DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0185; Project Identifier MCAI-2020-00265-R]
RIN 2120-AA64

Airworthiness Directives; Bell Textron Canada Limited (Type
Certificate Previously Held by Bell Helicopter Textron Canada Limited)
Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for Bell Textron Canada Limited (type certificate previously held by
Bell Helicopter Textron Canada Limited) (Bell) Model 505 helicopters.
This proposed AD was prompted by the discovery of a gap between the
transmission restraint assembly aft attachment hardware lower washer
and mating airframe truss assembly (truss assembly) clevis lower lug.
This proposed AD would require inspecting the transmission restraint
aft attachment hardware installation for a gap and corrective action
depending on the inspection results. 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 May 6, 2021.

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 between 9 a.m. and
5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this NPRM, contact Bell
Textron Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J1R4;
telephone (450) 437-2862 or (800) 363-8023; fax (450) 433-0272; or at
https://www.bellcustomer.com. You may view this referenced 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-2021-0185; 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, the
Transport Canada AD, any comments received, and other information. The
street address for Docket Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Matt Fuller, AD Program Manager,
General Aviation & Rotorcraft Unit, Airworthiness Products Section,
Operational Safety Branch, FAA, 10101 Hillwood Pkwy., Fort Worth, TX
76177; telephone (817) 222-5110; email matthew.fuller@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-2021-0185; Project Identifier
MCAI-2020-00265-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
this 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 NPRM.

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 Matt
Fuller, AD Program Manager, General Aviation & Rotorcraft Unit,
Airworthiness Products Section, Operational Safety Branch, FAA, 10101
Hillwood Pkwy., Fort Worth, TX 76177; telephone (817) 222-5110; email
matthew.fuller@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

Transport Canada, which is the aviation authority for Canada, has
issued Canadian AD CF-2019-35, dated October 2, 2019, to correct an
unsafe condition for Bell Model 505 helicopters, serial numbers (S/Ns)
65011 and subsequent. Transport Canada advises of a gap between the
transmission restraint assembly aft attachment hardware lower washer
and the lower lug of the truss assembly clevis identified during
quality control activity of a helicopter in final assembly. This gap
can occur on the right-hand (RH) and left-hand (LH) sides of the truss
assembly clevis. Subsequent investigation revealed that this condition
may exist on in-service helicopters. Transport Canada advises that
excessive gapping at either of these locations will result in increased
stress when fasteners are installed and that the increased stress may
result in cracking on the clevis lower lug and subsequent failure of
one or both clevis lower lugs. Transport Canada further advises that
this condition, if not corrected, could lead to loss of pylon pitch
stiffness, excessive pylon pitch motions leading to unknown cyclic
inputs to the main rotor, and consequent loss of control of the
helicopter.

Accordingly, the Transport Canada AD requires identifying the S/N
of the installed truss assembly, and for a helicopter with an affected
truss assembly installed, performing an initial inspection of the
transmission restraint aft attachment hardware installations for a gap.
Depending on the inspection results, the Transport Canada AD requires
reducing the torque to the attachment hardware, updating records, and
repetitive inspections of the attachment hardware for wear and fretting
because of the reduced friction between the mating surfaces; reporting
findings to Bell and accomplishing corrective actions specified by
Bell; or completing the installation of the attachment hardware and updat-
ing records.

FAA's Determination

These helicopters have been approved by the aviation authority of
Canada and are approved for operation in the United States. Pursuant to
the FAA's bilateral agreement with Canada, Transport Canada, its
technical representative, has notified the FAA of the unsafe condition
described in its AD. The FAA is proposing this AD after evaluating all
known relevant information and determining that an unsafe condition is
likely to exist or develop in other helicopters of the same type
design.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Bell Alert Service Bulletin (ASB) 505-19-12,
Revision A, dated July 11, 2019 (505-19-12 Rev A). This service
information specifies procedures for an inspection of the restraint
hardware installation for the presence of a gap and if needed, reducing
the torque to the affected attachment hardware, a repetitive 100-hour
inspection of the pitch restraint attachment hardware, and repair of
fretting damage on the truss assembly clevis lower lug.

This service information 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 Service Information

The FAA also reviewed Bell ASB 505-19-12, dated June 27, 2019. This
revision of the service information contains the same procedures as
505-19-12 Rev A, except 505-19-12 Rev A corrects a torque value.

Proposed AD Requirements in This NPRM

This proposed AD would require within 100 hours time-in-service
(TIS):

Accessing and cleaning the lower attachment hardware
securing the restraint to the truss assembly, loosening the torque on
each lower nut to measure the tare, and adding a torque value of 20
inch-lbs to the measured tare of each nut and torqueing each nut to
this new total value.

Inspecting for a gap around the circumference between the
nut and the washer and between the washer and the truss assembly clevis
lower lug mounting surface of the RH and LH sides, and if there is a
gap, measuring the gap.

If there is a gap that is less than 0.003 inch (0.076 mm),
installing the hardware using the original torque value of 40 to 58
foot-pounds (55 to 78 Nm) plus tare and completing the installation of
the attachment point.

If there is a gap that is 0.003 inch (0.076 mm) to 0.020
inch (0.508 mm) inclusive, installing the hardware with a decreased
torque value limit of 20 to 60 inch-pounds (2.3 to 6.8 Nm) plus tare
and completing the installation of the attachment point. This proposed
AD would also require updating records for your helicopter to indicate
the new torque limits on one or both sides. Thereafter, within 100
hours TIS, and thereafter at intervals not to exceed 100 hours TIS,
this proposed AD would require inspecting the assembly for fretting
between washer and truss lower lug mounting surface, the security of
the pitch restraint attachment hardware to make sure it does not turn
freely, and the torque seal lacquer between the nut and the washer to
make sure the torque seal is intact on the RH and LH sides. Depending
on the inspection results, this proposed AD would require removing the
cotter pin from service and removing the nut, washer, and bolt, and
inspecting the bolt and the lower surface of the truss assembly clevis
lower lug. Depending on these inspection results, this proposed AD
would require removing the bolt from service; reworking and cleaning
the lower surface of the clevis lower lug and inspecting for any
cracks; removing the clevis lower lug from service; or applying primer
and final paint. This proposed AD would then require installing the
hardware with a decreased torque value limit of 20 to 60 inch-pounds
(2.3 to 6.8 Nm Nm) plus tare and completing the installation of the
attachment point.

If there is a gap that is more than more than 0.020 inch
(0.508 mm), removing the nut, washer, and bolt from service and
repairing or replacing the truss assembly clevis lower lug in
accordance with FAA-approved procedures.

Differences Between This Proposed AD and the Transport Canada AD

The applicability of the Transport Canada AD is by helicopter S/N
and requires identifying the S/N of the installed truss assembly P/N
SLS-030-056-015 to determine if the helicopter is affected by the
unsafe condition, whereas the applicability of this proposed AD is by
helicopters with certain serial-numbered truss assembly P/N SLS-030-
056-015 installed instead. The compliance time of the initial
inspections required by the Transport Canada AD is within 100 hours air
time or 6 months, whichever occurs first, whereas this compliance time
in this proposed AD is within 100 hours TIS instead. The Transport
Canada AD requires reporting information to Bell to obtain certain
corrective action, while this AD requires repairing or removing
affected parts from service instead.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 87 helicopters of U.S. registry. Labor costs are estimated at
$85 per work-hour. Based on these numbers, the FAA estimates the
following costs to comply with this proposed AD.

Measuring tare and inspecting for a gap between the transmission
restraint assembly aft attachment hardware lower washer and the truss
assembly would take about 1 work-hour for an estimated cost of $85 per
helicopter and $7,395 for the U.S. fleet. If required, inspecting a
pitch restraint attachment point would take about 1 work-hour for an
estimated cost of $85 per attachment point per inspection cycle.

The FAA estimates the following costs to do any necessary repairs
or replacements based on the results of the inspections:

Updating records to indicate the new torque limits would
take about 0.25 work-hour for an estimated cost of $21.

Replacing a bolt would take a minimal additional amount of
time after inspecting and the part would cost about $50.

Reworking the lower surface of the clevis lower lug would
take about 1 work-hour for an estimated cost of $85.

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 this 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 adding the following new airworthiness
directive: