Grumman G-159 Gulfstream I

Shortly after lift off, a low torque sensing switch failed precipitating an auto feather of an engine. The crew mis-handled the required feathering procedure, allowing the propeller to unfeather and windmill. Subsequently, the crew retracted the flaps. This disabled a spring tab on the rudder which was designed to give additional rudder authority for high power/low airspeed situations. The result of the windmilling propeller and the loss in rudder authority was that V(mca) increased from 101 kts to 138 kts. The airplane rolled inverted and crashed. Witness marks on the operating engine's propeller reportedly indicated that the airplane's speed when it crashed was less than 90 kts. All on board, four crew men, four students and one instructor, were killed.

Following an uneventful flight from Cedar Rapids, the crew started the descent to Addison by night. On short final, he encountered heavy rain falls and the pilot initiated a go-around when the airplane descended and crashed onto the runway. All nine occupants escaped with minor injuries while the aircraft was damaged beyond repair.

The approach to Harrisburg-Capital City Airport was completed in poor weather conditions. After touchdown on a wet runway, the crew encountered difficulties to decelerate and the captain eventually decided to make a sharp turn to avoid an overrun. The aircraft veered off runway, lost its undercarriage and came to a halt. While all eight occupants were uninjured, the airplane was damaged beyond repair.

The crew departed Minneapolis-St Paul Airport for a local training mission. En route, while in cruising altitude, the airplane went into an uncontrolled descent until it crashed in an open field located 5 miles southeast of Le Center. The aircraft was destroyed and both pilots were killed.