According to Griswold, the B-17F's engine intercoolers were set on "high".
"Due to the apparent inexperience of the co-pilot in the proper use of intercoolers, the oil was heated excessively until it became so thin that the oil pressure dropped and the fuel mixed was leaned to such an extent that is caused detonation," he said. "This resulted in burning through the tops of the pistons and scoring of the piston and cylinder walls of 3 of the 4 engines."
According to the accident report from the Air Corps Accident Committee, it was found through Griswold's research, that this incident forced the aircraft's engine oil to be heated and thinned too much. The tragic result was that the plane was unable to maintain enough power to keep itself in the air.
"The problem was quickly discovered by the flight engineer, but it was too late to reverse the effects and continue to fly. The engine cylinders began to explode, crippling 3 of the four engines," he said.
According to Griswold, at the time of the crash in 1943, the B-17F was a new and highly sophisticated aircraft.
The plane performed flawlessly during its pre-flight check which was conducted by Engineer Staff Sgt. Jessie Pace and Assistant Engineer Staff Sgt. Oscar Krummel before Leaving Grand Island, Neb., on the morning of June 27, 1943.
"According to statements from crash survivors, Pace noted that the engine intercoolers were put in the "hot" position by the co-pilot for 15 minutes-without the pilot 's knowledge," said Griswold. "Engineer Pace corrected the issue but the damage was too far along to fix. Pace and the investigation team of the War Department Accident Committee agreed this was the cause of this tragedy."
Griswold said Assistant Flight Engineer Krummel stated the aircraft was also overloaded, weighing 68,000 pounds on take-off; the B-17F was rated for a maximum loaded weight of 65,500 pounds.