What happened
Following the completion of an aerial survey, the aircraft arrived at Brown Field to clear U.S. Customs. During the subsequent engine restart, an observer noted two brief yellow flame bursts exiting the left engine exhaust. As the aircraft proceeded to taxi, a popping noise was heard, which ceased once power was applied to cross runway 26L. The aircraft paused briefly before entering the runway, and no run-up was observed by witnesses.
While climbing between 600 and 1,000 feet with the landing gear retracted and wings level, witnesses heard a series of popping sounds resembling automatic gunfire. The aircraft then performed an abrupt 45-degree left bank while the nose dipped. Following this, the nose pitched up toward the horizon, and the aircraft entered a left turn, becoming inverted in a roughly 30-degree nose-low attitude. The aircraft eventually leveled into a shallow right bank before disappearing from view behind terrain and buildings.
Findings
Maintenance records from May 1997 indicated that the left engine manifold pressure had been fluctuating during flight. A subsequent work order in June 1997 involved the replacement of the left engine differential pressure controller to address fluctuations of 2 inHg and RPM variations of 100 during cruise. A test flight conducted on the day of the accident by the pilot indicated that the discrepancy persisted at cruise power settings, though the engine appeared normal at high and low power settings.
Post-accident inspections of the aircraft components revealed that the left engine differential pressure controller was damaged, and the left density controller was too damaged to undergo testing. While the right engine controllers and fuel pumps functioned within specifications, both fuel servos were found to be damaged. Additionally, one injection nozzle on the left engine was found to be partially plugged.