What happened
While climbing to 18,400 feet m/sl, the pilot of a Cessna 421 reported a malfunction involving the turbocharger and indicated a potential loss of power in the left engine. Due to the inability to maintain altitude, the pilot reversed course and diverted to an alternate airfield. During the final approach, the aircraft drifted right of the runway centerline. While attempting to correct the course by turning back toward the centerline, the aircraft entered a left turn that steepened into a spin. The plane crashed approximately 0.5 miles short of the runway, resulting in eight fatalities.
At the time of impact, the aircraft's flaps were fully extended. Documentation from the pilot's clipboard noted that the left engine's fuel flow and cylinder head temperature had dropped to zero, with manifold pressure falling to 10 inches, though a change in the boost pump setting temporarily increased manifold pressure to 18.5 inches.
Findings
Investigation of the left engine's exhaust system revealed a warped flange and signs of exhaust gas leakage at the wastegate outlet of the Inconel Wye collector. The left engine was producing low power during the crash, and neither propeller had been moved to the feathered position.
Technical analysis determined the aircraft was operating at an unsafe weight and balance configuration. The gross weight was 7,645 pounds, exceeding the maximum allowable 7,450 pounds, and the center of gravity was 158.32 inches, which was beyond the 158-inch limit. Additionally, while recent inspections had been performed on the engine and turbocharger, there were no logbook records regarding the maintenance or replacement of exhaust system components. The pilot had not undergone recurrent training in this specific aircraft model since 1984.