# AD 59-25-03: Wobble Plate Screws - Type: Airworthiness directive - Status: Current - Products: Hiller UH-12, UH-12A, UH-12B, UH-12C, UH-12D and UH-12E - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Rotorcraft - Registered aircraft: 221 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/1E5A659C0E5CF47E86256A38005F4826.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/59-25-03 ## The airworthiness directive 59-25-03 HILLER: Applies to Hiller UH Series Helicopters As Follows: (a) UH-12 and UH-12A - incorporating both P/N 34126 wobble plate shield and P/N 34158 forged lower cyclic scissors. (b) UH-12B and UH-12C - incorporating the P/N 34158 forged lower cyclic scissors. (c) UH-12D - all Serial Numbers. (d) UH-12E - Serials 942, 954, and 2001 through 2018. Compliance required as indicated. To prevent contact between the lower cyclic scissors and the filister head screws attaching the wobble plate shield, which can result in damage to the lower scissors and subsequent loss of cyclic control, the following inspection and rework are required. (1) Daily inspect the lower cyclic scissors P/N 34158 on all models, or P/N 34141 on Models UH-12D and UH-12E for damage due to striking the wobble plate shield attachment screws. Damaged scissors must be replaced prior to next flight. (2) Not later than January 1, 1960, replace the filister head screws attaching thewobble plate shield with AN 509-8R4 flush head screws in accordance with the procedures in Hiller Service Bulletins No. 87 or No. 2004. (3) Upon accomplished of item (2) the inspections of item (1) may be discontinued. ## Affected data sheets (4) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS 6H1](https://openairdocs.org/tcds/6H1): Siam Hiller Holdings Inc.; names 2 of 2 models: UH-12, UH-12A - [TCDS 6H2](https://openairdocs.org/tcds/6H2): Siam Hiller Holdings Inc.; names 2 of 2 models: UH-12C, UH-12B - [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: 221 (221 by airframe model, 0 by engine model) - Makers: Hiller 209, Hiller - World Helicopters 2, Hiller-Osborn 2, Hiller-Felt 1, Hiller-Heli-Cab 1, Hiller-Helicopter Rep SVC 1, Hiller-Rogerson Helicopter 1, Hiller-Stanley 1, Hiller-Tri-Plex Ind.Inc. 1, Hiller-Trident Helicopters 1 Models with the most aircraft: - [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e): 103 aircraft (airframe model) - [Hiller UH-12B](https://openairdocs.org/model/hiller-uh-12b): 35 aircraft (airframe model) - [Hiller UH-12C](https://openairdocs.org/model/hiller-uh-12c): 31 aircraft (airframe model) - [Hiller UH-12D](https://openairdocs.org/model/hiller-uh-12d): 22 aircraft (airframe model) - [Hiller UH-12A](https://openairdocs.org/model/hiller-uh-12a): 16 aircraft (airframe model) - [Hiller UH-12](https://openairdocs.org/model/hiller-uh-12): 2 aircraft (airframe model) - [Hiller - World Helicopters UH-12C](https://openairdocs.org/model/hiller-world-helicopters-uh-12c): 2 aircraft (airframe model) - [Hiller-Osborn UH-12D](https://openairdocs.org/model/hiller-osborn-uh-12d): 2 aircraft (airframe model) - [Hiller-Yehnert UH-12](https://openairdocs.org/model/hiller-yehnert-uh-12): 1 aircraft (airframe model) - [Hiller-Stanley UH-12C](https://openairdocs.org/model/hiller-stanley-uh-12c): 1 aircraft (airframe model) - [Hiller-Felt UH-12C](https://openairdocs.org/model/hiller-felt-uh-12c): 1 aircraft (airframe model) - [Hiller-Helicopter Rep SVC UH-12B](https://openairdocs.org/model/hiller-helicopter-rep-svc-uh-12b): 1 aircraft (airframe model) - [Hiller-Tri-Plex Ind.Inc. UH-12B](https://openairdocs.org/model/hiller-tri-plex-ind-inc-uh-12b): 1 aircraft (airframe model) - [Hiller-Trident Helicopters UH-12C](https://openairdocs.org/model/hiller-trident-helicopters-uh-12c): 1 aircraft (airframe model) - [Hiller-Heli-Cab UH-12B](https://openairdocs.org/model/hiller-heli-cab-uh-12b): 1 aircraft (airframe model) - [Hiller-Rogerson Helicopter UH12E](https://openairdocs.org/model/hiller-rogerson-helicopter-uh12e): 1 aircraft (airframe model) All 17 models: https://openairdocs.org/ad/59-25-03/models.md Every aircraft: https://openairdocs.org/ad/59-25-03/aircraft.md 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.