During the takeoff roll, the airplane's main landing gear partially retracted and the nose landing gear collapsed completely. The airplane's left wing impacted the ground, resulting in structural damage. The airplane came to rest in an upright position on the runway, and the pilot and the airplane's mechanic were able to exit the airplane unassisted. Following the accident, an examination of the landing gear revealed that the mechanic had wired the landing gear squat switch incorrectly; resulting in a retraction of the landing gear once the landing strut was extended.