RICHMOND HTS., OH, USA
N725AC
AERO COMMANDER 500S
THE PILOT HAD THE WASTE GATES ON THE TURBOCHARGES ADJUSTED AND WANTED TO TEST FLY THE AIRPLANE AFTER THE WORK WAS COMPLETED. THE AIRPLANE DEPARTED AND HAD REACHED AN ALTITUDE OF ABOUT 1000 FEET WHEN WITNESSES HEARD AN ENGINE SPUTTER. THE AIRPLANE WAS SEEN MAKING A LEFT TURN AND ENTER A NOSE LOW, LEFT SPIN BEFORE IMPACTING THE TERRAIN. A TEAR DOWN OF THE LEFT ENGINE REVEALED THAT THE EXHAUST VALVES IN CYLINDERS #3 AND #5 WERE BURNT THROUGH AT THE VALVE HEAD. THE #5 EXHAUST VALVE HAD A DEEP PREEXISTING DEEP MARK ON THE VALVE STEM. THE FAILURES OF BOTH VALVES WERE SUFFICENT ENOUGH TO CAUSE A POWER FAILURE IN THE LEFT ENGINE.
THE PILOT'S IMPROPER EMERGENCY PROCEDURES AND FAILURE TO MAINTAIN CONTROL OF THE AIRPLANE, WHICH RESULTED IN AN INADVERTENT SPIN AT TOO LOW AN ALTITUDE TO ALLOW RECOVERY. FACTORS IN THIS ACCIDENT WERE; A POWER LOSS IN THE LEFT ENGINE AS RESULT OF THE EXHAUST VALVE FAILURES IN CYLINDERS #3 AND #5.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
