1966 VH-RMI Flight 149 Crash in Queensland

Flight Details and Emergency Declaration On 22 September 1966, a Viscount 832 registered VH-RMI was operating Flight 149, a regular public transport service from Mt. Isa to Longreach in Queensland, Australia. The aircraft carried four crew members and twenty passengers. It departed Mt. Isa at 1208 Australian Eastern Standard Time and climbed to Flight Level 175, with an expected 73-minute flight to Longreach. The flight appeared uneventful until 1252, when the Longreach Flight Service Unit received a report from the crew that the aircraft was in an emergency descent. Two minutes later, the crew reported fire warnings for the No. 1 and No. 2 engines, noting that one warning had ceased and that the propeller of the other engine could not be feathered. At 1259, information relayed through another aircraft in the area indicated a visible fire in the No. 2 engine and that VH-RMI was diverting below 5,000 feet to Winton, a town about 20 miles to port of the planned track and 90 miles short of Longreach. No further communications were received from the aircraft. ## Crash and Aftermath At 1303, witnesses in the Winton area reported black smoke in the air west of the town. The smoke was later linked to VH-RMI, which crashed in light timber on level ground about 131 miles short of Winton aerodrome. The aircraft disintegrated on impact, and all 24 occupants were killed. ## Official Findings The official investigation found that the accident was caused by the failure of the means securing the oil metering unit to the No. 2 cabin blower, which became ineffective and initiated a fire within the blower. The fire spread to the wing fuel tank and substantially reduced the strength of the main spar upper boom. The investigation determined that the port wing failed upward between the No. 1 and No. 2 engines at approximately 1302:30 Eastern Standard Time, when the aircraft was at 3,500 to 4,000 feet above ground level. The wing failure resulted from weakening of the main spar due to a fire in the No. 2 cell of the No. 2 fuel tank. The fire originated in the No. 2 cabin blower and traveled through the rear of the No. 2 engine nacelle and the port wheel bay to the fuel tank. The blower fire was initiated by a rotor break-up, after which the blower was driven in an out-of-balance condition by the quill shaft long enough for the metering unit to separate from the rear end cover due to vibration. The separated metering unit continued to be driven, and lubricating oil continued to be supplied. The driven rotor lost its rear stub shaft radial location, causing metal-to-metal contact that generated enough heat to ignite the oil in that area. The investigation concluded that the source of the rotor break-up could not be determined.