On November 21, 1997, at 1030 eastern standard time, a McDonnell Douglas DC-9-15, N564PC, operated by Kitty Hawk, Inc., was substantially damaged when unsecured cargo pallets impacted the aft bulkhead when power was applied during takeoff. The airline transport pilot and first officer were not injured. The 14 CFR Part 91 flight was departing from Syracuse Hancock International Airport, Syracuse, New York, with Willow Run Airport, Ypsilanti, Michigan as the destination. The pilots aborted the takeoff and had the pallets secured. The airplane departed and landed uneventfully at Willow Run Airport. The airplane was removed from service and inspected for damage. Visual meteorological conditions prevailed and an instrument flight plan had been filed. The captain reported that he and the first officer completed a flight from Dallas-Ft. Worth to Syracuse and had just checked into the hotel when they received a call and were "directed" to fly a non-revenue positioning flight to Willow Run Airport, Ypsilanti, Michigan. The pilots returned to the airport and prepared for the positioning flight. The captain reported that the airplane was empty except for the cargo deck pallets that had been stacked at the "B" position (toward the front end of the cargo deck) instead of being spread out over the cargo deck floor. The captain reported that prior to departure he calculated a weight and balance, filed a flight plan, and obtained a release from company Flight Following. He reported that the first officer conducted a preflight, set up the cockpit, and ensured the cargo area was secured. The captain reported that before manning the aircraft for departure, he visually checked the stack of pallets while he was at the forward cargo safety/barrier net. He observed seeing the cargo hold down straps across the stack plus straps holding down a pallet jack on top of the stack. The captain reported he "...concluded the cargo rig was secure without actually crossing through the forward cargo safety/barrier net to physically check the straps holding the stacked cargo deck pallets." The first officer reported, "The preflight was routine, in the cargo compartment the pallets were stacked and strapped and locked in place." The captain reported that when power for takeoff was applied and the airplane started to accelerate, he heard a noise that sounded like a pallet being rolled on the cargo deck in the cargo bay. He immediately reduced power to idle, and taxied the airplane back to the cargo ramp. The pilots visually inspected the airplane and concluded that no apparent damage had been done. The cargo pallets were secured to the cargo deck, the pilots re-filed the flight plan, and the positioning flight was continued. They departed Syracuse and had an uneventful flight to Ypsilanti where they blocked in at 1249 central standard time. An examination of the damage revealed that both vertical beams at the STA:786 bulkhead were sheared at the floor restraints and had moved 4 inches aft. The floor restraints in the seat track had broken loose, the vertical bulkhead supports were broken at the floor attachment, and the engine pylon front spars were bent aft. A company aviation mechanic in Syracuse reported that he had been told by the company that the airplane was not scheduled for a flight. The mechanic told the cargo handlers that it would not be necessary to spread out the pallets on the cargo deck floor, but to simply stack them together and place them on the airplane's cargo deck. There were six pallets that normally are placed on the cargo deck floor in corresponding pallet positions A - F. The normal procedure would have been to place and secure the six pallets in their respective positions. In this case, the cargo handlers strapped five of the pallets together with cargo straps and placed them on the pallet which was secured in the "B" position. The five cargo pallets were not secured to the pallet in the B position. The pallet jack was secured on top of the five pallets by cargo straps.