What happened
On April 17, 2016, an IBEX Airlines Bombardier CL-600-2C10, registration JA06RJ, was operating flight 084 from Fukuoka to Komatsu. Due to inclement weather at the destination, the flight crew decided to return to Fukuoka.
While cruising at 40,000 feet, the crew received a left bleed duct leak warning accompanied by an aural alert. Following standard operating procedures, the crew began the necessary checklists. However, four minutes later, a right bleed duct leak warning was also triggered. This second failure caused the supply of bleed air from both systems to cease entirely.
In response to the loss of both systems, the crew declared an emergency and initiated an emergency descent. As the aircraft descended through 17,000 feet, a cabin altitude warning indicated that the cabin altitude had exceeded 10,000 feet. The crew donned oxygen masks and continued the descent. The aircraft eventually stabilized at approximately 10,000 feet and landed safely at Fukuoka Airport without any injuries or damage to the aircraft.
The investigation
The Japan Transport Safety Board (JTSB) examined the flight data recorder, cockpit voice recorder, and maintenance diagnostic computer records. Investigators also analyzed the Anti-Ice and Leak Detection Controller (AILC) and the sensing elements retrieved from the aircraft.
Testing of the AILC by the manufacturer, in the presence of the BEA, revealed no functional defects or memory errors. Similarly, ground tests on the aircraft failed to reproduce the reported leaks. Inspections of the sensing elements showed no structural abnormalities, though some oil and fat residue were noted on two of the elements. The investigation also noted that the aircraft had experienced previous 'DUCT MON FAULT' messages related to the left bleed system in the months preceding the incident.