Amateur-built LONG EZ accident near Lone Pine, California, June 20, 1993
On June 20, 1993 at about 9:00 pm local time, a amateur-built LONG EZ, registered N977ST, was substantially damaged in an accident near Lone Pine, California. It was a personal flight under general aviation rules (Part 91). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
the failure of the number four cylinder exhaust valve due to excessive heat exposure and lack of maintenance.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 20, 1993 · about 9:00 pm local time
- Place
- Lone Pine, California · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built LONG EZ
- Registration
- N977ST · registry record · serial 100ST
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
THE PILOT STATED THAT HE WAS IN LEVEL CRUISE AT 10,500 FEET MSL WHEN THE ENGINE SUDDENLY QUIT. HE MADE A FORCED LANDING ON OWENS DRY LAKE, WHICH WAS SOFT FROM RECENT RAINS. THE NOSE GEAR COLLAPSED AND THE AIRPLANE NOSED OVER INVERTED. POST CRASH EXAMINATION OF THE ENGINE REVEALED THAT THE EXHAUST VALVE HAD FAILED IN THE NUMBER FOUR CYLINDER. THE VALVE HEAD HAD SEPARATED FROM THE VALVE STEM. EXAMINATION OF THE VALVE SPRING AREA REVEALED OVERHEAT SIGNATURES IN THE FORM OF OIL COKING AND OXIDIZATION, AND CARBON DEPOSITS. THE NTSB METALLURGY LABORATORY FOUND THAT THE VALVE STEM WAS DEVOID OF CHROME PLATING IN THE AREA OF THE FRACTURE, WAS REDUCED IN DIAMETER, AND HAD A SIGNIFICANTLY DECREASED MATERIAL HARDNESS, ALL PRINCIPALLY DUE TO HEAT EXPOSURE. POST ACCIDENT EXAMINATION OF THE LOG BOOKS AND THE FAA OPERATING LIMITATIONS REVEALED NO RECORD OF A REQUIRED CONDITION (ANNUAL EQUIVALENT) INSPECTION SINCE THE AIRCRAFT WAS PLACED INTO SERVICE. EXAMINATION OF THE ENGINE REVEALED MANY AREAS OF SUBSTANDARD MAINTENANCE PRACTICES.
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: commercial pilot
- Ratings: single-engine land; instrument: airplane
- Flight time: 4,000 hours in all; 15 in the last 90 days
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: frt
The aircraft
- Airframe total time: 484 hours
- Last inspection: inspection type not recorded
- Maximum gross weight: 1,325 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming O-235-L2C (piston); 0 hours total
The flight
- Departed from: MMH Mammoth CA at 8:30 pm
- Destination: VNY Van Nuys CA
- Flight plan: VFR
- Runway 0
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
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.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.