2021-26-08: Tail Rotor Drive Shaft

1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. 2. The FAA amends § 39.13 by adding the following new airworthiness directive: 2021-26-08 Bell Textron Canada Limited: Amendment 39-21867; Docket No. FAA-2021-0728; Project Identifier MCAI-2020-00656-R. (a) Effective Date This airworthiness directive (AD) is effective January 27, 2022. (b) Affected ADs None. (c) Applicability This AD applies to Bell Textron Canada Limited Model 206, 206A, 206A-1, 206B, 206B-1, 206L, 206L-1, 206L-3, and 206L-4 helicopters, certificated in any category, with nut part number (P/N) MS21042L4 or P/N MS21042L5 installed on the tail rotor drive shaft (TRDS) disc pack (Thomas) couplings. Note 1 to paragraph (c): Helicopters with an OH-58A designation are Model 206A-1 helicopters. (d) Subject Joint Aircraft Service Component (JASC) Code: 6510, Tail Rotor Drive Shaft. (e) Unsafe Condition This AD was prompted by reports of cracked or missing nuts installed on the TRDS Thomas couplings. The FAA is issuing this AD to prevent failure or loss of a nut on the TRDS Thomas couplings. The unsafe condition, if not addressed, could result in loss of the tail rotor and subsequent loss of control of the helicopter. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Required Actions (1) Within 600 hours time-in-service (TIS) after the effective date of this AD: (i) For helicopters that have not been modified by installing Supplemental Type Certificate (STC) SH2750NM: (A) Remove each nut P/N MS21042L4 installed on each TRDS Thomas coupling from service, and replace with nut P/N NAS9926-4L. The location of nut P/N NAS9926-4L is depicted in Detail A Figure 1 of Bell Alert Service Bulletin (ASB) 206-19-136, dated August 27, 2019 (ASB 206-19-136) or Bell ASB 206L-19-181, Revision A, dated August 29, 2019 (ASB 206L-19-181), as applicable to your model helicopter. (B) Apply a torque of 5.65-7.90 Nm (50-70 in lb) plus tare torque to each nut installed as required by paragraph (g)(1)(i)(A) of this AD, and apply a torque stripe using torque seal lacquer (C-049) or equivalent lacquer, as shown in Figure 2 of ASB 206-19-136 or ASB 206L-19-181, as applicable to your model helicopter. Note 2 to paragraph (g)(1)(i)(B): Torque stripes are referred to as witness marks in ASB 206-19-136 and ASB 206L-19-181. (ii) For Bell Textron Canada Limited Model 206, 206A, 206A-1, 206B, 206B-1, and 206L helicopters that have been modified by installing STC SH2750NM and Model 206L-1 and 206L-3 helicopters that have been modified by installing STC SH2750NM but have not been modified by accomplishing Bell Service Instruction BHT-206-SI-2052, Revision 1, dated October 14, 2010 (BHT-206-SI-2052): (A) Remove each nut P/N MS21042L4 installed on each TRDS Thomas coupling from service, except for nuts P/N MS21042L4 installed on the forward short TRDS Thomas coupling, and replace with nut P/N NAS9926-4L. The location of nut P/N NAS9926-4L is depicted in Detail A Figure 1 of ASB 206-19-136 or ASB 206L-19-181 as applicable to your model helicopter. (B) Remove each nut P/N MS21042L4 installed on the forward short TRDS Thomas coupling from service and replace with nut P/N 90-132L4. (C) For each nut installed as required by paragraphs (g)(1)(ii)(A) and (B) of this AD, apply a torque of 5.65-7.90 Nm (50-70 in lb) plus tare torque to each nut and apply a torque stripe using torque seal lacquer (C-049) or equivalent lacquer, as shown in Figure 2 of ASB 206-19-136 or ASB 206L-19-181, as applicable to your model helicopter. (iii) For Bell Textron Canada Limited Model 206L-1 and 206L-3 helicopters that have been modified by installing STC SH2750NM and have been modified by accomplishing BHT-206-SI-2052: (A) Remove each nut P/N MS21042L4 installed on each TRDS Thomas coupling from service, except for nuts P/N MS21042L4 installed on the forward short TRDS Thomas coupling, and replace with nut P/N NAS9926-4L. The location of nut P/N NAS9926-4L is depicted in Detail A Figure 1 of ASB 206L-19-181. (B) Remove each nut P/N MS21042L4 installed on the forward short TRDS Thomas coupling from service and replace with nut P/N 90-132L4. (C) For each nut installed as required by paragraphs (g)(1)(iii)(A) and (B) of this AD, apply a torque of 5.65-7.90 Nm (50-70 in lb) plus tare torque to each nut, and apply a torque stripe using torque seal lacquer (C-049) or equivalent lacquer, as shown in Figure 2 of ASB 206L-19-181. (iv) For Bell Textron Canada Limited Model 206L-4 helicopters that have been modified by installing STC SH2750NM: (A) Remove each nut P/N MS21042L4 installed on each TRDS Thomas coupling from service, except for nuts P/N MS21042L4 installed on the forward short TRDS Thomas coupling, and replace with nut P/N NAS9926-4L. The location of nut P/N NAS9926-4L is depicted in Detail A Figure 1 of ASB 206L-19-181. (B) Remove from service each nut P/N MS21042L5 installed on the forward short TRDS Thomas coupling and replace with nut P/N 90-132L5. (C) For each nut installed as required by paragraphs (g)(1)(iv)(A) and (B) of this AD, apply a torque of 5.65-7.90 Nm (50-70 in lb) plus tare torque to each nut, and apply a torque stripe using torque seal lacquer (C-049) or equivalent lacquer, as shown in Figure 2 of ASB 206L-19-181. (2) Within 25 hours TIS after installation of any nut P/N NAS9926-4L, P/N 90-132L4, or P/N 90-132L5, as required by paragraphs (g)(1)(i)(A), (ii)(A) and (B), (iii)(A) and (B), or (iv)(A) and (B) of this AD, apply a torque of 5.65 Nm (50 in lb) to each nut. (i) If the nut does not move, apply a torque stripe using torque seal lacquer (C-049) or equivalent lacquer, as shown in Figure 2 of ASB 206-19-136 or ASB 206L-19-181, as applicable to your model helicopter. (ii) If any nut moves, inspect each TRDS Thomas coupling and each bolt, nut, and washer for elongated holes and fretting on the fasteners. If any TRDS Thomas coupling has an elongated hole, remove the TRDS Thomas coupling from service. If any bolt, nut, or washer has any fretting, remove the affected part from service. (3) As of the effective date of this AD, do not install nut P/N MS21042L4 or MS21042L5 on any TRDS Thomas coupling. (h) Alternative Methods of Compliance (AMOCs) (1) The Manager, International Validation Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the International Validation Branch, send it to the attention of the person identified in paragraph (i)(1) of this AD. Information may be emailed to: [email protected]. (2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office. (i) Related Information (1) For more information about this AD, 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 [email protected]. (2) Bell Service Instruction BHT-206-SI-2052, Revision 1, dated October 14, 2010, which is not incorporated by reference, contains additional information about the subject of this AD. This service information is available at the contact information specified in paragraphs (j)(3) and (4) of this AD. (3) The subject of this AD is addressed in Transport Canada AD CF-2020-15, dated May 13, 2020. You may view the Transport Canada AD at https://www.regulations.gov in Docket No. FAA-2021-0728. (j) Material Incorporated by Reference (1) The Director of the Federal Register approved the incorporation by reference of the service information listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51. (2) You must use this service information as applicable to do the actions required by this AD, unless the AD specifies otherwise. (i) Bell Alert Service Bulletin 206-19-136, dated August 27, 2019. (ii) Bell Alert Service Bulletin 206L-19-181, Revision A, dated August 29, 2019. (3) For Bell service information identified in this AD, contact Bell Textron Canada Limited, 12,800 Rue de l'Avenir, Mirabel, Quebec J7J 1R4, Canada; telephone 1-450-437-2862 or 1-800-363-8023; fax 1-450-433-0272; email [email protected]; or at https://www.bellflight.com/support/contact-support. (4) You may view this 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. (5) You may view this service information that is incorporated by reference at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, email: [email protected], or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html. Issued on December 12, 2021. Ross Landes, Deputy Director for Regulatory Operations, Compliance & Airworthiness Division, Aircraft Certification Service. [FR Doc. 2021-27645 Filed 12-22-21; 8:45 am]BILLING CODE 4910-13-P