ASN Wikibase Occurrence # 30539
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information.
If you feel this information is incomplete or incorrect, you can submit corrected information.
| Date: | Saturday 15 May 1999 |
| Time: | 20:45 LT |
| Type: |  Hiller UH-12C |
| Owner/operator: | William Asad |
| Registration: | N812WC |
| MSN: | 1038 |
| Total airframe hrs: | 7860 hours |
| Engine model: | Franklin 6V-335-B |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | near Grafton, OH -
 United States of America
|
| Phase: | En route |
| Nature: | Private |
| Departure airport: | Findlay, OH (NONE) |
| Columbia, OH (4G8) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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.
Probable Cause: Inadequate maintenance which resulted in the failure of the mercury clutch assembly.
Accident investigation:
 |
|
Sources:
NTSB NYC99LA113
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 27-Sep-2008 01:00 | ASN archive | Added |
| 28-Dec-2008 13:18 | harro | Updated |
| 26-Nov-2017 15:15 | ASN Update Bot | Updated [Time, Operator, Nature, Departure airport, Destination airport, Source, Narrative] |
| 08-Apr-2024 06:06 | ASN Update Bot | Updated [Time, Operator, Other fatalities, Phase, Departure airport, Source, Narrative, Category, Accident report] |
Corrections or additions? ... Edit this accident description
The Aviation Safety Network is an exclusive service provided by:
Quick Links:
| ASN Home | Send Correction / Feedback |
| FSF Home | Disclaimer | Copyright |
| Contact Us | Privacy Policy |
| Press / Media |
CONNECT WITH US:
©2024 Flight Safety Foundation