Airworthiness Directives; Robinson Helicopter Company Helicopters

[Federal Register Volume 90, Number 108 (Friday, June 6, 2025)]
[Rules and Regulations]
[Pages 24050-24054]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-10097]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2025-0011; Project Identifier AD-2024-00618-R; 
Amendment 39-23053; AD 2025-11-07]
RIN 2120-AA64


Airworthiness Directives; Robinson Helicopter Company Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2024-19-11 
for all Robinson Helicopter Company Model R44 and R44 II helicopters. 
AD 2024-19-11 required visually inspecting a certain flex plate 
assembly (flex plate) and certain clutch shaft forward yokes (yokes), 
including each flex plate bolt, and depending on the results, taking 
corrective actions. AD 2024-19-11 also required removing certain yokes 
from service within a specified threshold, or as an alternative, 
performing in-depth inspections. Since the FAA issued AD 2024-19-11, it 
has been determined that clarifications regarding the alternative 
inspections are necessary. This AD requires the actions of AD 2024-19-
11 and clarifies that the alternative inspections are repetitive and 
adds a particular paint remover option to use when performing those 
alternative inspections. The FAA is issuing this AD to address the 
unsafe condition on these products.

DATES: This AD is effective July 11, 2025.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2025-0011; 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.

FOR FURTHER INFORMATION CONTACT: Eric Moreland, Aviation Safety 
Engineer, FAA, 3960 Paramount Boulevard, Lakewood, CA 90712; phone: 
(562) 627-5364; email: [email protected].

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 to supersede AD 2024-19-11, Amendment 39-22853 (89 FR 
78785, September 26, 2024) (AD 2024-19-11). AD 2024-19-11 applied to 
all Robinson Helicopter Company Model R44 and R44 II helicopters. The 
NPRM published in the Federal Register on January 30, 2025 (90 FR 
8499). The NPRM was prompted by reports of a fractured yoke on the main 
rotor (M/R) drive due to fatigue cracking. In the NPRM, the FAA 
proposed to continue to require requirements of AD 2024-19-11 and 
update the alternative action to repetitively inspect a yoke that has 
reached the specified threshold instead of replacing it. The FAA is 
issuing this AD to address the unsafe condition on these products.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from three commenters. Commenters 
included two individual commenters and Robinson Helicopter Company. The 
following presents the comments received on the NPRM and the FAA's 
response to each comment.
    One individual commenter supported the NPRM without change.

Request To Change the Applicable Paint Stripper

    One individual commenter requested the FAA revise the required 
paint stripper from Bonderite S-ST 5251 to Bonderite S-ST 5351.
    The FAA agrees and has revised paragraph (g) of this AD 
accordingly.

Request To Clarify Compliance Times

    Robinson Helicopter Company stated a yoke that has undergone a 
magnetic particle inspection per paragraph (g)(2)(ii)(B) [of the 
proposed AD], should be allowed to be installed, per the proposed AD 
and that clarification would be helpful to state that ``first 
installation'' also refers to the first installation after completion 
of a magnetic particle inspection. Robinson Helicopter Company 
requested the FAA revise the wording in Table 1 of the proposed AD to 
include the wording ``first installation after a magnetic particle 
inspection.''

[[Page 24051]]

    The FAA agrees. The FAA has determined that adding the wording 
``after a magnetic particle inspection'' would help clarify that the 
compliance time also applies to a yoke being installed after a magnetic 
particle inspection. The FAA has revised Table 1 of this final rule.

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting the AD as 
proposed. Accordingly, the FAA is issuing this AD to address the unsafe 
condition on these products. Except for minor editorial changes and any 
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.

Costs of Compliance

    The FAA estimates that this AD affects 1,725 helicopters of U.S. 
registry. Labor rates are estimated at $85 per hour. Based on these 
numbers, the FAA estimates the following costs to comply with this AD.
    Visually inspecting a flex plate would take 0.25 work-hour for an 
estimated cost of $21 per helicopter and $36,225 for the U.S. fleet. If 
required, replacing a flex plate would take 1 work-hour and parts would 
cost $1,240 for an estimated cost of $1,325 per helicopter.
    Visually inspecting a yoke, including inspecting each flex plate 
bolt, takes 1.25 work-hours for an estimated cost of $106 per 
helicopter and $182,850 for the U.S. fleet.
    Replacing a yoke takes 6 work-hours and parts will cost $890 for an 
estimated cost of $1,400 per helicopter and $2,415,000 for the U.S. 
fleet, per replacement cycle.
    Alternatively, removing paint and inspecting a yoke using 10X or 
higher power magnifying glass takes 1.5 work-hours for an estimated 
cost of $128 per helicopter. If required, performing a magnetic 
particle inspection takes 1.5 work-hours for an estimated cost of $128 
per helicopter.
    Applying torque to a set of bolts, nuts, and palnuts takes 1 work-
hour for an estimated cost of $85 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

    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:
0
a. Removing Airworthiness Directive 2024-19-11, Amendment 39-22853 (89 
FR 78785, September 26, 2024); and
0
b. Adding the following new airworthiness directive:

2025-11-07 Robinson Helicopter Company: Amendment 39-23053; Docket 
No. FAA-2025-0011; Project Identifier AD-2024-00618-R.

(a) Effective Date

    This airworthiness directive (AD) is effective July 11, 2025.

(b) Affected ADs

    This AD replaces AD 2024-19-11, Amendment 39-22853 (89 FR 78785, 
September 26, 2024).

(c) Applicability

    This AD applies to Robinson Helicopter Company Model R44 and R44 
II helicopters, certificated in any category.

(d) Subject

    Joint Aircraft System Component (JASC) Code 6310, Engine/
Transmission coupling.

(e) Unsafe Condition

    This AD was prompted by reports of a fractured clutch shaft 
forward yoke (yoke) on the main rotor (M/R) drive due to fatigue 
cracking. The FAA is issuing this AD to detect fatigue cracking on 
the yoke. The unsafe condition, if not addressed, could result in 
loss of M/R drive and consequent loss of control of the helicopter.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Required Actions

    (1) Within 100 hours time-in-service (TIS) after the effective 
date of this AD, accomplish the actions required by paragraphs 
(g)(1)(i) through (iii) of this AD.
    (i) Visually inspect forward flex plate assembly part number (P/
N) C947-1 (flex plate) for any loose fasteners, cracks, fretting, 
corrosion, wear, and to ensure that the washers are bonded to both 
sides of each flex plate arm, in the areas depicted in Figure 1 to 
paragraph (g)(1)(i) of this AD. If there is any loose fastener (can 
be moved by hand), crack, fretting, corrosion, or wear that consists 
of the washers not securely bonded to both sides of each flex plate 
arm, before further flight, remove the flex plate from service and 
replace it with an airworthy flex plate.
    Note 1 to paragraph (g)(1)(i): The flex plate may be installed 
in order to accomplish the visual inspection.
    Note 2 to paragraph (g)(1)(i): Robinson Helicopter Company R44 
Maintenance Manual and Instructions for Continued Airworthiness, 
Volume 1, Chapter 2 and Chapter 23, dated September 2023, contains 
information related to this AD.

[[Page 24052]]

[GRAPHIC] [TIFF OMITTED] TN06JN25.000

    (ii) Visually inspect yoke P/N C907-1 or C907-2, as applicable, 
and yoke P/N C908-1, for any cracks, corrosion, and fretting. If 
there is any crack, corrosion, or fretting, before further flight, 
remove the yoke from service and replace it with an airworthy yoke, 
and torque each newly-installed bolt, nut, and palnut P/N B330-19 
using the torque value information in Appendix 1 to this AD.
    (iii) Visually inspect each flex plate bolt for any missing or 
unaligned torque stripes, loose fasteners, loose nuts, and to ensure 
that palnuts are installed. If there is a missing or unaligned 
torque stripe, loose fastener (can be moved by hand), loose nut (can 
be turned by hand), or if a palnut is not installed, before further 
flight, remove the associated yoke from service and replace it with 
an airworthy yoke, and torque each newly-installed bolt, nut, and 
palnut P/N B330-19 using the torque value information in Appendix 1 
to this AD.
    (2) Within the compliance times specified in Table 1 to the 
introductory text of paragraph (g)(2) of this AD, accomplish the 
actions required by paragraph (g)(2)(i) of this AD or, as an 
alternative to accomplishing the actions required by paragraph 
(g)(2)(i) of this AD, accomplish the actions required by paragraph 
(g)(2)(ii) of this AD within the same compliance times.

          Table 1 to the Introductory Text of Paragraph (g)(2)
------------------------------------------------------------------------
      Helicopter groups                     Compliance times
------------------------------------------------------------------------
For Model R44 helicopters      Prior to accumulating 2,200 total hours
 having serial number 0002,     TIS on any yoke P/N C907-1 or C907-2 or
 or 0004 through 9999           within 12 years since first installation
 inclusive, except not 1140,    of yoke P/N C907-1 or C907-2 on any
 and R44 II helicopters         helicopter, whichever occurs first; or
 having serial number 1140 or   within 100 hours TIS after the effective
 10001 through 29999            date of this AD; whichever occurs later,
 inclusive.                     and thereafter before accumulating 2,200
                                total hours TIS on any yoke P/N C907-1
                                or C907-2 or within 12 years since first
                                installation after replacement or after
                                the inspection of yoke P/N C907-1 or
                                C907-2 as required in paragraph
                                (g)(2)(ii)(B) of this AD, on any
                                helicopter, whichever occurs first.
For Model R44 helicopters      Prior to accumulating 2,400 total hours
 having serial number 30001     TIS on any yoke P/N C907-1 or C907-2 or
 and subsequent.                within 12 years since first installation
                                of yoke P/N C907-1 or C907-2 on any
                                helicopter, whichever occurs first; or
                                within 100 hours TIS after the effective
                                date of this AD; whichever occurs later,
                                and thereafter before accumulating 2,400
                                total hours TIS on any yoke P/N C907-1
                                or C907-2 or within 12 years since first
                                installation after replacement or after
                                the inspection of yoke P/N C907-1 or
                                C907-2 as required in paragraph
                                (g)(2)(ii)(B) of this AD, on any
                                helicopter, whichever occurs first.
------------------------------------------------------------------------

    (i) Remove the yoke from service and replace it with an 
airworthy yoke, and torque each newly-installed bolt, nut, and 
palnut P/N B330-19 using the torque value information in Appendix 1 
to this AD, or
    (ii) With yoke P/N C907-1 or C907-2 removed, as applicable, 
remove the paint from the yoke using Cee-Bee stripper A-292 or 
Bonderite stripper S-ST 5351 without using a plastic media abrasive 
paint stripper and accomplish the actions required by paragraphs 
(g)(2)(ii)(A) and (B) of this AD.
    (A) Using 10X or higher power magnifying glass, visually inspect 
the yoke for any crack, seam, lap, shut, and any flaw that is open 
to the surface. If there is any crack, seam, lap,

[[Page 24053]]

shut, or flaw, before further flight, remove the yoke from service 
and replace it with an airworthy yoke, and torque each newly-
installed bolt, nut, and palnut P/N B330-19 using the torque value 
information in Appendix 1 to this AD.
    (B) If the yoke is not removed from service as a result of the 
actions required by paragraph (g)(2)(ii)(A) of this AD, perform a 
magnetic particle inspection for any crack, seam, lap, shut, and any 
flaw that is open to the surface using a method in accordance with 
FAA-approved procedures. If there is any crack, seam, lap, shut, or 
flaw, before further flight, remove the yoke from service and 
replace it with an airworthy yoke, and torque each newly-installed 
bolt, nut, and palnut P/N B330-19 using the torque value information 
in Appendix 1 to this AD.

(h) Special Flight Permit

    A one-time flight permit may be issued in accordance with 14 CFR 
21.197 and 21.199 to fly to a maintenance area to perform the 
required actions in this AD, provided there are no passengers 
onboard.

(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)(1) of this 
AD and email 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) Additional Information

    (1) For more information about this AD, contact Eric Moreland, 
Aviation Safety Engineer, FAA, 3960 Paramount Boulevard, Lakewood, 
CA 90712; phone: (562) 627-5364; email: [email protected].
    (2) For material identified in this AD that is not incorporated 
by reference, 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; website: 
robinsonheli.com.

(k) Material Incorporated by Reference

    None.

Appendix 1 to AD 2025-11-07

BILLING CODE 4910-13-C

[[Page 24054]]

[GRAPHIC] [TIFF OMITTED] TN06JN25.001


    Issued on May 29, 2025.
Steven W. Thompson,
Acting Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2025-10097 Filed 6-5-25; 8:45 am]
BILLING CODE 4910-13-P

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