Amateur-built MXS accident near Borrego Springs, California, September 8, 2012
On September 8, 2012 at about 7:35 pm local time, a 2009 amateur-built MXS, registered N21MX, was substantially damaged in an accident during maneuvering (aerobatics) near Borrego Springs, California (Borrego Valley Airport). It was a personal flight under general aviation rules (Part 91). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot’s inability to maintain control of the airplane following the loss of aileron and elevator control due to the forward flight control torque tube assembly’s detachment from the forward bearing. Contributing to the accident was the inadequate construction of the forward bulkhead that held the flight control torque tube assembly in place and the improper installation of the thrust bearings.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 8, 2012 · about 7:35 pm local time
- Place
- Borrego Springs, California · Borrego Valley Airport · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built MXS, built 2009
- Registration
- N21MX · no longer on the register · serial 008
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
During the aerobatic practice flight, the airplane departed controlled flight. The pilot opened the canopy, which then separated from the airplane, and exited the airplane. Due to the low altitude, the pilot's parachute did not fully deploy before he impacted the ground. The accident airplane was 1 of 14 MX-model airplanes. It was the only model built from a kit as an experimental, amateur-built aircraft, and it was constructed differently than the other MX-model airplanes. Postaccident examination of the torque tube assembly revealed that the forward bulkhead holding the torque tube assembly in place was constructed in a way that allowed the bulkhead to flex, which subsequently led the torque tube assembly to detach from the forward bearing during the accident flight and resulted in the loss of aileron and elevator control. Examination also revealed that the forward and aft bearing houses were installed opposite of the correct direction, which allowed the bearings to detach from the torque tube assembly when the front bulkhead flexed.
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 maneuvering (aerobatics) defining event
- Loss of control in flight during maneuvering (aerobatics)
- Collision with terrain or object (not controlled flight into terrain) during uncontrolled descent
The NTSB's findings
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Pitch control › Attain/maintain not possible
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Lateral/bank control › Attain/maintain not possible
- factor Personnel issues › Task performance › Maintenance › Modification/alteration › Other/unknown
- factor Aircraft › Aircraft structures › (general) › (general) › Malfunction
- cause Aircraft › Aircraft systems › Flight control system › (general) › Failure
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: airplane
- Flight time: 4,500 hours in all; 1 in this make and model
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: sngl
- Injury: fatal
The aircraft
- Airframe total time: 311.8 hours
- Last inspection: annual inspection, March 30, 2012
- Maximum gross weight: 1,840 lb
- Seats: 1
- Landing gear: fixed
- Engine: Lycoming AEIO-540 SER (piston); 0 hours total
The flight
- Departed from: L08 Borrego Springs CA
- Destination: L08 Borrego Springs CA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 140° at 6 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 102°F (39°C), dew point 64°F (18°C)
- Altimeter: 29.78 inHg
- Observation at 7:52 pm from TRM, 23 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 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.