Incident
On 14 March 2000 at 1150 UTC, a North American T-6G Harvard (registration G-BKRA) was involved in a ground loop while taxiing at Leeds Bradford International Airport, Yorkshire. The aircraft sustained minor damage to the starboard wing tip and possible undercarriage damage. Neither of the two crew members (commander and student pilot) were injured.
Sequence of Events
The aircraft was conducting a one-hour type familiarisation flight for a student pilot. The commander occupied the front seat and the student the rear. After receiving clearance to enter and backtrack Runway 14, the pilot began taxiing on Runway 14 to maximise runway length for departure from Runway 32. The actual wind was 280°/20–30 kt, varying between 280° and 320°. Although the wind speed was higher than forecast, no control difficulties were initially experienced and the aircraft felt stable. To expedite the backtrack, the pilot increased taxi speed, which, though faster than normal, did not seem excessive. Shortly after, a marked tail wheel shimmy developed. To avoid damage to the tail wheel unit, the pilot gently eased the control stick forward to a point he considered just beyond neutral. Almost immediately, the tail wheel unlocked, allowing it to free-castor. Given the strength and direction of the tailwind component, the aircraft ground looped to the right through 270°.
Aircraft and Pilot Information
The North American T-6G Harvard (1951) was powered by one Pratt & Whitney R1340-AN1 piston engine. The commander held an Airline Transport Pilots Licence, was 36 years old, and had 4,500 total flying hours (150 on type, with 150 hours in the last 90 days and 70 in the last 28 days).
Pilot's Assessment
The pilot noted that the Flight Manual for the Harvard advises that for downwind taxiing the control stick should be held forward to prevent the tail from lifting, but warns that if the stick is full forward, the tail wheel unlocks and free-swivels; for steering engagement, the stick must be held a few inches aft of full forward. The pilot considered that he moved the stick too far forward, causing the tail wheel to unlock and initiating the ground loop. He further concluded that if he had been taxiing at a lower speed, the situation would have been manageable and no damage would have occurred.