Miller ROTORWAY EXEC 162F accident near Pacoima, California, June 25, 1999
On June 25, 1999 at about 10:43 pm local time, a Miller ROTORWAY EXEC 162F (helicopter), an amateur-built aircraft,, registered N112WM, was substantially damaged in an accident near Pacoima, California. It was a flight of an unrecorded kind under general aviation rules (Part 91). 1 person was seriously injured. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 25, 1999 · about 10:43 pm local time
- Place
- Pacoima, California
- Type
- Accident
- Injuries
- 1 person was seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Miller ROTORWAY EXEC 162F ROTORWAY E, amateur-built
- Registration
- N112WM · registry record · serial 6369
- Damage
- Substantial damage
- Flight
- Flight of an unrecorded kind · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot, commercial pilot, private
- Ratings: multi-engine land; single-engine land; instrument: airplane; rotorcraft: helicopter
- Flight time: 6,000 hours in all; 15 in this make and model; 225 in the last 90 days; 75 in the last 30 days; 1,100 as pilot in command
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 4 hours
- Last inspection: annual inspection, July 3, 1999; 3 hours since
- Maximum gross weight: 1,500 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotorway RI-162 (piston); 0 hours total
The flight
- Departed from: WHP Whiteman CA at 10:40 pm
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 180° at 11 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 79°F (26°C), dew point 55°F (13°C)
- Altimeter: 29.00 inHg
- Observation at 10:53 pm from BUR, 6 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number LAX99LA236.