What happened
During a 15-minute repositioning flight, the crew operated the unspecified aircraft at a maximum altitude of 3,100 feet. The flight was conducted without cabin pressurization, and the crew reported no unusual occurrences during the duration of the flight.
The investigation
A postflight inspection of the aircraft revealed that pallets located in the 3L position had shifted toward the rear of the plane. This movement resulted in two punctures to the aft pressure bulkhead.
An investigation into the cargo securing procedures provided conflicting information regarding the state of the pallet locks. A flight mechanic stated that he had secured the pallets in both the 3L and 3R positions during a flight occurring two rotations prior to the accident, noting that he had flipped up three rows of locks aft of each pallet position.
However, the flight engineer reported that during his preflight inspection, the left side of the cargo area had an overhang. Due to this overhang, the engineer was unable to see the aft locks, though he confirmed that the front locks had been installed.