While back-tracking along grass Runway 09, the pilot noticed a “soggy patch” in the centre of the runway which he made a mental note to avoid during takeoff. He reached the end of the runway, turned and positioned the aircraft on the left-hand side and commenced the takeoff. The aircraft accelerated to approximately 40 mph, after which the pilot reported a deceleration coincident with another area of “soggy” runway. This deceleration caused the nose to dip, the nosewheel to detach and the propeller to contact the ground. The aircraft inverted and came to rest facing the opposite direction on its back.
The pilot and passenger, who were both wearing full harnesses, escaped uninjured. The pilot commented that, despite other aircraft taking off on the same runway, walking the runway to assess its condition prior to takeoff might have been wise.