Accident Overview
On a maintenance test flight, the pilot and two mechanics were aboard aircraft N63XL. The aircraft was on a straight-in approach to runway 11 from the west. The pilot was advised of traffic ahead and instructed to reduce speed as much as possible, which the pilot acknowledged.
Sequence of Events
Approximately 15 seconds after the speed reduction instruction, the air traffic controller directed the pilot of N63XL to execute a 360° turn to the left for spacing. Shortly thereafter, witnesses observed the aircraft enter a steep bank, followed by a steep spiraling, nose-down descent, culminating in a crash.
Investigation Findings
Post-crash examination found no evidence of preimpact mechanical malfunction or failure of the aircraft or its engines. All three occupants were killed in the accident.
Probable Cause
The official investigation determined the probable cause to be: Failure of the pilot to maintain adequate airspeed, while maneuvering for spacing in the traffic pattern, which resulted in an inadvertent stall at low altitude.