A C-130 tanker plane joined the ranks fighting a forest fire blazing through an area just north of Yosemite National Park. The plane came in low to the ground trailing a red flow of fire retardant above tall green pines. Suddenly, the wings broke off. The fuselage rolled left and spiraled nose first into the ground, exploding in a ball of flames. As investigators began to gather evidence suspicions were aroused when another fire fighting aircraft - a PB4Y-2 - crashed in Colorado under similar circumstances. Was there a connection? The NTSB grounded all fire retardant dropping aircraft. The similarities of those crashes prompted the NTSB to reopen its investigation into the 1994 crash of a C-130A, which, like the others, had been converted to a firefighting air tanker. Had the same hidden problem brought down all three planes?