AD 2022-20-11 Airworthiness Directives; Bell Textron Canada Limited Helicopters

Models named: 429. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to Bell Textron Canada Limited Model 429 helicopters, serial numbers (S/N) 57001 and subsequent, certificated in any category.

Comply with this AD within the compliance times specified, unless already done.

(1) As of the effective date of this AD, for Model 429 helicopters S/N 57002 through 57210 inclusive and S/N 57212 and subsequent that have accumulated less than 300 total hours time-in-service (TIS), within 100 hours TIS or 6 months after accumulating 300 total hours TIS, whichever occurs first; or for Model 429 helicopters S/N 57002 through 57210 inclusive and S/N 57212 and subsequent that have replaced the TR gearbox support assembly part number (P/N) 429-034-701-101 or P/N 429-035-705-101 and the helicopter has accumulated less than 300 total hours TIS since the replacement of the TR gearbox support assembly, within 100 hours TIS or 6 months after accumulating 300 total hours TIS since the replacement, whichever occurs first: (i) Visually inspect the external surface of the TR gearbox support assembly for any rivet heads that have separated from their tail. If there are any rivet heads that have separated from their tail, before further flight, remove these rivets from service and measure any gaps between the TR gearbox support assembly and the tailboom skin by following the Accomplishment Instructions, Part I, paragraphs 9.b. through 9.d. of Bell Alert Service Bulletin 429-19-47, Revision B, dated January 27, 2021 (ASB 429-19-47 Rev B). (A) If there are no gaps or if any gap measures 0.005 in (0.127 mm) or less, before further flight, replace the rivets removed from service by paragraph (g)(1)(i) of this AD with airworthy rivets. (B) If there are any gaps that exceed 0.005 in (0.127 mm), before further flight, repair the gaps, and replace the rivets removed from service by paragraph (g)(1)(i) of this AD with airworthy rivets. This AD requires repairing any gaps in accordance with a method approved by the Manager, General Aviation & Rotorcraft Section, International Validation Branch, FAA; or Transport Canada; or Bell Textron Canada Limited's Transport Canada Design Approval Organization (DAO). If approved by the DAO, the approval must include the DAO-authorized signature. (ii) Borescope inspect or use a light source and mirror to visually inspect each rivet inside the tailboom for any missing rivet tails, any rivet tails resting at the bottom of the tailboom, and any rivet tails not resting against the tailboom skin. (A) If there are any missing rivet tails, or any rivet tails resting at the bottom of the tailboom, before further flight, remove these rivets from service, and measure any gaps between the TR gearbox support assembly and the tailboom skin by following the Accomplishment Instructions, Part I, paragraphs 9.b. through 9.d. of ASB 429-19-47 Rev B. ( 1 ) If there are no gaps or if any gap measures 0.005 in (0.127 mm) or less, before further flight, replace the rivets removed from service by paragraph (g)(1)(ii)(A) of this AD with airworthy rivets. ( 2 ) If there are any gaps that exceed 0.005 in (0.127 mm), before further flight, repair the gaps, and replace the rivets removed from service by paragraph (g)(1)(ii)(A) of this AD with airworthy rivets. This AD requires repairing any gaps in accordance with a method approved by the Manager, General Aviation & Rotorcraft Section, International Validation Branch, FAA; or Transport Canada; or Bell Textron Canada Limited's Transport Canada DAO. If approved by the DAO, the approval must include the DAO-authorized signature. (B) If there are any rivet tails not resting against the tailboom skin, before further flight, remove these rivets from service and replace them with airworthy rivets. (iii) Perform a tactile inspection of the rivets identified in Figure 1 of ASB 429-19-47 Rev B, by pulling on each rivet tail with pliers or pulling by hand. If any rivet does come out when pulled with pliers or when pulled by hand, before further flight, remove any rivet from service that comes out when pulled with pliers or when pulled by hand and replace with an airworthy rivet. (2) For Model 429 helicopters S/N 57002 through 57210 inclusive and S/N 57212 and subsequent that are not identified in paragraph (g)(1) of this AD, within 100 hours TIS or 6 months after the effective date of this AD, whichever occurs first, perform the actions as specified in paragraphs (g)(1)(i) through (iii) of this AD. (3) For Model 429 helicopters S/N 57002 through 57210 inclusive and S/N 57212 and subsequent, within 400 hours TIS or 12 months, whichever occurs first after the initial inspections required by paragraph (g)(1) or (2) of this AD, as applicable to your helicopter, and thereafter at intervals not to exceed 400 hours TIS or 12 months, whichever occurs first, accomplish the actions required by paragraphs (g)(1)(i) through (iii) of this AD. (4) For Model 429 helicopters S/N 57001 and 57211, within 400 hours TIS or 12 months after the effective date of this AD, whichever occurs first, and thereafter at intervals not to exceed 400 hours TIS or 12 months, whichever occurs first, accomplish the actions required by paragraphs (g)(1)(i) through (iii) of this AD.

This AD was prompted by reports of failed rivets between the tailboom skin and the tail rotor (TR) gearbox support assembly. The FAA is issuing this AD to detect failed rivets and rivets with inadequate grip length. The unsafe condition, if not addressed, could result in deterioration of the joint structural integrity, detachment of the TR gearbox support assembly, and loss of helicopter control.

None.