Hiller UH-12C N812WC
16 May 1999 · Grafton, Ohio, United States · No injuries
Summary
On 16 May 1999 at about 00:45 local time, a Hiller UH-12C registered N812WC was involved in an accident near Grafton, Ohio, United States. 2 people were on board and nobody was injured. 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 00:45
- Classification
- Accident
- Location
- Grafton, Ohio, United States
- Coordinates
- 41.2801, -82.0292
- Aircraft
- Hiller UH-12C
- Registration
- N812WC
- Category
- Helicopter
- Engines
- 1
- Operator
- Not recorded
- Operating rule
- Part 91: General Aviation
- Purpose of flight
- Personal
- Phase of flight
- Not recorded
- Route
- Findlay → Columbia
- Aircraft damage
- Substantial
- Weather
- VMC
- Light
- Night/Dark
- NTSB number
- NYC99LA113
People
Nobody was injured.
| On board | Died | Serious | Minor | Uninjured |
|---|---|---|---|---|
| 2 | 0 | 0 | 0 | 2 |
Probable cause
Inadequate maintenance which resulted in the failure of the mercury clutch assembly.
Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.
Read the full NTSB narrative
About 500 feet above ground level, and 10 minutes before landing, the pilot noticed a change in main rotor noise. The engine rpm increased, and rotor rpm decreased. The pilot reduced collective and increased throttle, but engine rpm continued to increase, and rotor rpm continued to decrease. The pilot entered an autorotation, the helicopter impacted a wire, and then came to rest upright. Inspection of the mercury clutch revealed a 'minor' leak from the transmission sun gear seal, but no oil was discovered on the clutch shoes. In addition, the intermediate drive shaft teeth were 'severely' worn, and three of the teeth had broken corners. The clutch shoes were worn beyond limits, and were glazed consistent with overheating. One clutch return spring was broken. The driver slots in the clutch side plates were 'severely' worn, and the driver lugs were also 'severely' worn. All the clutch attaching hardware were 'improperly' safetied, using .031 inch safety wire, and 'numerous' fasteners were safetied backwards. The clutch was a conditional item. Since the last 100 hour inspection on March 12, 1999, the helicopter flew 100 hours.
Quoted verbatim from the NTSB record.
Other Hiller UH-12C accidents
| Date | Aircraft | Location | Operator | Outcome | Died |
|---|---|---|---|---|---|
| 16 Jun 1999 | Hiller UH-12C | Delphos, Ohio, United States | - | No injuries | - |
| 24 Oct 1998 | Hiller UH-12C | Clinton, Iowa, United States | - | No injuries | - |
| 6 May 2000 | Hiller UH-12C | Metter, Georgia, United States | - | Minor injuries | - |
| 15 Apr 2000 | Hiller UH-12C | Lakeland, Florida, United States | Kenneth L. Grimes | Minor injuries | - |
| 5 Oct 1997 | Hiller UH-12C | Bennington, Vermont, United States | - | No injuries | - |
| 3 Jul 1995 | Hiller UH-12C | Rio Vista, California, United States | Whirlybirds Inc | No injuries | - |
Other accidents in this area
| Date | Aircraft | Location | Operator | Outcome | Died |
|---|---|---|---|---|---|
| 16 Sep 1999 | Piper J-3 | Brookville, Ohio, United States | - | Fatal | 1 |
| 27 Oct 1999 | Cessna 210L | Medina, Ohio, United States | - | Fatal | 2 |
| 26 Aug 1999 | Cessna 150 | Madison, Ohio, United States | - | No injuries | - |
| 22 Dec 1999 | Cessna 182P | Port Clinton, Ohio, United States | - | Serious injuries | - |
| 15 Jan 1999 | Cessna 421B | Youngstown, Ohio, United States | Hawkeye Charter Service, Inc | No injuries | - |
| 9 May 1999 | Cessna 205 | Celina, Ohio, United States | Robert J. Tangeman | Fatal | 6 |