# Accident 20250608006759A: Dehavilland DHC-6 TWIN OTTER, Tullahoma, TN, June 8, 2025 - Type: FAA accident report (Accident/Incident Data System), as reported - Date: June 8, 2025, 11:43 local time - Place: Tullahoma, TN - Airport: Tullahoma Regional Airport/Wm Norther - Damage: Substantial damage - Phase of flight: Takeoff: Climb Out - Operating rules: General operating rules (Part 91) - Location: 35.3801° N, 86.2468° W: From the FAA - Nearby events: https://openairdocs.org/map.md?lat=35.3801&lon=-86.2468&mi=10 - Aircraft: N166DH, registered now (https://openairdocs.org/aircraft/N166DH) (OpenAirDocs) - Registry model: Dehavilland DHC-6 TWIN OTTER (registry code 2802606, https://openairdocs.org/model/dehavilland-dhc-6-twin-otter) (OpenAirDocs) - Registry engine: Pratt & Whitney PT6A series (registry code 52032, https://openairdocs.org/engine/pratt-whitney-pt6a-series) (OpenAirDocs) - Reported make and model: DEHAVILLAND DHC-6 TWIN OTTER - Reported engine: P&W CANADA PT6A - People aboard: 20 - Fatal injuries: 0 - Other injuries: 5 - Pilot certificates: Commercial pilot - Pilot flight hours: 757 total, 82 in this make and model, 95 in the last 90 days - NTSB investigation: [NTSB ERA25LA222](https://openairdocs.org/ntsb/ERA25LA222) (OpenAirDocs) - FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/) - Page: https://openairdocs.org/incident/20250608006759A ## Narrative As the FAA filed it, in capitals; the FAA replaces private details with ^PRIVACY DATA OMITTED^. 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 STATED THAT LOADING, TAXI, AND INITIAL TAKEOFF VIA RUNWAY 24 WAS UNEVENTFUL. AT APPROX. 500' AGL, WITNESSES STATED THEY HEARD AN ABNORMAL CHANGE IN ENGINE NOISE AS IF THEY WEREN'T SYNCED. THE PILOT STATED THAT AFTER TAKEOFF, CLEAR OF OBJECTS, HE RAISED THE FLAPS. AND THEN STARTED TO SYNC THE PROPS, WHICH IS WHEN HE FIRST NOTICED ASYMMETRICAL THRUST. IN THE FOLLOWING SECONDS, HE CONTINUED TRYING TO SYNC THE PROPS AND WAS GETTING UNUSUAL FEEDBACK IN THE CONTROLS. HE DIDN’T NOTICE ANY LOSS OF POWER IN THE GAUGES. HE LATER STATED THAT HE BELIEVES THAT THE ENGINE WAS SURGING DUE TO LOW FUEL. HE LOWERED THE NOSE, AND SAW THE ALTITUDE HAD LEVELED OFF, SPEED WAS STILL DECREASING AND HE BEGAN HIS LEFT ENGINE OUT EMERGENCY PROCEDURES. HE ALSO BEGAN TURNING LEFT (TOWARDS THE FAILING/FAILED ENGINE) TOWARDS THE AIRPORT HOPING TO COME BACK TO RUNWAY 36. HE NOTED THAT HE COULD NO LONGER MAINTAIN ALTITUDE AND THE AIRCRAFT WAS DESCENDING. IN THE FOLLOWING SECONDS, HE REMEMBERS ADDING FLAPS PER THE ENGINE OUT PROCEDURE. TRYING TO MAKE IT BACK TO THE AIRFIELD WAS CAUSING THE AIRSPEED TO DECAY SO HE WAS CONTINUALLY LOWERING THE NOSE A LITTLE AT A TIME TO MAINTAIN VMC. THE PILOT STATED THAT HE USES DIGITAL VERSIONS OF THE CHECKLIST ON HIS PHONE (WHICH HE PROVIDED) BUT THAT THERE WASN’T TIME TO REFERENCE A CHECKLIST AND THAT HE PERFORMED THE EMERGENCY FROM MEMORY. OF NOTE, THE CHECKLIST PROVIDED BY THE PILOT WAS SPECIFIC TO AN AIRCRAFT WITH A PROP AUTOFEATHER SYSTEM INSTALLED. THE AIRCRAFT IN THE ACCIDENT DID NOT HAVE A PROP AUTOFEATHER SYSTEM. THE PROCEDURES FOR ENGINE FAILURE IN FLIGHT/AIRBORNE IN THE PILOT PROVIDED CHECKLIST ARE DIFFERENT THEN BOTH THE CHECKLIST IN THE AFM AND THE CHECKLIST PROVIDED BY THE SKYDIVE BUSINESS (WHICH HAVE SIMILAR PROCEDURES). IN AN AUTOFEATHER SYSTEM THE SECOND STEP IS TO CONFIRM FLAPS AT 10 DEGREES, BUT THIS IS NOT THE CASE IN EITHER THE AFM OR BUSINESS PROVIDED CHECKLISTS. IN THE LATTER CHECKLISTS FLAP POSITION IS NOT REFERENCED IN THE IMMEDIATE STEPS. NO CHECKLIST WAS RECOVERED FROM THE AIRCRAFT. SHORTLY BEFORE LANDING, HE SAW A FIELD AHEAD THAT LOOKED TO BE THE MOST SUITABLE LANDING AREA, ALTHOUGH THERE WERE TWO TREES HE NEEDED TO GO BETWEEN. IMMEDIATELY PRECEDING LANDING, HE REALIZED THE GAP BETWEEN THE TREES WAS INSUFFICIENT TO FIT THE PLANE BETWEEN. HE HUGGED THE SIDE CLOSEST TO HIM AND REMEMBERS LANDING IN A FULLY CROSS CONTROLLED CONFIGURATION, WITH FULL RIGHT AILERON INPUT, FULL LEFT RUDDER INPUT, MAINTAINING VMC, AND A FULL NOSE UP INPUT PRIOR TO LANDING. THE LEFT WING MADE CONTACT WITH A TREE CAUSING A LOSS OF APPROX. 1/2 OF THE WING TO INCLUDE THE LEFT ENGINE. THE AIRCRAFT THEN MADE CONTACT WITH THE GROUND AND SPINNING 180 DEGREES COMING TO A FULL STOP. THERE WAS NO POST CRASH FIRE. UPON INITIAL POST ACCIDENT INSPECTION AT THE SCENE IT WAS NOTED THAT THE LEFT ENGINE, THAT HAD BECOME DETACHED FROM THE WING, DID NOT APPEAR TO BE FEATHERED. THE RIGHT ENGINE, STILL ATTACHED TO THE WING AND AIRCRAFT DID APPEAR TO BE FEATHERED. UPON POST CRASH LAYOUT INSPECTION IT WAS DETERMINED THAT THE RIGHT ENGINE FEATHERED POST IMPACT WITH THE TREE AS THE RESULT OF A DAMAGED OIL LINE THAT SHUT OFF OIL TO THE PROP CAUSING IT TO FEATHER. IN THE COCKPIT THE FUEL SELECTOR WAS IN BOTH, FLAPS WERE SET AT APPROXIMATELY 10 DEGREES, BOTH THROTTLE LEVERS WERE FULL FORWARD, THE FUEL WAS AFT AT CUTOFF. INSPECTION OF THE PROPS CONTROL FOUND THAT THE LEVERS WERE AFT, BUT NOT FEATHERED. TO FEATHER THE PROPS IT IS REQUIRED TO PUSH UP ON THE LEVERS AND THEN AFT TO GET PAST A STOP DETENT. THE PROP LEVERS WERE FORWARD OF THE DETENT. DURING THE DETAILED POST ACCIDENT AIRCRAFT INSPECTION THE FUEL TANKS, PUMPS, AND FILTERS WERE FOUND TO HAVE RESIDUAL LEVELS OF FUEL. THE FUEL BLADDERS’ INTEGRITY WAS PRESSURE TESTED AND WERE ABLE TO MAINTAIN 28 PSI FOR OVER 10 MINUTES ## The NTSB's investigation of this event (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 ERA25LA222](https://openairdocs.org/ntsb/ERA25LA222), Jun 8, 2025: Dehavilland DHC-6 Twin Otter (N166DH), Tullahoma, TN, substantial damage, investigation ongoing ## Other reports on N166DH (4) Matched to the same aircraft by N-number and date. - [Accident 20191011022052A](https://openairdocs.org/incident/20191011022052A), Oct 11, 2019: Dehavilland DHC-6 TWIN OTTER (N166DH), Cedartown, GA, Substantial damage. On Friday October 11, 2019, at approximately 7:00 p.m. eastern daylight time, a 1967 de havilland, model DHC-6 twin otter with registration N166DH sustained… - [Incident 20140420005959I](https://openairdocs.org/incident/20140420005959I), Apr 20, 2014: Dehavilland DHC-6 TWIN OTTER (N166DH), Sewell., NJ, No damage, 1 fatal. Parachutist, arkady shenker, age 49, departed aircraft N166DH, a Dehavilland DHC-6-100 on his 388 jump at 13,250 feet AGL. Type of parachute used was a SABRE2… - [Incident 20110527010179I](https://openairdocs.org/incident/20110527010179I), May 27, 2011: Dehavilland DHC-6 TWIN OTTER (N166DH), Williamstown, NJ, No damage, 1 fatal. On 5-27-11, at approximately 2020 hours, two voluntary parachutists collided at Cross Keys Airport, NJ during a parachute jump from aircraft DHC-6-100, s/n 66,… - [Incident 19920402021809I](https://openairdocs.org/incident/19920402021809I), Apr 2, 1992: Dhav DHC6TWNOTTER (N166DH), Deland, FL. Chute deployment normal. Jumper landed with wind at high speed. Landed hard and sustained injuries. From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. For accidents, the NTSB's own investigation is the fuller record. --- 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.