What happened
On May 31, 2012, a Cessna FT337GP Skymaster II, registration N-337ET, was conducting a private flight from Évora, Portugal, to Badajoz, Spain. The flight was intended to include a refueling stop in Évora, but because the fuel service was closed, the crew proceeded with a reduced fuel load. After a routine 20-minute flight, the aircraft was established on the downwind leg for runway 31 at Badajoz Airport.
As the aircraft approached the downwind leg, the front engine failed, followed shortly by the rear engine. The accompanying pilot, who possessed more experience with this specific aircraft type, took control of the flight. He extended the landing gear and initiated a glide toward a cornfield. During the landing, the nose gear strut broke, causing the aircraft to skid and come to rest on its left wingtip and fuselage.
The investigation
The investigation focused on the simultaneous failure of both engines and the fuel management configuration. Investigators examined the fuel selectors and the remaining fuel levels in the wing tanks. While the right tank still contained 35 gallons of fuel, the left tank was empty.
Technical analysis of the fuel selector valves revealed that the engines were likely drawing from the same source. The investigation examined the possibility that the rear engine selector had been set to the 'left' (cross-feed) position while the front engine selector was also drawing from the left tank. This configuration would mean both engines were depleting the same reservoir, leading to total engine failure once the left tank was exhausted.
Findings
- The primary cause of the dual engine failure was fuel exhaustion in the left wing tank.
- The engines failed sequentially because the rear engine continued to run briefly due to the different fuel line lengths between the tanks and the engines.
- The crew had proceeded with the flight despite a low fuel quantity because they believed the remaining fuel was sufficient to reach Badajoz.
- The landing gear was not fully extended at the time of impact, as evidenced by the position of the gear doors.
- The aircraft sustained substantial damage to the airframe and nose gear.