phone: (310) 539-
0508; fax: (310) 539-5198; email: robinsonheli.com">ts1@robinsonheli.com; or at
robinsonheli.com.

You may view this material 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. It is also available at
regulations.gov under Docket No. FAA-2024-1477.

Other Related Material: For other related Robinson Helicopter
Company material identified in this AD, 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:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to certain serial-numbered
Robinson Helicopter Company Model R44 and Model R44 II helicopters. The
NPRM published in the Federal Register on June 27, 2024 (89 FR 53534).
The NPRM was prompted by 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.

In the NPRM, the FAA proposed to require, with the fanwheel
removed, inspecting each bracket for looseness and fretting. Depending
on the results of the inspection in the NPRM, the FAA proposed to
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. The FAA is issuing this AD to
address the unsafe condition on these products.

Discussion of Final Airworthiness Directive

Comments

The FAA received a comment from one commenter, Robinson Helicopter
Company. The following presents the comment received on the NPRM and
the FAA's response to the comment.

Request To Change the Applicability

Robinson Helicopter Company requested the FAA revise the
applicability paragraph to identify only riveted A185-1, A185-2, and
A185-5 brackets. Robinson Helicopter Company stated that some
helicopters within the applicable serial number ranges have been
retrofitted with the latest design installation that utilizes screws as
the method of attachment to the fan scroll housing instead of rivets
and are not subject to this AD.

The FAA agrees and has revised the applicability paragraph of this
AD to clarify that only certain riveted brackets are applicable. The
FAA also added a note to the applicability paragraph of this AD to
further clarify that brackets installed to the fan scroll housing with
screws are not applicable to this AD.

Conclusion

The FAA reviewed the relevant data, considered the comment
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for minor editorial changes and
other changes described previously, this AD is adopted as proposed in
the NPRM. None of the changes will increase the economic burden on
any operator.

Material Incorporated by Reference 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 material
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 is incorporated by reference in this AD. SL-74B is not
incorporated by reference in this AD because this AD does not apply to
Robinson Helicopter Company Model R22 helicopters.

This material 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.

Other Related Material

The FAA reviewed Robinson Helicopter Company R44 Service Bulletin
SB-113, dated March 16, 2023 (SB-113). This material specifies
procedures for inspecting the A185 brackets to ensure the brackets are
attached to the fan scroll housing with \5/32\-inch rivets. This
material 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.

Differences Between This AD and the Referenced Material

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

Costs of Compliance

The FAA estimates that this AD affects 1,686 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 AD.

Inspecting the brackets (three brackets per helicopter) for
looseness and fretting will take 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 will take
0.25 work-hour, for an estimated cost of $21 per helicopter.

If required, replacing the fan scroll housing will take 5 work-
hours and parts will 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 will take 1 work-hour, for an estimated
cost of $85 per helicopter.

If required, replacing a bracket or inner plate will take 1 work-
hour and parts will cost $175, for an estimated cost of $260 per part
replacement.

If required, repairing each rivet hole (per bracket) will take 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 will 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

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 above, 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.

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: