Emergency services are on the scene treating the pilot, a man in his 70s, for head injuries.
The plane was seen on top of a storage shed with its tail bent.
The pilot is in a stable condition.
Fire and rescue crews were seen using a cherry picker and ladders to get onto the hangar roof.
It is not yet known how the plane came to be on the hangar roof.
Wedderburn Aerodrome is a small airstrip in Sydney’s southwest that caters mostly to recreational pilots.