Airworthiness Directives; Robinson Helicopter Company

[Federal Register Volume 89, Number 232 (Tuesday, December 3, 2024)]
[Rules and Regulations]
[Pages 95717-95719]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-28178]



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Federal Register / Vol. 89, No. 232 / Tuesday, December 3, 2024 / 
Rules and Regulations

[[Page 95717]]



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:
    <bullet> 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.
    <bullet> 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: [email protected].

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

[[Page 95718]]

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

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

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.

[[Page 95719]]

(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: [email protected].
    (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: [email protected].

(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: robinsonheli.com">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 Administration (NARA). For information on the availability 
of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email: [email protected].

    Issued on November 4, 2024.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2024-28178 Filed 12-2-24; 8:45 am]
BILLING CODE 4910-13-P

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