Amateur-built LANCAIR 235 accident near Agua Caliente, California, February 1, 1991
On February 1, 1991 at about 8:30 pm local time, a amateur-built LANCAIR 235, registered N17S, was substantially damaged in an accident near Agua Caliente, California. It was a personal flight under general aviation rules (Part 91). 2 people were seriously injured. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
THE FAILURE OF THE PROPELLER BLADES DUE TO A WEAKENING OF THE WOOD STRUCTURE DUE TO ACID HYDROLYSIS. A FACTOR IN THE ACCIDENT WAS THE INADEQUATE MAINTENANCE OF THE PROPELLER ASSEMBLY BY ALLOWING EXPOSURE TO EXCESSIVE MOISTURE AND HEAT.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- February 1, 1991 · about 8:30 pm local time
- Place
- Agua Caliente, California · map
- Type
- Accident
- Injuries
- 2 people were seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built LANCAIR 235 LANCAIR 23
- Registration
- N17S · registry record · serial OJ-1988
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
THE AIRCRAFT WAS ON CLIMB OUT WHEN A LOUD BANG WAS HEARD, FOLLOWED BY AN ENGINE OVERSPEED THEN ENGINE STOPPAGE. AFTER THE FORCED LANDING, THE PILOTS FOUND THAT BOTH WOODEN PROPELLER BLADES HAD SEPARATED FROM THE STEEL HUB ASSEMBLY. THE PROPELLER HUB WAS REMOVED FROM THE ENGINE AND SENT TO THE MANUFACTURER FOR FUNCTIONAL ANALYSIS AND DISASSEMBLY UNDER THE SUPERVISION OF FAA INSPECTORS. THE MANUFACTURER STATED THAT ALL INTERNAL COMPONENTS WERE FUNCTIONAL, HOWEVER, THE CAM ADJUSTMENT FOR THE HIGH AND LOW PITCH STOP SETTINGS HAD BEEN ALTERED FROM THE FACTORY SETTINGS. THE BLADE BUTT ENDS RETAINED IN THE HUB WERE REMOVED AND SUBMITTED TO THE FOREST PRODUCTS LABORATORY OF THE US DEPARTMENT OF AGRICULTURE FOR ANALYSIS. ACCORDING TO THE LABORATORY THE WOODEN BLADES FRACTURED AND SEPARATED DUE TO A HYDROLYSIS INTERACTION BETWEEN THE WOOD AND THE ADHESIVE CAUSED BY EXCESS MOISTURE AND HEAT. THE HYDROLYSIS IS A CHEMICAL DECOMPOSITION PROCESS OF THE WOOD AND GLUE RELATIONSHIP.
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
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 1,500 hours in all; 400 in this make and model; 4,500 as pilot in command
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: unk
The aircraft
- Last inspection: inspection type not recorded, January 2, 2000
- Maximum gross weight: 1,500 lb
- Seats: 2
- Landing gear: retractable
- Engine: Lycoming O-320 (piston); 0 hours total
The flight
- Departed from: MYF San Diego CA at 7:30 pm
- Flight plan: none
- Runway 0
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 090° at 15 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 2 |
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.
Other NTSB records under N17S the same tail number, which may have belonged to a different aircraft at the time
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 LAX91LA090.