Amateur-built AIRCAM N123GN accident near Hemet, California

Probable cause

The pilot/builder's improper installation of the left wing during the build process, which resulted in the wing failing during takeoff.

NTSB analysis

The pilot, who was also the owner/builder of the experimental amateur-built kit airplane, was conducting his first test flight in the airplane after having received a special airworthiness certificate 1 week earlier from the Federal Aviation Administration, which allowed him to begin Phase 1 flight testing. On the morning of the accident, several of the pilot's friends and acquaintances gathered to watch his first flight. A video showed that during takeoff, as the airplane reached about 20 ft above ground level, the left wing folded upward. The airplane immediately rolled left and subsequently impacted the ground.

Examination of the airplane revealed that the forward and rear left-wing lift struts remained connected to the wing but were not attached to the fuselage attachment fittings. Further examination revealed that the fittings on the fuselage were intact, and their corresponding bolt holes were undamaged; the bolts were present and secured to the lift struts with washers and nuts but had not been connected to the fuselage through the attachment fittings. The forward and rear right-wing strut were properly attached to the fuselage attachment fittings and the hardware was secure.

Two friends assisted the pilot during the build process. One of them was an airframe and powerplant mechanic, and he reported that the left wing had been removed and reinstalled several times during the build process due to build errors. Each installation required that the attachment hardware be removed and reinstalled, which the pilot performed each time on his own. The mechanic reported that he periodically reminded the pilot to verify that the attachment hardware had been installed correctly, but he continued to find loose screws and nuts throughout the build process.

The pilot likely attempted to install the lift struts on the fuselage after the wing's last reinstallation but failed to ensure that the left-wing lift strut bolts were secured to the fuselage attachment points through the attachment fittings. Although postaccident testing revealed that a correctly installed lift strut was closer to the fuselage along the attachment fitting than an incorrectly installed lift strut, the pilot did not detect the difference between the left and right wings. Postaccident examination of the airframe and engine did not reveal any other mechanical malfunctions or failures that would have precluded normal operation. Therefore, the pilot’s failure to properly attach the left wing to the fuselage likely led to its failure shortly after takeoff.

A Federal Aviation Administration designated airworthiness representative (DAR) inspected the airplane 1 week before the accident and issued the pilot a special airworthiness certificate the same day as he was comfortable with the overall assembly. The DAR was not responsible for the final construction and assembly of the airplane as this was the responsibility of the builder.

Text from the NTSB. Open the NTSB docket for WPR19FA161 for the full record.