MIA91FA008 · Mooney M20C
Mooney M20C · Accident: partial loss of engine power (mechanical failure) en route
From Witham Field (SUA) to Toccoa Airport - R.G. Letourneau Field (TOC)
Event
- NTSB case
- MIA91FA008
- 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
- N1389W
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Witham Field (SUA), Stuart, FLTo Toccoa Airport - R.G. Letourneau Field (TOC), Toccoa, GA
- 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 (mechanical failure)
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Tree(s)
- 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
- Ignition system, magneto › Deteriorated
- Other maintenance personnel › Maintenance, compliance with ad, not performed
- Pilot in command › Visual lookout, inadequate
Approximate · Estimated position: the centre of Kissimmee, FL, the place the record names. Not the accident site.
NTSB narrative
THE PLT RPRTD THE ENG STARTED & RAN NORMALLY BEFORE TAKEOFF. HOWEVER, DURING FLT, IT BEGAN RUNNING ROUGH. THE PLT REDUCED THE POWER SETTING WHICH INITIALLY ELIMINATED THE ENG ROUGHNESS. HE CHECKED EACH MAGNETO & NOTED NO MALFUNCTION; HOWEVER, WHILE DIVERTING TO A NEARBY ARPT, THE ENG AGAIN BEGAN RUNNING ROUGH & A SEVERE LOSS OF POWER OCCURRED. ACCORDING TO WITNESSES, THE ACFT STRUCK A PALM TREE DURING A LEFT DESCENDING TURN AT LOW ALTITUDE & CRASHED. THE ENG WAS EQUIPPED WITH BENDIX MODEL S4LN-200 SERIES MAGNETOS. DURING A BENCH CHECK BOTH MAGNETOS BEGAN MISFIRING AFTER ABOUT 15 TO 20 MIN OF OPN. DISASSEMBLY OF THE MAGNETOS REVEALED THE NONCONDUCTIVE MATERIAL IN THE COILS WAS CRACKED & WAS BEGINNING TO LIQUEFY; THIS RESULTED IN MISDIRECTION OF THE HIGH VOLTAGE SPARK. THE MAGNETOS HAD APRX 2316 HRS IN SVC. ACCORDING TO AD 73-07-04, THE COILS IN THE MAGNETOS OF THIS ACFT SHOULD HAVE BEEN REPLACED AFTER ACCUMULATING APRX 2000 HRS OF OPN. THE ACFT HAD FLOWN 11 HRS SINCE THE LAST ANNUAL INSPN.
Probable cause
MALFUNCTION OF BOTH MAGNETOS DUE TO DETERIORATION OF THE COILS, FAILURE OF MAINTENANCE PERSONNEL TO COMPLY WITH AN AIRWORTHINESS DIRECTIVE, AND FAILURE OF THE PILOT TO MAINTAIN ADEQUATE VISUAL LOOKOUT WHILE ON AN APPROACH FOR AN EMERGENCY LANDING. FACTORS RELATED TO THE ACCIDENT WERE: THE OBSTRUCTION (TREE) IN THE EMERGENCY LANDING AREA, AND DIVERSION OF THE PILOT'S ATTENTION WHILE APPROACHING TO LAND.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record MIA91FA008
- Event ID
- 20001212X24499
- Case number
- MIA91FA008
- 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: e79d6257e206cd532254623825d1fd2cf37d8f3acae561e9954e76cf4d8c9a0d; retrieved 2026-09-21T15:34:42.874Z.