CHI95LA078

The flightcrew reported that the airplane was not pressurized for the 15 minute repositioning flight, and the maximum altitude reached was 3,100 feet. They reported no unusual occurrences during the flight. Postflight inspection revealed that pallets from the 3L position had shifted aft and punctured the aft pressure bulkhead in two places. A flight mechanic reported that he had secured the pallets in position 3L and 3R when they were placed there two flights before the accident flight. He 'flipped up three rows of locks aft of each pallet position.' The flight engineer reported that he had inspected the pallets during the preflight and 'the left side had an overhang' and he could not see the aft locks. He said the front locks were installed.

On January 28, 1995, at 1910 eastern standard time, a Boeing 747- 238B airplane, N706CK, operated by American International Airways Inc., sustained substantial damage to the aft pressure bulkhead when cargo pallets shifted during takeoff from the Willow Run Airport, Ypsilanti, Michigan. Three crew members and a mechanic onboard the airplane reported no injuries. The repositioning flight, conducted under 14 CFR Part 91, landed uneventfully at the Detroit Metropolitan Wayne County Airport approximately 1930.

Visual meteorological conditions prevailed and an IFR flight plan was filed.

The flight crew reported the airplane was not pressurized for the 15 minute repositioning flight and the maximum altitude reached was 3,100 feet. They reported no unusual occurrences during the flight and did not know the pallets had shifted until they conducted a postflight inspection and discovered the stack of pallets that had been located in position 3L had shifted aft.

In a written statement, the flight mechanic reported that he had secured the pallets in position 3L and 3R when they were placed there, two flights before the accident flight. He "flipped up three rows of locks aft of each pallet position." He stated that "sometime after the airplane arrived in Ypsilanti, the pallets had to be either moved, or the locks disengaged, and not resecured."

The flight engineer reported that he had inspected the pallets during the preflight and "the left side had an overhang" and he could not see the aft locks. He said the front locks were installed.

Photographs of the pressure bulkhead, provided to the NTSB investigator, exhibited two holes in the four o'clock and seven o'clock positions as viewed from the cargo area.