Hiller UH-12E N67064

Summary

On 24 January 1999 at about 17:00 local time, a Hiller UH-12E registered N67064 was involved in an accident near Lemoore, 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

24 January 1999 at 17:00

Classification

Accident

Location

Lemoore, California, United States

Coordinates

36.2901, -119.8205

Aircraft

Hiller UH-12E

Registration

N67064

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX99LA081

Nobody was injured.

The inadequate nature of the operator's maintenance, which failed to detect the primer and magneto discrepancies. An overly lean fuel mixture and/or magneto cross firing resulted in detonation, an ensuing connecting rod failure, and a total loss of engine power. Contributing factors were the helicopter's low altitude and the uneven, soft nature of the terrain.

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

Read the full NTSB narrative

While maneuvering during an aerial application flight at 15 feet above an alfalfa field, the pilot heard a noise emanating from the engine, and it seized. The pilot made a forced landing in the underlying soft field, and the helicopter rolled over after touching down on the uneven terrain. Maintenance records review disclosed that the helicopter's engine had operated about 482 hours since being overhauled. The engine examination revealed that the number two connecting rod was broken at its crankshaft end. Additionally, an inspection of the associated cylinder and piston revealed evidence of detonation. Similar excessive heat exposure signatures were observed with the other five piston heads. A small hole was found chaffed into the fuel primer line. Carbon deposits and burned rotor fingers were found in both magnetos.

Quoted verbatim from the NTSB record.