What happened
While cruising at 9500 feet, the pilot observed smoke emitting from the left engine cowling. An attempt to reduce power to the affected engine was unsuccessful because the throttle lever became immobile. Although turning off the left fuel selector initially suppressed the flames, the fire reignited approximately three minutes later.
During the subsequent emergency descent, the aircraft experienced a total loss of electrical power. This forced the crew to manually extend the landing gear. As the aircraft performed its landing roll, the left landing gear collapsed while the wing remained on fire.
Findings
An inspection of the engine identified that a fuel pressure return line located on the firewall was only finger-tight. While the secondary fitting was secure, the loose connection failed to meet the torque specifications of 30-40 inch-pounds required by the maintenance manual. Additionally, investigations determined that the pilot did not adhere to established emergency procedures for managing an in-flight engine or wing fire.