# NTSB ERA24LA082: Mooney M20K, N231GG, Tullahoma, TN, January 3, 2024 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: January 3, 2024, 12:26 local (18:26 UTC) - Place: Tullahoma, TN - Coordinates: 35.380125, -86.246778 - Nearby events: https://openairdocs.org/map.md?lat=35.3801&lon=-86.2468&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Unknown or undetermined](https://openairdocs.org/ntsb-events/000) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 193598 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA24LA082 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/193598/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=193598 - Page: https://openairdocs.org/ntsb/ERA24LA082 ## Probable cause A total loss of engine power for undetermined reasons. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Mooney M20K, 4 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=5870220), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute: Unknown or undetermined](https://openairdocs.org/ntsb-events/000) (defining event); cases with it: [Mooney M20K, 2 cases](https://openairdocs.org/ntsb-events/000/sequence.md?model=5870220), [All aircraft, 1,703 cases](https://openairdocs.org/ntsb-events/000/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Mooney M20K, 14 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=5870220), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Mooney M20K, 28 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=5870220), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis Shortly after takeoff, during a cruise climb about 2,000 ft above ground level, the engine suddenly lost all power without any warning. The pilot attempted to glide the airplane back to the departure airport and restart the engine; however, the engine did not restart and the airplane impacted hilly terrain about 1/2-mile before reaching the runway. The engine’s most recent overhaul was about 30 years before the accident, and it accrued about 692 hours during that time. Additionally, the airplane had not been flown for more than 2 years before the accident flight. The pilot did not purchase fuel and the age of the fuel in the airplane could not be determined. During wreckage recovery, about 16 gallons of fuel (8 gallons per side) were drained from the airplane’s fuel tanks. The fuel was blue, clear, and consistent with 100LL aviation gasoline. No visible contamination was observed. Subsequent examination of the engine did not reveal any anomalies, with the exception of an inoperative right magneto; however, that did not explain a total loss of engine power without any engine roughness. ## Factual narrative On January 3, 2024, about 1226 central standard time, a Mooney M20K, N231GG, was substantially damaged when it was involved in an accident near Tullahoma, Tennessee. The commercial pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he had recently purchased the airplane and the accident flight was his first flight in the airplane. The accident flight was also the first flight since the airplane’s most recent annual inspection, which was completed the same day. No anomalies were noted during the preflight inspection, engine start, taxi, and engine run-up. The airplane took off uneventfully from runway 36 at Tullahoma Regional Airport (THA), Tullahoma, Tennessee. The pilot made a right turn southeast for the 20-mile flight back to his home airport, Franklin Country Airport (UOS), Sewanee, Tennessee. The pilot had planned to climb to 4,500 ft mean sea level (msl) for the short flight home. About 3,200 ft msl (2,000 above ground level), the engine suddenly lost all power without any warning. At that time, the airplane was about 4 miles from THA and the pilot turned back to the airport in an attempt to glide to runway 24. He also tried to restart the engine; however, the starter motor would not rotate the propeller. The pilot was unable to glide the airplane to the runway, and it impact hilly terrain about 1/2-mile before reaching the runway. Examination of the wreckage by a Federal Aviation Administration inspector revealed that it came to rest upright. Both wings and the empennage sustained substantial damage. Review of maintenance records revealed that the engine had accumulated about 692 hours since its most recent overhaul in 1994. The engine manufacturer recommended overhaul at 1,500 hours of operation or 12 calendar years, whichever occurs first. Additionally, the airplane had not been flown during the 26-month period before the accident flight. The pilot did not purchase fuel before the accident flight and stated that the fuel onboard could have been 2 years old or older. During recovery, about 16 gallons of fuel (8 gallons per tank) were drained from the airplane’s fuel tanks. The fuel was blue, clear, and consistent with 100LL aviation gasoline. No visible contamination was observed. The engine was examined following recovery of the airplane. The top spark plugs were removed. Their electrodes were intact and light gray in color. The propeller was rotated by hand. Crankshaft, camshaft, and valvetrain continuity were confirmed to the rear accessory section of the engine and thumb compression was attained on all cylinders. The left magneto produced spark at all leads when rotated by hand. The right magneto would not produce spark when rotated by hand. It was disassembled and no anomalies were noted with the points or rotor. The fuel sump and screen were absent of debris. ## Aircraft - Registration: [N231GG](https://openairdocs.org/aircraft/N231GG), registered now, S/N 25-0171, built 1979 (OpenAirDocs) - Reported make and model: MOONEY M20K - Registry model: [Mooney M20K](https://openairdocs.org/model/mooney-m20k) (registry code 5870220) (OpenAirDocs) - Registry engine: [Continental TSIO-360 series](https://openairdocs.org/engine/continental-tsio-360-series) (registry code 17019, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 25-0171 - Year built: 1979 - Airframe hours: 2406 - Engines: Continental TSIO-360-GB-1 210 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, January 3, 2024, 0 hours before - Destination: UOS, Sewanee, TN - Airport: THA, Tullahoma Regional Airport, runway 24, 5,501 × 100 ft, concrete - Equipment: Auto-pilot ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 23; injuries: none; commercial, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, waiver time limited special; last flight review May 25, 2023; seat: left; restraint: 3-point; flight hours: 416 total, 0 in this make and model, 392 as pilot in command, 82 in the last 90 days, 23 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Lowest ceiling: none - Temperature: 39 °F, dew point 30 °F - Altimeter: 30.00 inHg - Observed at: THA, 1 nm away - METAR: METAR KTHA 031835Z AUTO 00000KT 10SM CLR 04/M01 A3007 ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20240103000259A](https://openairdocs.org/incident/20240103000259A), Jan 3, 2024: Mooney Aircraft Corp. M20K, Tullahoma, TN, Substantial damage. Shortly after departure from runway 36 at ktha, on climb out, the aircraft experienced total engine power failure around 3000 ft. pilot attempted to start… ## Docket (4 files) The files NTSB released with the investigation on January 2, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=193598. 2.8 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 13 pages, 618 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16618851&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Memoranda for the record (item 2, PDF, 2 pages, 76 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16634793&FileExtension=pdf&FileName=MFRs-Rel.pdf - Excerpts from maintenance records (item 3, PDF, 10 pages, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16631646&FileExtension=pdf&FileName=Mx%20Excerpts_Redacted-Rel.pdf - Investigation photos (item 4, PDF, 2 pages, 361 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16632342&FileExtension=pdf&FileName=Photo%20Array-Rel.pdf From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.