# AD 71-21-02: Tail Fin and Tail Boom - Type: Airworthiness directive - Status: Current - Products: Bell Helicopter Textron 205A and 205A-1 - Effective: December 23, 1974 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Rotorcraft - Amendment: 39-2048 - Registered aircraft: 59 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/143D6CA0C336EF7586256E01005AD5F2.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/71-21-02 ## The airworthiness directive 71-21-02 BELL: Amendment 39-1304 as amended by Amendment 39-2048. Applies to Bell Models 205A and 205A-1 helicopters certificated in all categories equipped with tail boom assembly, part number 205-032-802-1, -3, -5, -9, or -11. Compliance required as indicated. To detect a possible fatigue crack in the vertical fin forward spar in the area of the first rivet hole above the tail fin and tail boom intersection at fuselage station 434 or fin station 70.3, accomplish the following: (a) Inspect tail booms having 600 or more hours total time in service on the effective date of this AD within 25 hours time in service therefrom, in accordance with the procedures listed in paragraph (c) unless already accomplished within the last 75 hours. (b) Inspect tail booms having less than 600 hours total time in service on the effective date of this AD before reaching 625 hours total time in service in accordance with the procedures listed in paragraph (c) unless accomplished withinthe last 75 hours. (c) Accomplish repetitive inspections in accordance with the procedures listed below at intervals of not more than 100 hours time in service from the last inspection: (1) Remove the 42 degrees gear box cover from the tail boom and open the tail rotor drive shaft cover on the vertical fin. (2) Remove and do not reinstall the one rivet in the spar cap angle at fin station 70.3 and remove the paint finish and clean the area around the rivet hole, inboard and outboard sides of spar, including radius of cap angle on the left side of the fin forward spar from fin station 69.5 to 71, using cloth and methyl ethyl ketone or equivalent. (3) Inspect the rivet hole and the clear area of the fin spar for cracks using a visual or a dye penetrant or equivalent inspection method. (4) If no cracks are found, protect the clear area of the spar and rivet hole using a clear lacquer or light film of clear grease or equivalent transparent protection. (5)If cracks are found, remove the tail boom and replace with an uncracked tail boom in accordance with the procedures in The Bell Model 205A or 205A-1 Maintenance and Overhaul Instructions before further flight. (d) Before the first flight of each day after the inspection in paragraph (c) is accomplished, conduct a check as follows: (1) Remove the 42 degrees gear box cover from the tail boom and open the tail rotor drive shaft cover on the vertical fin. (2) Visually check the rivet hole area and the clear area of the fin forward spar for cracks. (3) If cracks are found, remove the tail boom and replace with an uncracked tail boom in accordance with the procedure of The Bell Model 205A or 205A-1 Maintenance and Overhaul Instructions before further flight. (4) The above check may be performed by the pilot. NOTE: For the requirements regarding the listing of compliance and method of compliance with this airworthiness directive in the aircraft permanent maintenance record, see FAR 91.173. (e) Operators not having kept time in service records on individual tail booms should use helicopter hours time in service for the purpose of this airworthiness directive. (f) The inspections noted by this AD are no longer required when the tail fin forward spar is modified in accordance with Part 2, Bell Helicopter Company Service Bulletin No. 205A- 6 dated May 11, 1971 or Revision A dated June 14, 1971, or later approved revision or in accordance with an equivalent method approved by the Chief, Engineering and Manufacturing Branch, Flight Standards Division, Southwest Region, FAA. (g) This airworthiness directive is not applicable for tail boom assemblies P/N 205- 032-802-9, serial numbers BBBI-50026 and subsequent, P/N 205-032-802-11 serial numbers BBBI-50003 and subsequent; and fuselage assemblies P/N 205-200-010-178, serial numbers BBDN-50051 and subsequent, and serial number BBDN-00101 and subsequent serial numbers. The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to the Service Manager, Bell Helicopter Company, P. O. Box 482, Fort Worth, Texas 76101. These documents may also be examined at the Office of the Regional Counsel, Southwest Region, FAA, 4400 Blue Mound Road, Fort Worth, Texas, and at FAA Headquarters, 800 Independence Avenue, S.W., Washington, D.C. A historical file on this AD which includes the incorporated material in full is maintained by the FAA at its headquarters in Washington, D.C., and at the Southwest Regional Office in Fort Worth, Texas. Amendment 39-1304 became effective October 30, 1971. This amendment 39-2048 becomes effective December 23, 1974. ## Affected data sheets (1) (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: 205A, 205A-1 ## 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: 59 (59 by airframe model, 0 by engine model) - Makers: Bell 56, Bell/Southwest Florida Aviatio 2, Bell Helicopter Textron 1 Models with the most aircraft: - [Bell 205A-1](https://openairdocs.org/model/bell-205a-1): 56 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 3 models: https://openairdocs.org/ad/71-21-02/models.md Every aircraft: https://openairdocs.org/ad/71-21-02/aircraft.md Its text cites no advisory circulars or STCs. ## NTSB investigations that cite this AD (2) 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 SEA96FA187](https://openairdocs.org/ntsb/SEA96FA187), Aug 12, 1996: Garlick UH-1H (N97NW), Coeur D'Alene, ID, substantial damage. Probable cause: Fatigue fracture of the left forward vertical stabilizer spar, resulting in loss of the vertical stabilizer and tail rotor and subsequent loss of control. A factor was insufficient applicability (by… - [NTSB ATL96LA068](https://openairdocs.org/ntsb/ATL96LA068), Mar 21, 1996: Bell 205A-1 (N68HJ), Grove Hill, AL, substantial damage. Probable cause: fatigue failure of the vertical fin forward spar in an area that was not accessible to inspection. A factor relating to the accident was: guidance for inspection of the area (where the fatigue… --- 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.