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jbell on DSKJLSW7X2PROD with RULES

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Federal Register / Vol. 86, No. 111 / Friday, June 11, 2021 / Rules and Regulations
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 inchpounds 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 CF201935, dated October 2, 2019 Transport Canada AD
CF201935, 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 helicopter.

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Accordingly, Transport Canada AD
CF201935 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 CF2019
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.
Comments The FAA received no comments on the NPRM or on the determination of the costs.
Conclusion These helicopters have been approved by the aviation authority of Canada and are approved for operation in the United States. Pursuant to the FAAs 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 helicopters.
Related Service Information Under 1
CFR Part 51
The FAA reviewed 5051912 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 100hour 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
5051912, dated June 27, 2019. This original version of the service information contains the same procedures as 5051912 Rev A, except 5051912 Rev A corrects a torque value.

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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 SLS030
056015 to determine if the helicopter is affected by the unsafe condition, whereas the applicability of this AD is by helicopters with certain serialnumbered truss assembly P/N SLS030
056015 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 service instead.
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 this AD.
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 workhour for an estimated cost of $85.
Authority for This Rulemaking Title 49 of the United States Code specifies the FAAs 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 Agencys authority.
The FAA is issuing this rulemaking under the authority described in
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