# NTSB ERA25LA222: Dehavilland DHC-6 Twin Otter, N166DH, Tullahoma, TN, June 8, 2025 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Class 3 · Limited · Preliminary report - Date: June 8, 2025, 12:20 local (17:20 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: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Serious injuries - Injuries: 6 serious, 15 uninjured - Status: Investigation ongoing - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: TSB, FAA FSDO - NTSB case key (mKey): 200284 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA25LA222 - NTSB preliminary report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/200284/pdf - Page: https://openairdocs.org/ntsb/ERA25LA222 ## Preliminary report On June 8, 2025, about 1220 central daylight time, a DeHavilland DHC-6 Twin Otter, N166DH, was involved in an accident near Tullahoma, Tennessee. The commercial pilot and five passengers were seriously injured, and 15 passengers were not injured. The flight was being conducted as a 14 Code of Federal Regulations Part 91 skydiving flight. The pilot was attempting to take off from runway 24 at the Tullahoma Regional Airport (THA), Tullahoma, TN. The accident flight was his fourth flight in the airplane that day. The pilot stated the takeoff was normal and he raised the flaps once the airplane was clear of obstacles. When the airplane was about 500 ft above the ground, the pilot noticed asymmetrical thrust on the engines while syncing the propellers. He said, “In the following seconds, I continued trying to sync the props and was getting unusual feedback in the controls. I didn’t notice any loss of power in the gauges, but something felt a miss.” The pilot lowered the nose of the airplane and saw the altitude level off, and airspeed decrease. The pilot determined that the left engine had lost power. He initiated “engine out procedures” and turned left, back to the airport to try and land on runway 36. The pilot could not remember if he secured the left engine; however, he did remember adding flaps as per the engine-out procedures. The pilot said he tried to maintain airspeed above the single-engine minimum control speed (Vmc), but the airplane continued to descend. The pilot was unable to make it back to the airport and chose to land in a field. There were two trees in the field that he was unable to avoid, and the airplane impacted the trees. The airplane came to rest upright, but the left wing, left engine and the tail section separated from the airframe, resulting in substantial damage. The right wing and engine remained secured to the airframe. There was no postimpact fire. The airplane wreckage was recovered and taken to a secure facility for further examination. ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Dehavilland DHC-6 TWIN OTTER, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=2802606), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Takeoff: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490); cases with it: [Dehavilland DHC-6 TWIN OTTER, 1 case](https://openairdocs.org/ntsb-events/490/sequence.md?model=2802606), [All aircraft, 1,309 cases](https://openairdocs.org/ntsb-events/490/sequence.md) ## Aircraft - Registration: [N166DH](https://openairdocs.org/aircraft/N166DH), registered now, S/N 66, built 1967 (OpenAirDocs) - Reported make and model: DEHAVILLAND DHC-6 TWIN OTTER - Registry model: [Dehavilland DHC-6 TWIN OTTER](https://openairdocs.org/model/dehavilland-dhc-6-twin-otter) (registry code 2802606) (OpenAirDocs) - Registry engine: [Pratt & Whitney PT6A series](https://openairdocs.org/engine/pratt-whitney-pt6a-series) (registry code 52032, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 66 - Year built: 1967 - Airframe hours: 26616 - Damage: Substantial damage - Flight: Skydiving, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, September 10, 2024 - Airport: THA, Tullahoma Rgnl/Wm Northern Fld, runway 06/24, 5,501 × 100 ft, asphalt - Equipment: Unknown ## Weather - Conditions: Visual (VMC), Day - Wind: 270° at 14 knots - Visibility: 10 statute miles - Temperature: 81 °F, dew point 64 °F - Altimeter: 29.86 inHg - Observed at: KTHA - METAR: METAR KTHA 081735Z AUTO 27014KT 10SM FEW038 FEW044 SCT055 27/18 A2986 ## 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 20250608006759A](https://openairdocs.org/incident/20250608006759A), Jun 8, 2025: Dehavilland DHC-6 TWIN OTTER, Tullahoma, TN, Substantial damage. Skydive aircraft loaded 19 skydive passengers for the 4th load of the day. Pilot states that the aircraft had 360 lbs of fuel upon startup. Witnesses and pilot… ## Other investigations on N166DH (1) 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. - [NTSB GAA20CA021](https://openairdocs.org/ntsb/GAA20CA021), Oct 11, 2019: De Havilland DHC 6 Twin Otter (N166DH), Cedartown, GA, substantial damage. Probable cause: ***This report was modified on June 4, 2020. Please see the docket for this accident to view the original report.*** The departing pilot's failure to see and avoid the arriving airplane as it was… 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.