After an intermediate stop in Frankfurt the Boeing 747 having arrived from New York taxied to runway 25R to depart to Amsterdam. Three crew members, three passengers, and two pallets with the cargo which had not been unloaded but was to be flown to its destination airport Amsterdam, were on board the cargo airplane. When starting the takeoff run the pallet on the right side detached and slid backwards causing substantial damage to the airplane. Due to the centre-of-gravity shift, the Boeing rotated into a nose-up attitude. The pilot-in-command rejected the takeoff run at a speed of about 70 kt. The airplane exited the runway to the left and came to rest between the runways. PROBABLE CAUSE: “Even though it has been shown by tests that the side locks if not correctly engaged, may open when the pallet is pushed sidewards, it must be assumed that the shifted pallet had not been secured. The simple design of the locks to restrain the pallets requires thorough visual inspection since the locks do not automatically take a definite open or locked position. Pressure of time, lack of supervision and non-adherence to operational procedures together with communication difficulties between the crew and the ramp service men led to a chain of unfortunate conditions. The necessary final checks concerning loading, in the end, were omitted or were conducted only superficially.”