The Piper Navajo was substantially damaged after an explosion in its right wing during a takeoff attempt. No one among the Airline Transport-rated pilot or the six passengers aboard were injured. The pilot later told investigators that, about 700 feet into the takeoff roll, the left engine seemed to lose a little manifold pressure, and the pilot aborted the takeoff. While decreasing power during the aborted takeoff, the outboard section of the right wing exploded. The airplane was stopped on the runway, and its occupants evacuated. Examination revealed that the upper and lower portions of the outboard wing skin had separated from the wing structure. All wiring routed though the wing section was absent of chafing, melting or burning. Before beginning the takeoff, the pilot estimated that each wings outboard tanks were half full.