Paul Lewis/WASHINGTON DC
Pilot error has emerged as the most likely cause of the recent accident of a new Raytheon T-6A Texan trainer. The US Air Force has restored the type to flight status after a nearly two month grounding following the accident.
It is understood from sources that the accident investigation is focused on the T-6's power control lever (PCL) cut-off finger lift, which may have been mistaken by the pilot for the flap lever. The aircraft suffered a loss of power while on final approach and crashed (Flight International, 12-18 September). Both crew ejected at 165ft (50m) and only narrowly missed the burning wreckage.
The flight was part of an instructor enhancement programme, which gives qualified instructors experience on dissimilar aircraft. There is no limitation on what the "visiting" pilot can do, including landings, as this is left to the aircraft commander's discretion.
Sources add that the T-6's PCL cutoff finger lift is a similar shape and in the same location as the flap lever on the visiting instructor's usual aircraft. Furthermore, the flap labelling is closer to the PCL than the flap lever.
Another possible contributing factor was the absence of supporting training facilities, such as a cockpit familiarisation or emergency procedures trainers. Aircraft were available for familiarisation, but not used. The USAF confirms that a T-6 simulator centre at Randolph AFB - the T-6's base - is still not operational.
The aircraft's commander has been criticised for delaying ejection while trying to restart the T-6's Pratt & Whitney PT6A-68 turboprop below the recommended minimum altitude. The aircraft was at approximately 1,430ft when the engine failed, with no suitable landing site within gliding distance.
Had the pilot been given the opportunity to practice an engine restart on the ground, it is unlikely he would have attempted it in this situation, suggests a crash synopsis obtained by Flight International. Furthermore, the synopsis adds that if the visiting pilot had been more thoroughly briefed on the T-6, "it is doubtful that he would have selected the wrong control".
It is recommended that a simplified emergency restart procedure be developed. The crash has also shown the need for a better emergency oxygen system on the T-6, which in the event of an engine shutdown also stops the onboard oxygen generating system.
Meanwhile, Raytheon is swapping the T-6's Lorri oil cooler for a "more robust" Stewart Warner system able to handle higher pressures. This follows an engine seizure in a NATO Flying Training in Canada T-6 Harvard, forcing the pilot to make a dead-stick landing.
Source: Flight International
