Piper PA-25-235 accident near Twisp, Washington, June 20, 2021
On June 20, 2021 at about 7:10 pm local time, a 1964 Piper PA-25-235, registered N6917Z, was substantially damaged in an accident during landing near Twisp, Washington (Twisp Muni airport). It was a glider-towing flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
An in-flight separation of the control stick from the torque tube assembly, which resulted in a loss of directional control during the landing roll and subsequent on-ground collision.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 20, 2021 · about 7:10 pm local time
- Place
- Twisp, Washington · Twisp Muni · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Piper PA-25-235, built 1964 · all PA-25-235s on the register
- Registration
- N6917Z · no longer on the register · serial 25-2660
- Damage
- Substantial damage
- Flight
- Glider-towing flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot in the tailwheel-equipped airplane reported that, during the sixth flight of a glider tow operation, the control stick felt as though it had “some play” with regard to the ailerons. The control stick moved about four inches laterally before a corresponding movement of the ailerons could be observed. He landed the airplane, performed a flight control check and noticed a “little slack” between the control stick inputs and subsequent aileron movement. He determined that the control stick felt secure and took off on his seventh tow flight. During the climb out, the response to his control stick inputs diminished. The airplane encountered turbulence and the control stick separated from the torque tube assembly. He maintained control of the airplane by using trim, rudder control and throttle variations. The airplane subsequently landed on the grass surface to the right of the runway. During a firm landing, the airplane veered right, and the right wing collided with a berm. The airplane sustained substantial damage to the leading-edge of the right wing. A subsequent examination of the airplane’s flight controls, revealed that the bolt which secured the control stick to the torque tube assembly had backed out. The castellated nut and cotter pin which secured the bolt were not located.
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 landing defining event
The NTSB's findings
- Aircraft › Aircraft systems › Flight control system › Control column section › Malfunction
- Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Directional control › Not attained/maintained
- Aircraft › Fluids/misc hardware › Misc hardware › Fasteners › Not specified
Pilot
- Certificate: airline transport pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 15,077 hours in all; 516.9 in this make and model; 34.5 in the last 90 days; 27 in the last 30 days; 3,534 on instruments
- Last flight review: May 19, 2021
- Medical certificate: None (with waivers/limitations)
- Seat: sngl
- Injury: minor injuries
The aircraft
- Airframe total time: 7,278.8 hours
- Last inspection: annual inspection, March 11, 2021
- Maximum gross weight: 2,900 lb
- Seats: 1
- Landing gear: fixed
- Engine: Lycoming O-540-B2C5 (piston); 5,492 hours total
- Operator: Evergreen Soaring INC
The flight
- Flight plan: none
- Runway 10/2, 2,701 ft by 60 ft
Weather at the time
- Light: daylight
- Wind: from 020° at 10 knots, gusting 18
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 81°F (27°C), dew point 46°F (8°C)
- Altimeter: 30.08 inHg
- Observation at 11:53 am from KOMK, 24 miles away
Weather report (METAR): METAR KOMK 201853Z AUTO 02010G18KT 10SM CLR 27/08 A3008 RMK AO2 SLP177 T02720083=
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
3 documents, released by the NTSB on November 12, 2021. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 9 pages | View Download |
| 2 | Photographs | PDF, 2 pages | View Download |
| 3 | Record of Conversation A&p/ia | PDF, 1 page | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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.