Air/pressurisation involving a Fokker B.V. F27 MK 50, VH-FNI, 75 km west of Taree, New South Wales, on 15 January 1994

The pilot reported that the aircraft was cruising at flight level 230 on track from West Maitland to Point Lookout when the cabin altitude began to increase rapidly at about 80 miles south of Point Lookout. Shortly afterwards the senior flight attendant entered the cockpit advising that the main cabin (passenger) door appeared to be slightly open, and a gap between the door and the frame was clearly visible. The cabin alert master warning illuminated, and a rapid descent was initiated to 10000 feet. The aircraft was diverted to Coffs Harbour and a normal descent and landing was made.

Inspection of the door seal at Coffs Harbour revealed some debris fouling the lower door seal but no other fault could be found. The pressure loss had been due to the door seal being deflated thus causing a gap between the door and the frame. During a flight on 18 January the cabin pressure remained at zero differential until maximum cabin altitude was reached. The pressure controller was replaced after this occurrence and no further problems have been experienced.