DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2021-0185; Project Identifier MCAI-2020-00265-R;
Amendment 39-21581; AD 2021-11-19] RIN 2120-AA64
Airworthiness Directives; Bell Textron Canada Limited (Type
Certificate Previously Held by Bell Helicopter Textron Canada Limited)
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
SUMMARY: The FAA is adopting 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
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 AD
requires inspecting the transmission restraint aft attachment hardware
installation for a gap and corrective action depending on the
inspection results. The FAA is issuing this AD to address the unsafe
condition on these products.
DATES: This AD is effective July 16, 2021.
The Director of the Federal Register approved the incorporation by
reference of a certain document listed in this AD as of July 16, 2021.
ADDRESSES: For service information identified in this final rule,
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 the referenced
service information at the FAA, Office of the Regional Counsel,
Southwest Region, 10101 Hillwood Pkwy., Room 6N-321, Fort Worth, TX
76177. Service information that is incorporated by reference is also
available at https://www.regulations.gov by searching for and locating
Docket No. FAA-2021-0185.
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 final rule, the
Transport Canada AD, any comments received, and other information. The
street 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: 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 firstname.lastname@example.org.
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to Bell Model 505
helicopters with a truss assembly part number (P/N) SLS-030-056-015
with a serial number (S/N) listed in Attachment A of Bell Alert Service
Bulletin (ASB) 505-19-12, Revision A, dated July 11, 2019 (505-19-12
Rev A). The NPRM published in the Federal Register on March 22, 2021
(86 FR 15146). In the NPRM, the FAA proposed to require the following
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 right-hand (RH) and left-hand (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. The NPRM also
proposed to 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, the
NPRM proposed to require inspecting the assembly for fretting between the 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, the NPRM proposed to 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, the NPRM proposed to 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.
The NPRM then proposed to require 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.
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.
The NPRM was prompted by Canadian AD CF-2019-35, dated October 2,
2019 (Transport Canada AD CF-2019-35), issued by Transport Canada,
which is the aviation authority for Canada, to correct an unsafe
condition for Bell Model 505 helicopters, 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 RH and 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
Accordingly, Transport Canada AD CF-2019-35 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, Transport Canada AD CF-2019-
35 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 updating records.
The FAA received no comments on the NPRM or on the determination of
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 reviewed the relevant data 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
Related Service Information Under 1 CFR Part 51
The FAA reviewed 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
original version of the service information contains the same
procedures as 505-19-12 Rev A, except 505-19-12 Rev A corrects a torque
Differences Between This 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 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 the compliance time
in this AD is within 100 hours TIS. The Transport Canada AD requires
reporting information to Bell to obtain certain corrective action,
while this AD requires repairing or removing affected parts from
Costs of Compliance
The FAA estimates that this AD affects 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
Measuring tare and inspecting for a gap between the transmission
restraint assembly aft attachment hardware lower washer and the truss
assembly will 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 will 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 will
take about 0.25 work-hour for an estimated cost of $21.
Replacing a bolt will take a minimal additional amount of
time after inspecting and the part will cost about $50.
Reworking the lower surface of the clevis lower lug will
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 helicopters identified in this rulemaking action.
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
Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 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