N6641Q

The 828-hour commercial pilot of the single-engine agricultural application airplane, took off from a 3,500-feet long by 100-feet wide private grass strip on a northerly heading. During climb-out, as the pilot initiated a turn to the east, the engine began to vibrate and run rough, and subsequently lost power. The pilot reported that he activated the dump valve to released the insecticide payload in order to lighten its weight. The pilot then stated the airplane "rolled to the left past 80-degrees. " The airplane impacted muddy terrain in a near vertical attitude. The airplane was equipped with a 5-point restrain system that held the pilot in place. Examination of the radial engine by the operator revealed the number three cylinder was cracked.