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Federal Register / Vol. 86, No. 111 / Friday, June 11, 2021 / Rules and Regulations 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.

c Applicability This AD applies to Bell Textron Canada Limited type certificate previously held by Bell Helicopter Textron Canada Limited Model 505 helicopters, certificated in any category, with a truss assembly part number P/N SLS030056015 with a serial number listed in Attachment A of Bell Alert Service Bulletin ASB 5051912, Revision A, dated July 11, 2019 ASB 5051912 Rev A.

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.

e Unsafe Condition The FAA is issuing this AD to address a gap between the transmission restraint assembly aft attachment hardware lower washer and the right-hand RH and left-hand LH mating airframe truss assembly truss assembly clevis lower lug. The unsafe condition, if not addressed, could result in increased stress, cracking and failure of one or both of the clevis lower lugs, and subsequent loss of pylon pitch stiffness, excessive pylon pitch motions leading to unknown cyclic inputs to the main rotor, and loss of control of the helicopter.

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 39AIRWORTHINESS
DIRECTIVES
1. The authority citation for part 39
continues to read as follows:

Authority: 49 U.S.C. 106g, 40113, 44701.
39.13

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

jbell on DSKJLSW7X2PROD with RULES

20211119 Bell Textron Canada Limited Type Certificate Previously Held by Bell Helicopter Textron Canada Limited:
Amendment 3921581; Docket No.
FAA20210185; Project Identifier MCAI202000265R.
a Effective Date This airworthiness directive AD is effective July 16, 2021.
b Affected ADs None.

VerDate Sep<11>2014

17:30 Jun 10, 2021

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d Subject Joint Aircraft System Component JASC
Code 5310, Fuselage Main, Structure.

f Compliance Comply with this AD within the compliance times specified, unless already done.
g Required Actions Within 100 hours time-in-service TIS
after the effective date of this AD, access the transmission restraint assembly and:
1 Remove the safety pin at each lower nut location of the aft bolts securing the restraint to the truss assembly. Use solvent C304 to remove the corrosion preventive compound on each nut and washer located under the RH
and LH truss assembly clevis lower lug.
2 Loosen the torque on each lower nut while holding the bolt with a wrench until the washer turns freely while sitting on top of the nut.
3 Measure and record the tare of each nut.
For purposes of this AD, tare is the torque required to overcome the internal friction between a self-locking nut and bolt as the nut is being turned on the bolt, but before the nut contacts the washer. Add a torque value of 20 inch-lbs to the measured tare of each nut and torque each nut to this new total value.
4 Inspect 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 as illustrated in Figure 1 of ASB 5051912 Rev A 2 sheets.
If there is a gap, measure the gap.
i If there is a gap that is less than 0.003
inch 0.076 mm, before further flight, install the hardware using the original torque value of 40 to 58 foot-pounds 55 to 78 Nm plus tare. Do not exceed the limit specified in this paragraph plus tare. Install a cotter pin and apply corrosion preventive compound C
101 and torque seal lacquer C049 between the nut, washer, and lower surface of the truss assembly clevis.
ii If there is a gap that is 0.003 inch 0.076
mm to 0.020 inch 0.508 mm inclusive,
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before further flight, install the hardware with a decreased torque value limit of 20 to 60 inch-pounds 2.3 to 6.8 Nm plus tare. Do not exceed the limit specified in this paragraph plus tare. Install a cotter pin. You may install an additional washer P/N
NAS1149E0863P before torqueing and installing the cotter pin while not exceeding the maximum limit of 60 inch-lbs plus tare.
Apply corrosion preventive compound C
101 and torque seal lacquer C049 between the nut, washer, and lower surface of the truss assembly clevis. Update records for your helicopter to indicate the new torque limits on one or both sides.
A Within 100 hours TIS after performing paragraph g4ii of this AD, and thereafter at intervals not to exceed 100 hours TIS, inspect the assembly for fretting between the washer and truss lower lug mounting surface, inspect the security of the pitch restraint attachment hardware to make sure it does not turn freely, and inspect the torque seal lacquer between the nut and the washer to make sure the torque seal is intact on the RH
and LH sides.
B If there is any fretting, the pitch restraint attachment hardware turns freely, or a torque seal is broken, remove the cotter pin from service and remove the nut, washer, and bolt. Inspect the bolt for damage and the lower surface of the truss assembly clevis lower lug for fretting damage.
1 If the bolt has damage, remove the bolt from service.
2 If the lower surface of the truss assembly clevis lower lug has fretting damage within allowable repair limits, use 400 grit sandpaper C423 and rework fretting damage smooth with adjacent surfaces, while removing minimum material. Do not exceed .010 inch 0.254 mm deep total cumulative amount of material to be removed from the cleviss lower lugs compared to adjacent original surfaces after rework. Clean with acetone C316 and let dry. With the acetone dry, visually inspect the clevis lower lug for any cracks.
i If there is a crack within allowable repair limits, repair in accordance with FAAapproved procedures. If there is a crack that meets or exceeds allowable repair limits, remove the truss assembly clevis lower lug from service.
ii If there is not a crack, apply primer C
204 to the reworked surface and let dry.
With the primer dry, apply final paint polyurethane topcoat color No. 16492 to the reworked surface.
3 If the lower surface of the truss assembly clevis lower lug has fretting damage that exceeds allowable repair limits, before further flight, remove the truss assembly clevis lower lug from service.
C Install a nut, washer, and bolt with a decreased torque value limit of 20 to 60 inchpounds 2.3 to 6.8 Nm plus tare. Do not exceed the limit specified in this paragraph plus tare. Install a cotter pin. You may install an additional washer P/N NAS1149E0863P
before torqueing and installing the cotter pin while not exceeding the maximum limit of 60
inch-lbs plus tare. Apply corrosion preventive compound C101 and torque seal lacquer C049 between the nut, washer, and lower surface of the truss assembly clevis.

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