Airworthiness Directives; Robinson Helicopter Company Helicopters

[Federal Register Volume 89, Number 187 (Thursday, September 26, 2024)]
[Rules and Regulations]
[Pages 78785-78791]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-21921]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2024-0237; Project Identifier AD-2023-00491-R; 
Amendment 39-22853; AD 2024-19-11]
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 adopting a new airworthiness directive (AD) for all 
Robinson Helicopter Company Model R44 and R44 II helicopters. 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. This AD requires 
visually

[[Page 78786]]

inspecting a certain part-numbered flex plate assembly (flex plate) and 
certain part-numbered yokes, including each flex plate bolt, and 
depending on the inspection results, removing an affected part from 
service and replacing an affected part with an airworthy part. This AD 
also requires removing a certain part-numbered yoke from service after 
accumulating a certain number of hours time-in-service (TIS) or a 
certain number of years, or as an alternative to removing the part from 
service, performing a 10x or higher power magnification visual 
inspection and, if needed, a magnetic particle inspection. The FAA is 
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective October 31, 2024.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2024-0237; 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.
    Related Material: For Robinson 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.

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

    After receiving a report of a failed yoke in the M/R drive system, 
the FAA issued Special Airworthiness Information Bulletin AIR-22-08, 
dated April 11, 2022 (SAIB) to remind owners and operators of any 
Robinson Helicopter Company Model R44 helicopters of the importance of 
adhering to existing inspection procedures in the applicable operating 
handbooks and maintenance manuals. According to Robinson Helicopter 
Company, the yoke had fractured due to fatigue cracking and improper 
torque at the bolt hole and the yoke cross-section. After the FAA 
issued the SAIB, Robinson Helicopter Company reported an additional 
incident on a Model R44 helicopter where the yoke was fractured and 
separated from the drive train, again due to fatigue cracks and 
improper torquing.
    Accordingly, the FAA issued a notice of proposed rulemaking (NPRM) 
to amend 14 CFR part 39 by adding an AD that would apply to all 
Robinson Helicopter Company Model R44 and R44 II helicopters. The NPRM 
published in the Federal Register on February 28, 2024 (89 FR 14596). 
In the NPRM, the FAA proposed to require visually inspecting a certain 
part-numbered flex plate for any loose fasteners, cracks, fretting, 
corrosion, wear, and to ensure that the washers are bonded to both 
sides of the flex plate arms and depending on the inspection results, 
removing the flex plate from service and replacing it with an airworthy 
flex plate.
    In the NPRM, the FAA also proposed to require visually inspecting 
certain part-numbered yokes for any cracks, corrosion, and fretting, 
and depending on the inspection results, removing the yoke from service 
and replacing it with an airworthy yoke. Additionally, the FAA proposed 
to require visually inspecting each yoke bolt for a torque stripe, 
loose fastener, loose nut, and to determine if a certain part-numbered 
nut and palnut are installed. If there are any missing torque stripes, 
loose fasteners, loose nuts, or if certain nuts or palnuts are not 
installed, the FAA proposed to require removing the associated yoke 
from service and replacing it with an airworthy yoke.
    Additionally in the NPRM, the FAA proposed to require removing from 
service certain part-numbered yokes that have accumulated more than 12 
years or 2,200 total hours TIS, whichever occurs first since first 
installation on any helicopter, and replacing them with a certain-part-
numbered yoke that has accumulated less than 2,200 total hours TIS or 
12 years, whichever occurs first since first installation on any 
helicopter. As an alternative to replacing any yoke that has 
accumulated more than 12 years or 2,200 total hours TIS since first 
installation on a helicopter, the FAA proposed to allow removing paint 
from the yoke and using 10x or higher power magnifying glass to inspect 
for any crack, seam, lap, shut, missing cadmium plating, or any flaw 
which is open to the surface, and depending on the inspection results, 
removing the yoke from service and replacing it with an airworthy yoke. 
If the yoke is not replaced as a result of the alternate inspection, 
the FAA proposed to require performing a magnetic particle inspection 
of the yoke for any crack, seam, lap, shut, or any flaw which is open 
to the surface, and depending on the inspection results, removing the 
yoke from service and replacing with an airworthy yoke.
    Finally, if the yoke is replaced as a result of the actions 
required by the NPRM, the FAA proposed to require torquing each bolt, 
nut, and palnut using the torque value information in Appendix 1 to the 
proposed AD. 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 two commenters. The following 
presents the comments received on the NPRM and the FAA's response to 
each comment.

Comment Supporting the NPRM

    One individual commenter supported the NPRM without change.

Comments Requesting Changes to the Required Actions

    Request: Robinson Helicopter Company stated the 2,200 hours TIS 
requirement to replace the affected part or to perform the magnetic 
particle inspection in the proposed AD corresponds with the engine 
overhaul, service life limit, and interval for additional maintenance. 
However, Robinson Helicopter Company stated for Model R44 Cadet 
helicopters, the hours TIS requirement to replace the affected part or 
to perform the magnetic particle inspection is a 2,400 hours TIS 
requirement because of that model's more restrictive operating 
limitations on maximum takeoff weight and engine power. Therefore, 
Robinson Helicopter Company requested the FAA increase the hours TIS 
interval for the replacement of the affected part or the magnetic 
particle inspection to 2,400 hours TIS for Model R44 Cadet helicopters 
to allow the operator to coordinate the airworthiness directive 
requirements with other mandatory maintenance requirements.
    FAA Response: The FAA partially agrees with the request. The FAA 
disagrees with revising this final rule to refer to Model R44 Cadet 
helicopters because the ``Cadet'' is not a recognized type-certificated 
model on the FAA type certificate data sheet. However, the FAA agrees 
to allow Model R44 helicopters having serial numbers (S/N) 30001 and 
subsequent (also known as ``Cadet'' helicopters) to have 2,400 hours 
TIS to replace an affected part or to perform a magnetic particle 
inspection. The FAA has revised paragraphs (g)(2) and (3) of

[[Page 78787]]

this final rule accordingly to reflect that Model R44 helicopters 
having S/Ns 30001 and subsequent, on which a yoke replacement as 
specified in this final rule was not accomplished is required to remove 
that yoke from service and replace it with an airworthy yoke, prior to 
the accumulation of 2,400 total hours TIS or within 12 years since 
first installation, whichever occurs first.
    Request: Robinson Helicopter Company stated paragraph (g)(3)(i) of 
the proposed AD requires the yoke to be replaced if there is any 
missing cadmium plating. Robinson Helicopter Company stated cadmium 
plating provides corrosion protection without complete coverage and 
also can be inadvertently removed during installation and removal of 
hardware. Robinson Helicopter Company further stated that the 
requirement to remove the yoke if there is any missing cadmium plating 
will cause the unnecessary removal of many yokes. Therefore, Robinson 
Helicopter Company requested the FAA add an exception for cadmium 
plating and the removal of the yoke from service due to cadmium 
plating.
    FAA Response: The FAA agrees and has revised this AD accordingly by 
not adopting the inspection and corrective actions associated with 
cadmium plating proposed in the NPRM.
    Request: Robinson Helicopter Company stated paragraph (g)(1)(iii) 
of the proposed AD requires ensuring that nut part number (P/N) D210-6 
and palnut P/N B330-19 are installed. Robinson stated that per type 
design, only the two bolts on the flex plate assembly have palnut P/N 
B330-19 installed. Robinson Helicopter Company stated the wording in 
the proposed AD could cause some Model R44 helicopters to replace a 
yoke unnecessarily. Robinson Helicopter Company requested the FAA 
revise paragraph (g)(1)(iii) of the final rule to only apply to bolts 
shared with the flex plate assembly. Robinson Helicopter Company 
further stated it is possible some yokes do not have nut P/N D210-6 
installed and would therefore also be subject to an unnecessary yoke 
replacement. Robinson Helicopter Company requested the FAA revise the 
wording of paragraph (g)(1)(iii) in the final rule to remove the 
reference to nut P/N D210-6.
    FAA Response: The FAA agrees with these requests and revised 
paragraph (g)(1)(iii) of this AD to clarify that the inspection area is 
only for the flex plate assembly bolts and to remove any references to 
nut P/N D210-6.

Conclusion

    The FAA reviewed the relevant data, considered any comments 
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, any 
other changes described previously, and a clarification note added to 
paragraph (g)(1)(i) of this final rule, this AD is adopted as proposed 
in the NPRM. None of the changes will increase the economic burden on 
any operator.

Related Material

    The FAA reviewed Robinson Helicopter Company R44 Maintenance Manual 
and Instructions for Continued Airworthiness, Volume 1, Chapter 2 and 
Chapter 23, dated September 2023, which specifies procedures for 
inspecting the yoke and flex plate of the M/R drive, removing paint, 
applying torque, and performing a magnetic particle inspection. This 
material also contains the information specified in Appendix 1 to this 
AD, which specifies torque values, and Figure 1 to paragraph (g)(1) of 
this AD, which depicts the areas for the flex plate inspection.

Costs of Compliance

    The FAA estimates that this AD affects 1,725 helicopters of U.S. 
registry. The FAA estimates the following costs to comply with this AD. 
Labor costs are estimated at $85 per work-hour.
    Visually inspecting a flex plate will take approximately 0.25 work-
hour for an estimated cost of $21 per helicopter and $36,225 for the 
U.S. fleet.
    Visually inspecting a yoke, including inspecting each yoke bolt, 
will take approximately 1.25 work-hours for an estimated cost of $106 
per helicopter and $182,850 for the U.S. fleet.
    Replacing a yoke will take approximately 6 work-hours and parts 
will cost approximately $890 for an estimated cost of $1,400 per 
helicopter.
    Removing paint and inspecting a yoke using 10X or higher power 
magnifying glass will take approximately 1.5 work-hours for an 
estimated cost of $128 per helicopter.
    Performing a magnetic particle inspection will take approximately 
1.5 work-hours for an estimated cost of $128 per helicopter.
    Applying torque to one bolt, nut, and palnut will take 
approximately 1 work-hour for an estimated cost of $85 per hardware 
set.
    If required, replacing a flex plate will take approximately 1 work-
hour and parts will cost approximately $1,240 for an estimated cost of 
$1,325 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.

[[Page 78788]]

Sec.  39.13  [Amended]

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

2024-19-11 Robinson Helicopter Company: Amendment 39-22853; Docket 
No. FAA-2024-0237; Project Identifier AD-2023-00491-R.

(a) Effective Date

    This airworthiness directive (AD) is effective October 31, 2024.

(b) Affected ADs

    None.

(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 subsequent 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 (flex plate) 
part number (P/N) C947-1 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 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.
    Figure 1 to Paragraph (g)(1)(i)--Flex Plate Inspection
    [GRAPHIC] [TIFF OMITTED] TR26SE24.000
    
    (ii) Visually inspect yoke P/N C907-1 or C907-2, as applicable 
to your model helicopter, 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 using the torque value information in Appendix 
1 to this AD.
    (iii) Visually inspect each flex plate bolt for a torque stripe, 
loose fastener, and a loose nut, and to ensure that palnut P/N B330-
19 is installed. If there is a missing torque stripe, loose fastener 
on any nut (can be moved by hand), or if any nut is loose (nut can 
be turned by hand), or if palnut P/N B330-19 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 using the torque value information in Appendix 
1 to this AD.
    (2) For Model R44 helicopters having serial number 0002, or 0004 
through 9999 inclusive, except not 1140, and R44 II helicopters 
having serial number 1140 or 10001 through 29999 inclusive on which 
a yoke replacement as specified in paragraph (g)(1)(ii) or (iii) of 
this AD was not accomplished: Prior to the accumulation of 2,200 
total hours TIS on any yoke P/N C907-1 or C907-2 or 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, remove that 
yoke from service and replace it with an airworthy yoke, and torque 
each newly-installed bolt, nut, and palnut using the torque value 
information in Appendix 1 to this AD.
    (3) For Model R44 helicopters having serial number 30001 and 
subsequent, on which a yoke replacement as specified in paragraph 
(g)(1)(ii) or (iii) of this AD was not accomplished: Prior to the 
accumulation of 2,400 total hours TIS on any yoke P/N C907-1 or 
C907-2 or 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, remove that yoke from service and replace it with an 
airworthy yoke, and torque each newly-installed bolt, nut, and 
palnut using the

[[Page 78789]]

torque value information in Appendix 1 to this AD.
    (4) As an alternative to removing the yoke from service as 
required by paragraph (g)(2) or (3) of this AD as applicable, remove 
yoke P/N C907-1 or C907-2, as applicable to your model helicopter, 
remove the paint on the yoke using Cee-Bee stripper A-292, without 
using a plastic media abrasive paint stripper, and accomplish 
paragraphs (g)(4)(i) and (ii) of this AD, as applicable.
    (i) Using 10X or higher power magnifying glass, visually inspect 
the yoke for any crack, seam, lap, shut, and any flaw which is open 
to the surface. 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 using the torque value information in Appendix 1 to this 
AD.
    (ii) If the yoke is not removed from service as a result of the 
actions required by paragraph (g)(4)(i) of this AD, inspect it for 
any crack, seam, lap, shut, or any flaw which is open to the surface 
by performing a magnetic particle inspection 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 with an airworthy yoke, and torque each 
newly-installed bolt, nut, and palnut 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 in order 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) 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 Eric Moreland, 
Aviation Safety Engineer, FAA, 3960 Paramount Boulevard, Lakewood, 
CA 90712; phone: (562) 627-5364; email: [email protected].

(k) Material Incorporated by Reference

    None.
    Appendix 1 to AD 2024-19-11
BILLING CODE 4910-13-P

[[Page 78790]]

[GRAPHIC] [TIFF OMITTED] TR26SE24.001



[[Page 78791]]


    Issued on September 19, 2024.
Victor Wicklund,
Deputy Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2024-21921 Filed 9-25-24; 8:45 am]
BILLING CODE 4910-13-C

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