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Flight 304 departed Chicago on an IFR flight plan at 1304 and climbed to its cruising altitude of 19,000 feet, in accordance with its ATS clearance. Gross weight of the aircraft at takeoff was 54,179 pounds, 3,221 pounds below the allowable, and the load was properly distributed.
At approximately 1345 in the vicinity of Flat Rock, Michigan, powerplant difficulty developed. During an emergency descent the No. 4 propeller broke loose and one blade passed through the fuselage, killing one person and injuring several others. The flight continued to Windsor, Ontario, where an emergency landing was made without further damage to the aircraft or injury to its occupants. Not until after landing did the pilots learn that a propeller blade had passed through the fuselage.
Investigation
According to the pilots the flight was routine until approximately 1345, at which time they noted a momentary drop in r. p. m. of No. 4 engine, 200 to 300 below the normal cruise r. p. m. of 13,600. Engine r. p. m. returned to and remained normal for about five minutes, then No. 4 engine r. p. m. was observed to increase rapidly to approximately 13,900 or 14,000. Shortly thereafter and concurrently with attempting to feather the propeller, the overspeed increased appreciably and feathering attempts, using both the manual and automatic systems, were unsuccessful.
