Miller ROTORWAY EXEC 162F N112WM

Summary

On 25 June 1999 at about 22:43 local time, a Miller ROTORWAY EXEC 162F registered N112WM was involved in an accident near Pacoima, California, United States. One person was on board and one was seriously injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

25 June 1999 at 22:43

Classification

Accident

Location

Pacoima, California, United States

Coordinates

Not recorded

Aircraft

Miller ROTORWAY EXEC 162F

Registration

N112WM

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Whiteman → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX99LA236

1 person was seriously injured.

The pilot's improper valve adjustments and failure to follow the manufacturer's instructions, which resulted in a loose number 3 cylinder rocker arm and a loss of engine power.

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

Read the full NTSB narrative

The experimental helicopter experienced a loss of engine power in the takeoff initial climb, about 450 feet agl, and the pilot autorotated to a hard landing on a city street. A witness who saw the helicopter hovering before takeoff said that the engine 'missed' twice before the helicopter took off. After the helicopter took off and was about 80 to 90 feet agl, he heard the engine make a 'sputtering' or 'popping' noise. This flight was the first test flight after building the helicopter and the pilot had completed 4.3 hours of engine run-ups and hover time. Examination of the engine found that the No. 3 cylinder intake valve stem cap was damaged and the rocker arm was loose. The valve lash clearances on the other three cylinders were found to be from 0.006 to 0.022 inches greater than the manufacturer's specifications. No other damage was noted to the engine or valve train. The No. 3 cylinder intake valve stem cap was replaced and the other valve clearances set to the proper 0.004-inch specification. The engine was then installed in a test cell and performed normally during all operational tests. The RotorWay Engine Manual instructs owners to measure and adjust the valve lash, and states, 'if any adjustment is necessary at one hour, valve adjustment should be repeated hourly until the lash stabilizes.' The pilot reported that he had made a total of four adjustments during the first inspection, but after that, all measurements had been within the manufacturer's specifications.

Quoted verbatim from the NTSB record.