After engine start, with the engines idling, and his feet resting on the brakes, the pilot turned his attention to the inside of the cabin to complete some checks. A short time later the pilot realised that the aircraft was moving. He reduced the power and applied the brakes but before the aircraft was brought to a stop, the left propeller hit a tyre that was being used as a marker at the edge of the parking bay. The pilot shut the engines down and inspected the left propeller. He could find only very slight damage so decided to run the engine. He ran the engine through a range from idle to 2300 RPM and noted no vibration. He then decided the aircraft was fit to fly back to Moorabbin. The return flight to Moorabbin was without incident. After landing the pilot experienced vibration from the left engine. Subsequent engineering inspection revealed the following damage: . One blade bent one degree at the 32 inch station. Blade circlip out of its groove and the groove damaged with rolled edges. . One blade bent one degree at the 30 inch station and twisted two degrees. . One blade bent two degrees at the 30 inch station. Blade circlip out of its groove and the groove damaged with rolled edges. . Allcirclips, blade preload shims, shim plates and shim carriers damaged beyond repair. There was no damage to the hubs or pitch change mechanisms. . In addition, some counter balance weight retaining screws had broken, allowing liberation of the weights.