CircumFlightN7432F Hughes 269C accident
NTSB WPR14LA340 · 2014-08-11 · Darrington, WA
Docket — crew, injuries and powerplant
Summary
The commercial pilot was conducting a local, personal flight in the rented helicopter. The pilot reported that, while descending the helicopter from 5,000 ft and approaching 4,000 ft, he increased the collective and noticed that the engine was slowing down; he was unable to recover the engine rpm to a normal range. The helicopter continued to descend until the pilot entered an autorotation. The helicopter then impacted a tree and came to rest in a small stream. The pilot stated that he did not believe that the engine ever quit but that it did not produce enough power to continue flight. Postaccident examination of the helicopter revealed that the throttle mount bracket was hanging by the throttle cable linkage and was not secured to the servo mount studs, which would have led to the loss of throttle movement for acceleration. The operator stated that the engine had been installed in the helicopter 10 flight hours before the accident. It is likely that maintenance personnel did not properly secure the throttle mount bracket during the engine installation, which led to the loss of throttle movement and inability to control engine power.
Full narrative
On August 11, 2014, about 1130 Pacific daylight time (PDT), a Hughes 269C Helicopter, N7432F, impacted terrain following a partial loss of engine power near Darrington, Washington. The airline transport pilot was not injured; the helicopter sustained substantial damage. Snohomish Flying Service (SFS) was operating the helicopter under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The local personal flight departed Snohomish, Washington, about 0815. Visual meteorological conditions prevailed, and no flight plan had been filed.The pilot reported that during a flight in the rented helicopter he was descending out of 5,000 ft. As he approached 4,000 ft, he increased collective and noticed that the engine was slowing down; he was unable to recover the engine rpm to a normal range. The helicopter continued to descend until the pilot entered an autorotation. The helicopter impacted a tree about 30 ft high and then came to rest in a small stream.
The pilot stated he did not believe the engine ever quit, but the engine would not produce enough power to continue flight.
The helicopter was recovered on August 12, 2014, by SFS and examined by Federal Aviation Administration inspectors with assistance from SFS personnel. They found that the throttle mount bracket was hanging by the throttle cable linkage and was not secured to the servo mount studs as it should have been. This would prevent the loss of throttle movement for acceleration.
The operator stated that the engine had just been installed into the helicopter 10 flight hours prior to the accident.
Probable cause
Maintenance personnel’s failure to secure the throttle mount bracket during a recent engine installation, which resulted in the loss of throttle movement and an inability to control engine power. The National Transportation Safety Board determined the probable cause of this accident.
Circumstances
- Event type
- Accident
- Highest injury
- None
- Weather conditions
- Visual Meteorological Cond
- Light condition
- Day
- Sky condition
- NONE
- Ceiling (ft)
- 0
- Visibility (sm)
- 10
- Wind direction
- 300
- Wind speed (kt)
- 6
- Temperature (F)
- 77
- Distance from field
- 0.0
Aircraft
| Registration | Make | Model | Damage | FAR part |
|---|---|---|---|---|
| N7432F | HUGHES | 269C | SUBS | 091 |
Sequence of events
| # | Occurrence | Phase |
|---|---|---|
| 1 | Enroute-descent Loss of engine power (partial) defining | Climb |
| 2 | Autorotation Off-field or emergency landing | Descent |
| 3 | Autorotation Collision with terr/obj (non-CFIT) | Descent |