# AD 2020-19-08: Main Rotor - Type: Airworthiness directive - Status: Current - Products: Bell Textron 204B, 205A-1 and 212 - Effective: October 21, 2020 - Published: September 16, 2020, 85 FR 57671–57673 - Issued: September 9, 2020 - Issued as: Final rule - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Rotorcraft - Amendment: 39-21251 - Docket: FAA-2020-0561 (https://www.regulations.gov/docket/FAA-2020-0561) - Registered aircraft: 125 may be affected, by airframe or engine model (OpenAirDocs) - Official PDF: https://openairdocs.org/files/sha256/c2/08/c208e24f7d5a336492ae82bcf6ce9f3b67a456cae0e5b85701f113f410cbdd3d (from https://www.govinfo.gov/content/pkg/FR-2020-09-16/pdf/2020-20275.pdf) - Federal Register: https://www.federalregister.gov/documents/2020/09/16/2020-20275/airworthiness-directives-bell-textron-inc-type-certificate-previously-held-by-bell-helicopter - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/9C967B145BA6B07E862585E5004E347A.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/2020-19-08 ## Summary The FAA is adopting a new airworthiness directive (AD) for Bell Textron Inc. (Type Certificate previously held by Bell Helicopter Textron Inc.) (Bell), Model 204B, 205A-1, and 212 helicopters. This AD was prompted by reports of corrosion on main rotor hub tension-torsion strap (TT strap) assemblies. This AD requires reducing the life limit of a certain part-numbered TT strap assembly and prohibits installing this TT strap assembly on any helicopter. The FAA is issuing this AD to address the unsafe condition on these products. ## The airworthiness directive 1. The authority citation for part 39 continues to read as follows: 2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD): 2020-19-08 Bell Textron Inc. (Type Certificate Previously Held by Bell Helicopter Textron Inc.): Amendment 39-21251; Docket No. FAA-2020-0561; Product Identifier 2019-SW-019-AD. ### (a) Effective Date This AD is effective October 21, 2020. ### (b) Affected ADs None. ### (c) Applicability This AD applies to Bell Textron Inc. (Type Certificate previously held by Bell Helicopter Textron Inc.), Model 204B, 205A-1, and 212 helicopters, certificated in any category, with main rotor hub tension-torsion strap (TT strap) assembly part number (P/N) 204-012-112-005 installed. ### (d) Subject Joint Aircraft System Component (JASC) Code: 6200, Main Rotor. ### (e) Unsafe Condition This AD was prompted by reports of corrosion detected on TT strap assemblies. The FAA is issuing this AD to reduce the life limit of and subsequently remove affected TT strap assemblies from service. The unsafe condition, if not addressed, could result in failure of the TT strap assembly causing loss of a main rotor blade 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 25 hours time-in-service (TIS), determine the total hours TIS and the total months since initial installation of each TT strap assembly. (i) If the TT strap assembly has accumulated 1,200 or more total hours TIS or reached 18 or more months since initial installation on any helicopter, whichever occurs first, before further flight, remove from service the TT strap assembly. (ii) If the TT strap assembly has accumulated less than 1,200 total hours TIS and reached less than 18 months since initial installation on any helicopter, create a component history card or equivalent record establishing the new life limit of 1,200 total hours TIS or 18 months since initial installation on any helicopter, whichever occurs first. (2) After the effective date of this AD, do not install TT strap assembly P/N 204-012-112-005 on any helicopter. ### (h) Special Flight Permit Special flight permits are prohibited. ### (i) Alternative Methods of Compliance (AMOCs) (1) The Manager, DSCO 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 certification office, send it to the attention of the person identified in paragraph (j)(1). Information may be emailed to: 9-ASW-190-COS@faa.gov. (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. ### (j) Related Information (1) For more information about this AD, contact Kuethe Harmon, Safety Management Program Manager, DSCO Branch, FAA, 10101 Hillwood Pkwy., Fort Worth, TX 76177; telephone 817-222-5198; email kuethe.harmon@faa.gov. (2) For service information identified in this AD, contact Bell Textron Inc., P.O. Box 482, Fort Worth, TX 76101; telephone 817-280-3391; fax 817-280-6466; or at https://www.bellcustomer.com. 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. ## Rule preamble ### Dates This AD is effective October 21, 2020. ### Addresses For service information identified in this final rule, contact Bell Textron Inc., P.O. Box 482, Fort Worth, TX 76101; telephone 817-280-3391; fax 817-280-6466; 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. ### For further information contact Kuethe Harmon, Safety Management Program Manager, DSCO Branch, FAA, 10101 Hillwood Pkwy., Fort Worth, TX 76177; telephone 817-222-5198; email kuethe.harmon@faa.gov. ### Discussion 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 204B, 205A-1, and 212 helicopters with TT strap assembly part number (P/N) 204-012-112-005 installed. The NPRM published in the Federal Register on June 9, 2020 (85 FR 35227). The NPRM was prompted by three incidents of fatigue cracking in TT strap assembly P/N 206-010-105-3 installed on Model 206 helicopters. These TT strap assemblies have stainless steel filament windings (wires) encased in a urethane cover, which was manufactured using Caytur 21 (also known as Cature 21) as the urethane-curing accelerator. Caytur 21 contains chlorides, which are retained in the urethane cover after curing and result in premature failure of the urethane cover and subsequent corrosion and failure of the encased wires of the TT strap assemblies. As a result, Bell changed the curing accelerator in the manufacturing process. Due to manufacturing process similarities of the urethane cover, TT strap assembly P/N 204-012-112-005, which is installed on Model 204B, 205A-1, and 212 helicopters, is affected by the same unsafe condition. Accordingly, the NPRM proposed to require reducing the life limit of the TT strap assembly from 2,400 total hours time-in-service (TIS) to 1,200 total hours TIS or 18 months since initial installation on any helicopter, whichever occurs first, and creating a component history card or equivalent record. The NPRM also proposed to prohibit installing the affected TT strap assembly on any helicopter. The actions of this AD are intended to prevent the TT strap assembly from remaining in service beyond its fatigue life. This condition, if not addressed, could result in failure of a TT strap, loss of a main rotor blade, and subsequent loss of control of the helicopter. ### Comments The FAA gave the public the opportunity to participate in developing this final rule. The FAA received one comment in support of the NPRM. ### FAA's Determination The FAA has reviewed the relevant information and determined that an unsafe condition exists and is likely to exist or develop on other helicopters of these same type designs and that air safety and the public interest require adopting the AD requirements as proposed. ### Differences Between This AD and the Service Information The service information specifies replacing TT strap assemblies with less than 1,200 hours TIS no later than January 1, 1979, and replacing TT strap assemblies with more than 1,200 hours TIS no later than September 1, 1978. This AD requires reducing the life limit of the TT strap assembly to 1,200 total hours TIS or 18 months since initial installation on any helicopter, whichever occurs first, instead. This AD also prohibits installing the TT strap assembly on any helicopter after the effective date of this AD. ### Related Service Information The FAA reviewed Bell Helicopter Textron Alert Service Bulletin (ASB) No. 204-78-3 for Model 204B helicopters, ASB No. 205-78-2 for Model 205A-1 helicopters, and ASB No. 212-78-4 for Model 212 helicopters, all dated April 19, 1978. This service information specifies replacing TT strap assembly P/N 204-012-112-005 at 1,200 hours TIS but no later than January 1, 1979. For any TT strap assembly P/N 204-012-112-005 that already has accumulated 1,200 hours TIS, this service information specifies replacing it no later than September 1, 1978. ### Costs of Compliance The FAA estimates that this AD affects 143 helicopters of U.S. registry. The FAA estimates that operators may incur the following costs in order to comply with this AD. Labor costs are estimated at $85 per work-hour. Determining the total hours TIS and the total months since initial installation of each TT strap assembly takes about.5 work-hours for an estimated cost of $43 per helicopter. Replacing each TT strap assembly takes about 10 work-hours and parts cost about $9,000, for an estimated cost of $9,850 per TT strap assembly. ### 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 products identified in this rulemaking action. ### 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. ### Adoption of the Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows: ## Affected data sheets (2) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS H1SW](https://openairdocs.org/tcds/H1SW): Bell Textron Inc.; names 2 of 5 models: 204B, 205A-1 - [TCDS H4SW](https://openairdocs.org/tcds/H4SW): Bell Textron Inc.; names 1 of 4 models: 212 ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 125 (125 by airframe model, 0 by engine model) - Makers: Bell 117, Bell Helicopter Textron 6, Bell/Southwest Florida Aviatio 2 Models with the most aircraft: - [Bell 205A-1](https://openairdocs.org/model/bell-205a-1): 56 aircraft (airframe model) - [Bell 212](https://openairdocs.org/model/bell-212): 54 aircraft (airframe model) - [Bell 204-B](https://openairdocs.org/model/bell-204-b): 7 aircraft (airframe model) - [Bell Helicopter Textron 212](https://openairdocs.org/model/bell-helicopter-textron-212): 5 aircraft (airframe model) - [Bell/Southwest Florida Aviatio 205 A1](https://openairdocs.org/model/bell-southwest-florida-aviatio-205-a1): 2 aircraft (airframe model) - [Bell Helicopter Textron 205A-1](https://openairdocs.org/model/bell-helicopter-textron-205a-1): 1 aircraft (airframe model) All 6 models: https://openairdocs.org/ad/2020-19-08/models.md Every aircraft: https://openairdocs.org/ad/2020-19-08/aircraft.md ## Related documents - [Proposed rule FAA-2020-0561](https://openairdocs.org/proposed/FAA-2020-0561): Notice of proposed rulemaking (NPRM), published Jun 9, 2020 Its text cites no advisory circulars or STCs. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.