At a low height after takeoff the aircraft stalled and entred an incipient spin. The pilot and two of the three passengers were fatally injured. The investigation found that the right engine was not running and its propeller was not in the feathered position at impact, and that a significant quantity of water was present in the right fuel tank before the aircraft’s departure.
Tests showed that with the right hand fuel filler cap in place, water falling or flowing on the upper wing surface could enter the right hand fuel tank. The fuel suction filters fitted in the aircraft’s fuel tanks were of the original production standard. The early-production-standard fuel suction filters were of a design which would, with a certain volume of water present in the sump, permit that water to enter the engine fuel supply under longitudinal acceleration and/or nose-up pitch attitude.
Three Safety Recommendations were made.