Primary finding
Probable cause
The airplane builder’s improper installation of the left rear wing strut eyebolt.
Investigator assessment
Analysis narrative
While in a turn at low altitude, the pilot of the open cockpit experimental airplane heard a “loud pop,” followed by a change in the feel of the flight controls. The pilot elected to reduce the engine power to idle and activate the ballistic recovery system (BRS). Seconds later the airplane impacted into an area of trees and came to rest in the trees near the ground. The pilot was able to exit the airplane unassisted. An examination of the wreckage revealed that the left wing rear strut threaded eyebolt had pulled free from the threaded barrel of the wing strut. The thread-to-barrel engagement was measured at 5/32 of an inch with approximately 16 threads exposed. Per the manufacturer’s assembly manual, the eyebolt was to have a minimum of 5/8 of an inch thread-to-barrel engagement with approximately three-and-a-half threads exposed.
Source record
Factual narrative
While in a turn at low altitude, the pilot of the open cockpit experimental airplane heard a “loud pop,” followed by a change in the feel of the flight controls. The pilot elected to reduce the engine power to idle and activate the ballistic recovery system (BRS). Seconds later the airplane impacted into an area of trees and came to rest in the trees near the ground. The pilot was able to exit the airplane unassisted. An examination of the wreckage revealed that the left wing rear strut threaded eyebolt had pulled free from the threaded barrel of the wing strut. The thread-to-barrel engagement was measured at 5/32 of an inch with approximately 16 threads exposed. Per the manufacturer’s assembly manual, the eyebolt was to have a minimum of 5/8 of an inch thread-to-barrel engagement with approximately three-and-a-half threads exposed.