Ansett-ANA Flight 149 took off at 12:08 for a 73-minute flight to Longreach. The flight progressed, apparently uneventfully, until 12:52 when the Longreach-Flight Service Unit heard the crew of VH-RMI say that it was on an emergency descent and to stand by. Two minutes later the aircraft advised that there were fire warnings in respect of no. 1 and 2 engines, that one of these warning conditions had ceased and that the propeller of the other engine could not be feathered. At 12:59, information from the crew of VH-RMI, relayed to Longreach through–the crew of another aircraft in the vicinity, indicated that there was a visible fire in no. 2 engine and that the aircraft was diverting below 5000 ft, to Winton. The Vickers Viscount was descending at an indicated airspeed close to 170 knots between 3500 and 4000 ft above ground level . At this point the port wing failed upwards between engines 1 and 2. It struck the top of the fuselage, which at the same time was cut open by the blades of the no. 1 engine, and fell away from the remainder of the aircraft . The cabin shell above floor level was quickly broken away by air loads until eventually the rear fuselage and empennage also separated from the aircraft. The remaining forward fuselage, with the lower mid fuselage, starboard, wing and, engines and port wing stub with the no. 2 engine still attached, struck the ground at the edge of a clay pan and was immediately engulfed in flames. PROBABLE CAUSE: “The means of securing the oil metering unit to the no.2 cabin blower became ineffective and this led to the initiation of a fire within the blower, which propagated to the wing fuel tank and substantially reduced the strength of the main spar upper boom. It is probable that the separation of the oil metering unit arose from an out-of-balance condition induced by rotor break-up but the source of the rotor break-up could not be determined.”