Hawker Beechcraft F33 — Phoenix, AZ

What happened

During a local flight, the airplane departed and climbed to over 8,000 feet mean sea level (msl) on the outbound leg to the north. About 44 minutes into the flight, the airplane began descending after a course reversal to the south on the return for landing. The pilot entered the landing pattern, however, due to multiple airplanes in the traffic pattern he extended downwind, and asked the controller in the air traffic control tower to call his turn to base leg. After getting established on a 3-mile final, the controller notified the pilot that the airplane appeared low. The pilot responded that he was having engine problems and would try to make it to the runway.

Witnesses reported that the airplane was low on final approach and that the engine was sputtering and backfiring. The airplane subsequently collided with a building short of the runway.

Postaccident examination of the wreckage found an engine monitoring unit on board. A download of the data indicated normal readings until the return descent where it appeared the pilot didn't enrich the mixture. As the pilot was turning onto the base leg, data on the engine monitoring system indicated that the engine revolutions per minute (rpm) started a gradual decrease, and the exhaust gas temperatures (EGT) for all six cylinders became erratic. The EGTs for cylinders one, two, and six dropped slightly, and stayed at higher values than the other cylinders. When the EGTs became erratic, the engine was likely losing combustion (power) in some cylinders.

During the postaccident engine examination, the mixture lever was found loose on the throttle shaft but it could not be determined if it was functioning properly at impact. The reason for the partial loss of power could not be determined.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.