TWA Martin 4-0-4 N40403 took off from Pittsburgh for an IFR flight to Newark. The first officer was in the left seat, being line-checked by a captain. After becoming airborne from runway 23, a sharp yaw was experienced while the first officer reduced power at an altitude of about 100 feet. Almost simultaneously the no. 1 zone fire warning light for the left engine illuminated; the fire bell didn’t ring. The first officer then presumably moved the no. 1 throttle rearward intuitively. The captain didn’t see the fire warning light and only noted the power loss indicated by the BMEP gauge. He then pulled the mixture to idle cut-off. The first officer reached for the manual feathering button but the captain informed him that the automatic feathering device would cause the no. 1 prop to feather. This did not happen however, because the throttle had been retarded aft of the switches that armed the autofeather system. The aircraft continued to yaw to the left due to the drag of the no. 1 prop until it struck the ground 1690 feet past the end of the runway. It appeared that the fire warning was the result of the failure of an exhaust connector clamp which allowed heat exhaust gasses to impinge an overheat detector. PROBABLE CAUSE: “Uncoordinated emergency action in the very short time available to the crew, which produced an aircraft configuration with insurmountable drag.”