DEN99LA015 · Mooney M20C
Mooney M20C · Accident: partial loss of engine power (mechanical failure) en route
From Centennial Airport (APA) to La Junta Municipal Airport (LHX)
Event
- NTSB case
- DEN99LA015
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Mooney M20C
- Aircraft type
- Mooney M20
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N6405U
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Centennial Airport (APA)To La Junta Municipal Airport (LHX), La Junta, CO
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · climb to cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Partial loss of engine power (mechanical failure)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Engine assembly, camshaft › Undertorqued
- Other maintenance personnel › Maintenance, overhaul, improper
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
During climb following departure, the engine lost power. The pilot reported the emergency to the tower and attempted to return to the airport. Determining that he would be unable to make it back, he made an emergency landing in a field one and a half miles southeast of the airport. Postaccident examination of the engine revealed that the camshaft gear retaining bolts connecting the camshaft gear to the camshaft had lost torque. As a result, the lobes failed to open their respective valves, creating discontinuity to the gear train. The tread on each of the four camshaft gear bolts exhibited shiny, worn patterns. According to a Textron Lycoming engineer, loss of camshaft retaining bolt torque is indicative of the bolts being improperly torqued during the engine overhaul. According to aircraft maintenance records, the engine was overhauled on March 15, 1985, and had accumulated 833 hours since overhaul.
Probable cause
The undertorquing of the camshaft gear retaining bolts during engine overhaul by maintenance personnel. A factor was the unsuitable terrain for a forced landing.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record DEN99LA015
- Event ID
- 20001211X11245
- Case number
- DEN99LA015
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 80bb8791fe645a5c0cf6831a329abb6ef1e4131b687423f7bb1d0ca32063d584; retrieved 2026-09-21T11:19:25.862Z.