What happened
The aircraft was climbing to an altitude of 3,000 feet approximately four miles east of Reading Airport when the crew began practicing instrument approach procedures. Shortly after leveling off, the flight crew detected an odor resembling burning insulation but could not immediately identify the source. At approximately 1137, a crew member went aft to investigate and found the cabin filled with dense smoke, reporting that the entire cabin was on fire.
The crew attempted to extinguish the fire using cockpit equipment but were unable to enter the cabin due to intense heat and thick smoke. The smoke quickly infiltrated the cockpit through the open galley door, severely reducing visibility. An attempt to clear the smoke by opening the cockpit hatch actually increased the flow of smoke into the flight deck. With instruments obscured, the pilot attempted to fly back to Reading Airport with his head out the side window to maintain visual reference.
As heat and smoke intensified, control of the aircraft became impossible. At an altitude of about 100 feet, two miles northwest of the airport, the pilot attempted a blind ditching maneuver. The aircraft struck electric power lines, clipped a tree, and skidded across a hay field for approximately 1,000 feet before disintegrating partially and coming to rest in a pasture beyond a road. Fire broke out from ruptured fuel tanks, consuming much of the wreckage.
Findings
Upon arrival at the scene, one pilot was found walking away from the wreckage while another lay on the ground nearby. Five crew members died in the accident, with one fatality occurring shortly after hospital admission and four perishing in the wreckage. The official investigation determined that the probable cause was a failure in generator lead through-stud installations in the forward baggage compartment. This defect caused electrical arcing and intense local heating, which ignited fuselage insulation and generated smoke dense enough to prevent sustained aircraft control. A contributing factor was identified as deficiencies in inspection systems that allowed these defects to persist over time until they created a hazardous condition.