# AD 81-09-08: Main Rotor Blade - Type: Airworthiness directive - Status: Current - Products: Hiller UH-12D and UH-12E with STC SH177WE or SH178WE - Effective: June 25, 1981 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Rotorcraft - Amendment: 39-4137 - Registered aircraft: 128 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/CA2DC9F1F8246BB386256A4E0043AB05.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/81-09-08 ## The airworthiness directive 81-09-08 HILLER AVIATION: Amendment 39-4137. Applies to Models UH-12D, UH-12E, UH-12E4 Series Helicopters, including military Models H-23F, OH-23G, and all models converted by STC SH178WE and STC SH177WE, equipped with main rotor blades Part No. 53200-03, certified in all categories. Compliance is required as indicated, unless already accomplished. To prevent possible main rotor blade failure due to the delamination of the skin at the blade tip, accomplish the following: (a) Prior to further flight, after the effective date of this AD or receipt of the priority mail AD 81-09-08, issued April 27, 1981, whichever occurs first: (1) Remove blade tip cap and visually inspect for skin bond separation in the tip cap area, in accordance with Para. II.D of Hiller Aviation Service Bulletin No. 51-8 dated March 25, 1981. (2) If the skin bond separation is detected, replace blade with like serviceable item or repair in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Western Region. Submit data defining exact areas of delamination when requesting repair approval. (3) If no skin bond separation is detected, replace the tip cap and seal, in accordance with Para. II.F of Hiller Aviation Service Bulletin No. 51-8, dated March 25, 1981. (b) Upon the effective date or upon receipt of the priority mail AD 81-09-08, issued April 27, 1981, whichever occurs first, whenever the rotor blade tip cap is removed for whatever reason, comply with the inspection requirements and tip cap reinstallation requirements of Para. (a) of this AD prior to return to service. Special flight permits may be issued in accordance with FARs 21.197 and 21.199 to operate helicopters to a base for the accomplishment of inspections or modifications required by this AD. Alternative inspections, modifications, or other actions which provide an equivalent level of safety may be used when approved by the Chief, Engineering and ManufacturingBranch, FAA Western Region. 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. 553(a)(1). All persons affected by this directive, who have not already received these documents from the manufacturer, may obtain copies upon request to Hiller Aviation, 2075 West Scranton Avenue, Porterville, California 93275. These documents may also be examined at FAA Western Region Office, Rules Docket, Room 6W14, 15000 Aviation Boulevard, Hawthorne, California 90261 and at FAA Headquarters, Rules Docket, Room 916, 800 Independence Avenue, S.W., Washington, D.C. 20591. A historical file on this AD, which includes the incorporated material in full, is maintained by the FAA Headquarters in Washington, D.C. and the FAA Western Region Office. This amendment becomes effective June 25, 1981 to all persons, except those to whom it was made immediately effective by priority mail AD 81-09-08, issued April 27, 1981. ## Affected data sheets (2) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS 4H10](https://openairdocs.org/tcds/4H10): Siam Hiller Holdings Inc.; names 1 of 1 models: UH-12D - [TCDS 4H11](https://openairdocs.org/tcds/4H11): Siam Hiller Holdings Inc.; names 1 of 2 models: UH-12E ## 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: 128 (128 by airframe model, 0 by engine model) - Makers: Hiller 125, Hiller-Osborn 2, Hiller-Rogerson Helicopter 1 Models with the most aircraft: - [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e): 103 aircraft (airframe model) - [Hiller UH-12D](https://openairdocs.org/model/hiller-uh-12d): 22 aircraft (airframe model) - [Hiller-Osborn UH-12D](https://openairdocs.org/model/hiller-osborn-uh-12d): 2 aircraft (airframe model) - [Hiller-Rogerson Helicopter UH12E](https://openairdocs.org/model/hiller-rogerson-helicopter-uh12e): 1 aircraft (airframe model) All 5 models: https://openairdocs.org/ad/81-09-08/models.md Every aircraft: https://openairdocs.org/ad/81-09-08/aircraft.md ## Related documents - [STC SH177WE](https://openairdocs.org/stc/SH177WE): Installation of Allison 250-C20/250-C20B engine and related changes.. Siam Hiller Holdings Inc, Named in the applicability - [STC SH178WE](https://openairdocs.org/stc/SH178WE): Installation of Allison 250-C20/250-C20B engine and related changes. (UH-12E-L (4 place)). Siam Hiller Holdings Inc, Named in the applicability --- 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.