Hiller UH-12E N507HA

Summary

On 7 June 1991 at about 03:45 local time, a Hiller UH-12E registered N507HA, operated by San Joaquin Helicopters, was involved in an accident near Huron, California, United States. One person was 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.

Date

7 June 1991 at 03:45

Classification

Accident

Location

Huron, California, United States

Coordinates

36.2005, -120.0905

Aircraft

Hiller UH-12E

Registration

N507HA

Category

Helicopter

Engines

1

Operator

San Joaquin Helicopters

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Night/Bright

NTSB number

LAX91LA249

Nobody was injured.

THAT UNKNOWN PILOT(S) IMPOPERLY USED THE THROTTLE CONTROL WHICH CAUSED AN OVERSPEED CONDITION. CONTRIBUTING TO THIS ACCIDENT WAS THE CONNECTING ROD BOLT FATIGUE FAILURE.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

THE PILOT COMPLETED AN AERIAL APPLICATION FLIGHT AND WAS RETURNING TO THE LOADING AREA WHEN THE HELICOPTER SUSTAINED A TOTAL LOSS OF POWER. DURING THE SUBSEQUENT AUTOROTATION THE PILOT ATTEMPTED TO SIDESLIP THE HELICOPTER BETWEEN THE ALMOND TREES BUT WAS UNABLE TO DO SO. THE ENGINE AND SUBSEQUENT METALLURGICAL EXAMINATION DISCLOSED THE NO. 3 CYLINDER CONNECTING ROD BOLT FAILED DUE TO FATIGUE. COMPANY MAINTENANCE PERSONNEL REPORTED THAT THE FATIGUE WAS CAUSED BY CONSISTENT ENGINE OVERSPEED POWER SETTINGS BY THE PILOTS FLYING THE HELICOPTER.

Quoted verbatim from the NTSB record.