What happened
On January 2, 2025, an experimental Vans Aircraft RV-10, registration N8757R, was destroyed during an accident near Fullerton, California. The flight, operated under Part 91 personal flight rules, resulted in 2 fatal injuries for the pilot and passenger, as well as 19 ground injuries, consisting of 8 serious and 11 minor injuries.
Prior to takeoff, the aircraft was observed taxiing from its hangar toward the runway 24 runup area. Security footage showed the aircraft in the runup area for approximately three minutes, during which time the left door was not flush with the fuselage. At approximately 14:07, the aircraft began its takeoff roll. Data from the Electronic Flight Instrument System (EFIS) indicated that by the end of the runway, the aircraft had climbed to 150 feet mean sea level (msl) at a ground speed of 108 knots.
Shortly after takeoff, the pilot transmitted an "immediate landing required" message to the Fullerton control tower. After being cleared to land on any runway, the pilot indicated an intention to return for landing on runway 24. During the subsequent left downwind leg, witnesses observed the aircraft flying at a lower altitude than expected and performing aggressive left banks. Witnesses noted the aircraft's nose dropped and it entered a dive toward a warehouse. Just before impact, a white, panel-like piece was seen falling from the aircraft.
The aircraft struck the roof of a furniture manufacturing facility approximately 1,500 feet short of the approach end of runway 24. The impact occurred within a warehouse containing pallet racks loaded with foam and wood furniture. The forward cabin and most of both wings were destroyed by fire, while the engine and instrument panel were located 40 feet beyond the main wreckage.
The investigation
Investigators examined the aircraft's door locking mechanism, which utilized "gull-wing" doors mounted to the roof via steel hinges. The primary lock used tubular aluminum pins and a rotary gear assembly. While a secondary safety latch system was available as a retrofit, investigators found that the secondary safety latch had not been installed on N87ly.
Examination of the wreckage revealed the pilot had modified the standard locking system by replacing aluminum pins with solid steel pins and replacing polyethylene blocks with chamfered aluminum blocks. Additionally, the door latch indicator system, which used magnetic reed switches to alert the pilot via LED lamps, had been modified; only two switches were installed instead of four. This modification meant the system could not warn the pilot if the forward latch pins failed to fully engage.
The left cabin door was found on the building's roof, 150 feet southeast of the impact point. The door handle was found just short of the fully closed and locked position, meaning the locking button had not engaged. The lock pins were found extended 1/2 inch from the door ends; when tested, the pins extended an additional 7/16 inch as the handle moved forward.