# AD 89-17-03: Main Rotor Masts - Type: Airworthiness directive - Status: Historical - Products: California Department of Forestry UH-1F, TH-1L, UH-1B, UH-1E, UH-1F, UH-1L, UH-1B, UH-1B, UH-1E, UH-1B, SW204 (UH-1B), SW204HP (UH-1B) and 9 more - Effective: September 5, 1989 - Superseded by: [AD 2000-08-53](https://openairdocs.org/ad/2000-08-53) - Product type: Aircraft, Rotorcraft - Amendment: 39-6251 - Docket: 88-ASW-33 - Registered aircraft: 8 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/CDF92380DD6B14D086256A4C006FF27A.0001 - DRS record last changed: August 7, 2025 - Page: https://openairdocs.org/ad/89-17-03 ## The airworthiness directive 89-17-03 CALIFORNIA DEPARTMENT OF FORESTRY; GARLICK HELICOPTERS; HAWKINS AND POWERS AVIATION, INC; HERCULES; INTERNATIONAL HELICOPTERS, INC; OREGON HELICOPTERS; PILOT PERSONNEL INTERNATIONAL, INC; SMITH HELICOPTERS; SOUTHERN AERO CORPORATION, AND WEST COAST FABRICATIONS (these helicopters were manufactured by Bell Helicopter Textron, Inc., under military contract): Amendment 39- 6251. (Airworthiness Docket No. 88-ASW-33) Applicability: Model UH-1A, UH-1B, UH-1E, UH-1F, UH-1L, and TH-1L helicopters certificated in any category. Compliance: Required as indicated, unless already accomplished. To prevent possible fatigue failure of the main rotor masts, part number (P/N) 204-011- 450-001, -005, -007, -101, -105, -109, and -113, and main rotor trunnion, (P/N) 204-011-105-001, which could result in a catastrophic failure of the main rotor system and subsequent loss of the helicopter, accomplish the following: (a) Within 10 days after the effective date of this AD,create a historical service record for the main rotor mast, (P/N) 204-011-450-001, -005, -007, -101, -105, -109, and -113, and main rotor trunnion, (P/N) 204-011-105-001, and record the hours' time in service accumulated on the main rotor mast and trunnion. If the time in service cannot be determined, enter 900 hours for each year from the date the mast and trunnion were installed. (b) For masts and trunnions with more than 14,900 hours' time in service on the effective date of this AD, remove the masts and trunnions from service within the next 100 hours' time in service. (c) For masts and trunnions with less than 14,900 hours' time in service on the effective date of this AD, remove the masts and trunnions from service at 15,000 hours' time in service. (d) An alternate means of compliance which provides an equivalent level of safety with this AD may be used when approved by the Manager, Rotorcraft Certification Office, ASW-170, Federal Aviation Administration, Fort Worth, Texas 76193-0170. This amendment (39-6251, AD 89-17-03) becomes effective on September 5, 1989. ## Affected data sheets (4) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS H7SO](https://openairdocs.org/tcds/H7SO): Overseas Aircraft Support Inc.; names 3 of 5 models: TH-1L, UH-1L, UH-1E - [TCDS H6SO](https://openairdocs.org/tcds/H6SO): Southwest Florida Aviation International; names 2 of 4 models: SW204HP (UH-1B), SW204 (UH-1B) - [TCDS H2NM](https://openairdocs.org/tcds/H2NM): California Department of Forestry; names 1 of 1 models: UH-1F - [TCDS H3SO](https://openairdocs.org/tcds/H3SO): Richards Heavylift Helo Inc.; names 1 of 4 models: UH-1A ## 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: 8 (8 by airframe model, 0 by engine model) - Makers: Southwest Florida 3, Hawkins & Powers 2, Bell-Sw Florida Avn 1, Williams Helicopter 1, Williams Helicopter Corp/Oas 1 Models with the most aircraft: - [Southwest Florida SW204](https://openairdocs.org/model/southwest-florida-sw204): 2 aircraft (airframe model) - [Hawkins & Powers UH-1B](https://openairdocs.org/model/hawkins-powers-uh-1b): 2 aircraft (airframe model) - [Bell-Sw Florida Avn UH-1B](https://openairdocs.org/model/bell-sw-florida-avn-uh-1b): 1 aircraft (airframe model) - [Southwest Florida SW204HP](https://openairdocs.org/model/southwest-florida-sw204hp): 1 aircraft (airframe model) - [Williams Helicopter UH-1B](https://openairdocs.org/model/williams-helicopter-uh-1b): 1 aircraft (airframe model) - [Williams Helicopter Corp/Oas UH-1E](https://openairdocs.org/model/williams-helicopter-corp-oas-uh-1e): 1 aircraft (airframe model) All 6 models: https://openairdocs.org/ad/89-17-03/models.md Every aircraft: https://openairdocs.org/ad/89-17-03/aircraft.md ## Related documents - [AD 2000-08-53](https://openairdocs.org/ad/2000-08-53) (historical): Main Rotor System · AST UH-1F, HH-1K, TH-1F and 32 more. Supersedes this AD Its text cites no advisory circulars or STCs. ## NTSB investigations that cite this AD (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB SEA97FA196](https://openairdocs.org/ntsb/SEA97FA196), Aug 27, 1997: Southern Aero UH-1B (N896W), Skykomish, WA, substantial damage, 1 fatal. Probable cause: A fatigue fracture in the main rotor mast, which resulted in an in flight separation of the main rotor from the helicopter. Contributing to the accident was insufficient Federal Aviation… --- 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.