What happened
On 8 January 2013, a Tucano T Mk1, registration ZF349, operated by Number 1 Flying Training School (1FTS), departed RAF Linton-on-Ouse for a routine Partial Test Flight. The crew consisted of an experienced handling pilot and a student pilot acting as a scribe. The flight was intended to verify engine performance following recent maintenance work.
During the flight, while conducting power checks in Engine Electronic Control (EEC) Manual mode, the handling pilot noticed unstable torque readings. While attempting to transition the EEC switch from Manual back to Normal mode, the aircraft experienced an immediate and significant increase in drag alongside a loss of thrust. The crew also noted a physical pulse through the airframe and observed that the torque gauge had dropped to zero.
Suspecting an engine failure, the handling pilot initiated an emergency procedure for an Actual Forced Landing on Runway 2/1. The pilot transmitted a Mayday call, deployed the landing gear using both the normal and standby systems, and set the flaps to the fully down position. The aircraft touched down approximately 2340 ft beyond the runway threshold with its wheels up. The aircraft skidded along the centerline for roughly 3700 ft before the pilot steered it off the runway into the grass. There were no injuries to the crew, though smoke was observed emanating from the cockpit area following the impact.
The investigation
The investigation examined the aircraft's recent maintenance history, noting that a replacement engine had been installed approximately 17 hours prior to the accident. Investigators analyzed the Accident Data Recorder (ADR) to establish a precise timeline and conducted in-depth testing on the engine ancillaries, specifically the Fuel Control Unit, as well as the landing gear system.
Findings
- The primary cause of the incident was the sudden loss of thrust and increase in drag occurring immediately upon re-selecting the EEC switch to Normal mode.
- The crew experienced a total loss of torque during the transition between engine control modes.
- The aircraft's landing gear was not fully extended at touchdown, resulting in a wheels-up landing.