The pilot had flown to Whirly Hole the previous day and after helping with the muster, the aircraft was landed and left overnight on the strip. Next morning, when the pilot attempted to start the engine, he found that he had left the master-switch in the ON position, which flattened the battery. He attempted to hand start the engine but it failed to fire, so after re-priming he set the throttle to a position which equates to about 1200 RPM. Upon the second start attempt, the engine fired but the aircraft moved off at a reasonable speed, with the pilot unable to intercept it before it struck a tree. Prior to starting the engine, although the pilot checked the park brake lever was still in the ON position, he did not re-apply pressure to the brake pedals. It is probable that hydraulic pressure bled off during the night or that the brakes were only lightly applied the previous evening. The brake system was serviceable and the pre-start checks include a requirement to test and set the brakes.
