Piper J3C-65 accident near Castle Rock, Colorado, August 3, 1997
On August 3, 1997 at about 4:30 pm local time, a Piper J3C-65, registered N5985V, was substantially damaged in an accident near Castle Rock, Colorado. It was a personal flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A partial loss of engine power due to a cylinder exhaust valve jammed in the open position from excessive carbon deposits. A factor was the lack of suitable terrain on which to make a forced landing.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 3, 1997 · about 4:30 pm local time
- Place
- Castle Rock, Colorado · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Piper J3C-65 · all J3C-65s on the register
- Registration
- N5985V · registry record · serial 13-640
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
While in cruise flight, engine RPMs dropped from 2,350 to 1,700, and the airplane began to descend. The pilot made a forced landing in an open, uneven field. The landing gear was sheared off and the fuselage was buckled. Postaccident examination of the engine disclosed the no. 4 cylinder exhaust valve was jammed in the open position. The valve stem and guide were coated with 'gummy black deposits.' The pilot had a similar accident on July 22, 1995 (FTW 95-L-A312). In that accident, the jammed exhaust valve was attributed to excessive carbon deposits from high octane aviation gasoline usage in a low compression engine.
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: private
- Ratings: single-engine land
- Flight time: 940 hours in all; 554 in this make and model; 22 in the last 90 days; 7 in the last 30 days; 890 as pilot in command
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: rgt
The aircraft
- Airframe total time: 4,954 hours
- Last inspection: annual inspection, December 1, 1996; 44 hours since
- Maximum gross weight: 1,220 lb
- Seats: 2
- Landing gear: fixed
- Engine: Continental C-85-F12 (piston); 0 hours total
The flight
- Departed from: APA Englewood CO at 4:00 pm
- Flight plan: not recorded
- Runway 0
Weather at the time
- Light: daylight
- Visibility: 50 statute miles
- Sky: scat at 20,000 ft
- Temperature: 77°F (25°C), dew point 57°F (14°C)
- Altimeter: 30.00 inHg
- Observation at 3:45 pm from APA, 16 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.
Other NTSB records under N5985V the same tail number, which may have belonged to a different aircraft at the time
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.