DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-0872; Project Identifier AD-2022-00431-R]
RIN 2120-AA64

Airworthiness Directives; Robinson Helicopter Company Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD)
2021-19-08, which applies to certain Robinson Helicopter Company
(Robinson) Model R44 and R44 II helicopters. AD 2021-19-08 requires
checking each tail rotor blade (blade) for any crack and removing any
cracked blade from service. AD 2021-19-08 also requires removing all
affected blades from service and prohibits installing any affected
blade on any helicopter. Since the FAA issued AD 2021-19-08, it was
determined that an additional model helicopter and additional blades
are affected by the unsafe condition. This proposed AD would require
the same actions as AD 2021-19-08 and would add certain Robinson Model
R66 helicopters to the applicability and add additional part-numbered
and serial-numbered blades to the applicability. 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 August 29,
2022.

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 https://www.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.
For service information identified in this NPRM, contact Robinson
Helicopter Company, 2901 Airport Drive, Torrance, CA 90505, United
States; phone: (310) 539-0508; email: ts1@robinsonheli.com; website:
https://robinsonheli.com/. You may view this service information at the
FAA, Office of the Regional Counsel, Southwest Region, 10101 Hillwood
Pkwy., Room 6N-321, Fort Worth, TX 76177. For information on the
availability of this material at the FAA, call (817) 222-5110.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2022-0872; 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.

FOR FURTHER INFORMATION CONTACT: James Guo, Aerospace Engineer,
Airframe Section, Los Angeles ACO Branch, Compliance & Airworthiness
Division, FAA, 3960 Paramount Blvd., Lakewood, CA 90712; telephone
(562) 627-5357; email james.guo@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-2022-0872; Project Identifier
AD-2022-00431-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
the 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
https://www.regulations.gov, including any personal information you
provide. The agency will also post a report summarizing each
substantive verbal contact received about this proposed AD.

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 James
Guo, Aerospace Engineer, Airframe Section, Los Angeles ACO Branch,
Compliance & Airworthiness Division, FAA, 3960 Paramount Blvd.,
Lakewood, CA 90712; telephone (562) 627-5357; email james.guo@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 issued AD 2021-19-08, Amendment 39-21726 (86 FR 49915,
September 7, 2021) (AD 2021-19-08), for Robinson Model R44 and R44 II
helicopters with a blade part number (P/N) C029-3 with serial number
(S/N) 9410 through 9909 inclusive, installed. AD 2021-19-08 was
prompted by reports of spanwise cracks found along the leading edge of
P/N C029-3 blades, S/N 9410 through 9909. These affected blades were
factory-installed or shipped as spares between March and December 2019.
The cracks were found at different inspection intervals ranging from
preflight inspections to 100-hour inspections. In one instance, a
cracked blade was suspected when the pilot felt
abnormal vibrations during flight; subsequent investigation determined
that the blade was cracked. The cause of the cracks was determined to
be a manufacturing defect in the properties of the blade skin that
makes the blades prone to stress corrosion cracking. This condition, if
not addressed, could result in reduced controllability and subsequent
loss of control of the helicopter. AD 2021-19-08 requires checking each
blade for any crack and removing any cracked blade from service. AD
2021-19-08 also requires removing all affected blades from service and
prohibits installing any affected blade on any helicopter. The agency
issued AD 2021-19-08 to address the unsafe condition on these products.

Actions Since AD 2021-19-08 Was Issued

Since the FAA issued AD 2021-19-08, two additional cracked blades
were discovered; these blades also exhibited stress corrosion cracking,
however they were not part of the lot of affected blades that are
included in AD 2021-19-08. These new affected blades are from a batch
of blades manufactured from a separate lot of material, and testing
determined that they are also susceptible to stress corrosion cracking
and can be installed on Robinson Model R44, R44 II, and R66
helicopters. Additionally, while AD 2021-19-08 was issued as a Final
rule; request for comments, the FAA has determined that, because the
risk model predictions for the additional helicopter model and blades
are lower, providing notice and opportunity for public comment is
appropriate.
Since the issuance of 2021-19-08, the FAA received one comment from
Robinson requesting that the FAA correct an inaccurate statement in the
background section of the preamble text. Discovery of the incident was
incorrectly described as a pilot feeling abnormal vibrations during
flight. The incident was actually discovered when the ground crew
noticed an abnormal noise during a shipboard landing.

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 designs.

Related Service Information

The FAA reviewed Robinson R44 Service Bulletin SB-108, dated June
30, 2021. This service bulletin specifies removing P/N C029-3 blades
with S/N 9410 through 9909 from service. For continued operation until
the affected blades are replaced, the service bulletin specifies a
preflight inspection to be performed by the pilot.
The FAA also reviewed Robinson R44 Service Bulletin SB-110, which
specifies removing P/N C029-3 blades with S/N 9910 through 10659 from
service and Robinson R66 Service Bulletin SB-40, which specifies
removing P/N F029-1 blades with S/N 2410 through 2589 from service.
Both of these service bulletins are dated January 6, 2022 and specify
that a preflight inspection is to be performed by the pilot for
continued operation until the affected blades are replaced.

Proposed AD Requirements in This NPRM

This proposed AD would continue to require, before further flight
and thereafter before each flight, checking each affected blade for any
crack along the leading edge of the blade. An owner/operator (pilot)
holding at least a private pilot certificate may perform this proposed
check and would have to enter compliance with the applicable paragraph
of this proposed AD in the helicopter maintenance records in accordance
with 14 CFR 43.9(a) and 91.417(a)(2)(v). A pilot may perform this check
because it involves visually checking each blade for a crack. This
action could be performed equally well by a pilot or a mechanic. This
check is an exception to the FAA's standard maintenance regulations.
This proposed AD would also continue to require, before further flight,
removing from service any cracked blade and would prohibit installing
the affected blades on any helicopter. This proposed AD would also
require, within three months after the effective date of AD 2021-19-08
or within six months after the effective date of this AD, as
applicable, removing all affected blades from service. Finally, this
proposed AD would revise the applicability by adding blades with P/N
C029-3 with S/N 9910 through 10659 inclusive to the applicability for
Robinson Model R44 and R44 II helicopters and would also expand the
applicability by adding Robinson Model R66 helicopters with blade P/N
F-029-1 with S/N 2410 through 2589 inclusive installed.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 432 helicopters of U.S. registry. The FAA estimates the
following costs to comply with this proposed AD. Labor costs are
estimated at $85 per work-hour.
Checking a blade for any crack would take about 0.25 work-hour for
an estimated cost of up to $44 per helicopter (up to two affected
blades per helicopter) and up to $19,008 for the U.S. fleet per check.
Replacing a blade would take about 3.5 work-hours and parts would cost
about $3,320 for an estimated cost of $3,618 per blade and up to
$3,125,952 for the U.S. fleet.
The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some of the costs of this
proposed AD may be covered under warranty, thereby reducing the cost
impact on affected operators.

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 that the 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.

Sec. 39.13 [Amended]

2. The FAA amends Sec. 39.13 by:

a. Removing Airworthiness Directive AD 2021-19-08, Amendment 39-21726
(86 FR 49915, September 7, 2021); and

b. Adding the following new airworthiness directive: