Schweizer 269C accident near Piney Flats, Tennessee, May 24, 2012
On May 24, 2012 at about 10:30 pm local time, a 1988 Schweizer 269C (helicopter), registered N760DA, was substantially damaged in an accident during approach (VFR pattern final) near Piney Flats, Tennessee. It was a personal flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The mechanic’s improper maintenance of the main transmission aft pinion nut and belt drive system, which resulted in the uncoupling of the tail rotor driveshaft and the subsequent loss of helicopter control.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 24, 2012 · about 10:30 pm local time
- Place
- Piney Flats, Tennessee · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Schweizer 269C, built 1988 · all 269Cs on the register
- Registration
- N760DA · no longer on the register · serial S1326
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that, while on short final for landing, he heard a "high pitched whine" and that the helicopter's tail rotor authority subsequently degraded. He immediately initiated a full autorotation to landing. During the landing in a field with uneven terrain, the helicopter was substantially damaged. Postaccident examination revealed that, during the flight, the tail rotor driveshaft (TRDS) had become uncoupled from the drive assembly and main rotor belt transmission. The forward TRDS retention nut was found safety wired; however, it was less than hand tight. The main rotor transmission input aft pinion nut was found backed off the pinion; the nut and pieces of its fractured cotter pin were found captured in grease contained in the TRDS fitting grease cavity. The nut was intact, but it exhibited thread wear. The cotter pin was shorter and thinner than the cotter pin specified in the helicopter manufacturer's illustrated parts catalog. The grease in the aft pinion splines was discolored, caked, and dry, indicating that it had not been serviced in a long time. The main rotor transmission input pinion exhibited significant wear on the forward spline set and the aft spline set that engaged the driving spline, which was normally retained by the aft pinion nut. The aft upper H-frame bearing was displaced on the driving spline. The driving splines' interior spline teeth exhibited severe wear matching the wear on the pinion, and rotation damage was found on the spline ends. Other areas of the pinion exhibited fretting corrosion. According to the helicopter manufacturer's Handbook of Maintenance Instructions, during the 1,200-hour inspection, the mechanic was required to remove the upper pulley, inspect the pinion, and torque and safety wire the aft pinion nut during reassembly. The mechanic who performed the 1,200-hour inspection (and others) stated that, during the inspection, he had "never gotten into" the drive assembly, had not checked the torque on the aft pinion nut, and had not inspected the cotter pin.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Flight control sys malf/fail during approach (VFR pattern final) defining event
- Autorotation Off-field or emergency landing
- Autorotation Hard landing
The NTSB's findings
- cause Aircraft › Aircraft propeller/rotor › Tail rotor drive system › (general) › Incorrect service/maintenance
- cause Aircraft › Aircraft propeller/rotor › Tail rotor drive system › (general) › Inadequate inspection
- cause Aircraft › Aircraft propeller/rotor › Tail rotor drive system › (general) › Damaged/degraded
- cause Aircraft › Aircraft propeller/rotor › Tail rotor drive system › (general) › Malfunction
- cause Personnel issues › Task performance › Maintenance › Scheduled/routine maintenance › Maintenance personnel
- cause Personnel issues › Task performance › Inspection › Scheduled/routine inspection › Maintenance personnel
- cause Personnel issues › Action/decision › Action › Lack of action › Maintenance personnel
Pilot
- Certificate: flight instructor, commercial pilot, private
- Ratings: single-engine land; instructor: helicopter; instrument: airplane; rotorcraft: helicopter
- Flight time: 967 hours in all; 586 in this make and model; 17 in the last 90 days; 5 in the last 30 days; 798 as pilot in command; 64 on instruments
- Last flight review: May 30, 2011
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 6,489 hours
- Last inspection: annual inspection, December 9, 2011
- Maximum gross weight: 2,050 lb
- Seats: 3
- Landing gear: fixed
- Engine: Lycoming HIO-360-D1A (piston); 2,182 hours total
- Operator: Turbinator Aviation LLC
The flight
- Departed from: 0A9 Elizabethton TN at 10:15 pm
- Destination: Piney Flats TN
- Flight plan: none
- A second pilot was aboard
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: a few clouds at 6,500 ft
- Temperature: 81°F (27°C), dew point 55°F (13°C)
- Altimeter: 29.95 inHg
- Observation at 10:53 pm from TRI, 5 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.