Hiller UH 12D N97TH
23 August 2016 · Cokeville, Wyoming, United States · Minor injuries
Summary
On 23 August 2016 at about 13:45 local time, a Hiller UH 12D registered N97TH, operated by Wyoming Helicopters Inc DBA, was involved in an accident near Cokeville, Wyoming, United States. One person was on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.
The record
- Date
- at 13:45
- Classification
- Accident
- Location
- Cokeville, Wyoming, United States
- Coordinates
- 42.0669, -110.9469
- Aircraft
- Hiller UH 12D
- Registration
- N97TH
- Category
- Helicopter
- Year built
- 1960
- Operator
- Wyoming Helicopters Inc DBA
- Operating rule
- Part 137: Agricultural
- Purpose of flight
- Business
- Phase of flight
- Not recorded
- Route
- Cokeville → Cokeville
- Aircraft damage
- Substantial
- Weather
- VMC
- Light
- Day
- NTSB number
- CEN16LA330
People
1 person had minor injuries.
| On board | Died | Serious | Minor | Uninjured |
|---|---|---|---|---|
| 1 | 0 | 0 | 1 | 0 |
Probable cause
Failure of the control rotor cuff due to fatigue.
Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.
Read the full NTSB narrative
The commercial pilot was conducting an agricultural spray run in the helicopter when he felt a "bump" in the cyclic. The helicopter began to shake violently, and the pilot tried to conduct a forced landing; however, the skid caught on bushes and the helicopter impacted terrain. A control rotor cuff was located about 150 ft from the main wreckage. Examination of the component at the NTSB materials laboratory found a fatigue crack starting at the cuff's bolt hole and progressing until the part separated from overload. A review of maintenance records revealed that the cuff was overhauled at 988.7 hours and had accumulated 131.9 hours since overhaul. The rotor cuff was subject to an airworthiness directive (AD) which required repetitive inspections, though the investigation was unable to determine whether the AD had been complied with. The investigation also noted ambiguity with the wording used in the AD; it was unclear whether the part was subject to replacement at 225 hours total time in service, or if the 225-hour replacement was only applicable to components without known service history. The accident is consistent with an in-flight separation of the control rotor cuff due to fatigue failure.
Quoted verbatim from the NTSB record.
Other Hiller UH-12D accidents
| Date | Aircraft | Location | Operator | Outcome | Died |
|---|---|---|---|---|---|
| 17 Jul 2020 | Hiller UH 12D | Mehama, Oregon, United States | Western Helicopter Service Inc | Fatal | 1 |
| 7 Aug 2012 | Hiller UH-12D | Deer Island, Oregon, United States | Western Helicopter Services Inc | Minor injuries | - |
| 17 Mar 2011 | Hiller UH-12D | Iowa, Louisiana, United States | Williams Management | No injuries | - |
| 3 Sep 2001 | Hiller UH-12D | Lubbock, Texas, United States | Aero Management, Inc. | Minor injuries | - |
| 24 Oct 1997 | Hiller UH-12D | Farmingdale, New Jersey, United States | - | No injuries | - |
| 16 Feb 1996 | Hiller UH-12D | Carrizo Springs, Texas, United States | - | No injuries | - |
Other accidents in this area
| Date | Aircraft | Location | Operator | Outcome | Died |
|---|---|---|---|---|---|
| 7 Jul 2016 | Gulfstream American AA 5 | Cheyenne, Wyoming, United States | Tomorrows Aeronautical Museum | No injuries | - |
| 6 Oct 2016 | Piper PA18 | Hanna, Wyoming, United States | - | No injuries | - |
| 23 Dec 2016 | Lueck KITFOX 7 | Cody, Wyoming, United States | - | No injuries | - |
| 23 Oct 2016 | Cessna 182Q | Buffalo, Wyoming, United States | Garland Air LLC | Serious injuries | - |
| 5 Nov 2016 | Stamper RV-10 | Dubois, Wyoming, United States | - | Fatal | 1 |
| 13 Mar 2016 | Cessna 182A | Alpine, Wyoming, United States | - | Fatal | 4 |