LAX84FU024

The plt was flying the ultralight vehicle to check it out before allowing his student to solo. Aprx 15 min after the plt took off, he was flying over the arpt at about 400 ft AGL when witnesses heard a 'loud non-metallic' sound from the vehicle. At about that time, it entered a left descending turn. Reportedly, the vehicle made about 3 turns, and during each turn, the bank angle increased. At aprx 200 ft AGL, the plt released his parachute, but the canopy never blossomed. The vehicle impacted in a left wing down, nose low attitude. An exam revealed that the right wing fabric was torn in a manner that was consistent with an in-flt separation. The outboard compression support tube was found 15 ft from the main wreckage. Only remnants of the attach bolt were found. For vehicles manufactured after oct 83, the company had changed the grade of the bolt, but had not issued a service bulletin. However, a service bulletin, ALL-8303-A, was issued concerning loosening of course thread bolts (similar to the attach bolt) but no evidence of compliance was found.