CHI08CA035 · Mooney M20E
Mooney M20E · Accident: partial loss of engine power (non-mechanical) en route
From La Porte Municipal Airport (PPO) to Springfield Robertson County Airport (M91)
Event
- NTSB case
- CHI08CA035
- 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
- Unknown
- 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 M20E
- 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
- N5912Q
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From La Porte Municipal Airport (PPO), La Porte, INTo Springfield Robertson County Airport (M91), Springfield, TN
- 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 · 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 (non-mechanical)
- 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, connecting rod bolt › Loose part/bolt/nut/clamp/etc
- Engine assembly, connecting rod cap › Separation
- Other maintenance personnel › Maintenance, overhaul, major, inadequate
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The airplane was in cruise flight at 6,500 feet when the engine began to run roughly. The pilot verified both magnetos were functioning properly, switched fuel tanks, and manipulated the throttle without any improvement in engine operation. He informed air traffic control of the loss of engine power and was subsequently cleared to land at an airport about 8 nm north of his position. The engine continued to run roughly as he maneuvered for the airport. The airplane impacted rising terrain that preceded the runway threshold. The airplane came to rest within 100 feet of the threshold. The airplane received substantial damage to the right wing and engine firewall. The nose and right main landing gear collapsed during the landing. The left main landing gear remained fully extended. Examination of the engine revealed that the number 3 cylinder had separated from the engine case. Further examination showed that the number 3 connecting rod had separated from the crankshaft. The connecting rod cap, two rod bolts, and two nuts were found separated inside the engine case. One of the rod bolts was bent and fractured approximately mid-span. One-half of this bolt remained with the rod cap. The bolt's fracture surface exhibited a cup/cone shape, consistent with an overload failure. The threaded region of this bolt was undamaged. One of the nuts had undamaged threads. The first three threads adjacent to the flat side of the remaining nut were damaged. The remaining rod bolt was intact, but the three threads from the end were damaged consistent with the damage noted on the second nut. The last engine overhaul was completed on November 19, 1972. The engine had accumulated 820 hours since that overhaul.
Probable cause
The improper installation of the connecting rod bolts during major overhaul, which resulted in the separation of the connecting rod from the crankshaft in flight. Contributing to the accident was the rising terrain encountered during touchdown and the subsequent landing gear collapse.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI08CA035
- Event ID
- 20080104X00017
- Case number
- CHI08CA035
- 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, coordinates. 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: c1634d9915b35dfd92b2f5895b628eb766d8e6c1993f5351afe257938335bd46; retrieved 2026-09-22T03:17:52.473Z.