Hydraulic Leak and System Loss
The hydraulic leak originated from a failure of an O-ring in the number 1 thrust reverser selector valve. In response, the flight crew performed checklist actions that resulted in switching off the pumps supplying the number 1 hydraulic system. This led to the loss of associated systems, including nose wheel steering. After landing, the aircraft required a tow to the gate by a tug due to the loss of nose wheel steering.
APU Contamination
The captain decided to start the auxiliary power unit (APU) inflight to provide air for the air-conditioning system after landing and electrical power after engine shutdown. However, the location of the hydraulic leak relative to the APU air intake, combined with a gap between the APU intake door actuator rod cut-outs, allowed hydraulic fluid to contaminate the air-conditioning system. This contamination occurred when the ground-flight logic switch detected the aircraft was on the ground and the APU began supplying air to the air-conditioning system.
Fumes in Cabin
After fumes were detected in the cabin, the captain's first action was to switch off the air supply from the APU. Following this, the engines supplied air for the air-conditioning system. However, by that stage, various parts of the air-conditioning system were already contaminated with hydraulic fluid. Consequently, fumes continued to enter the cabin through the air-conditioning system.
Emergency Evacuation
During the emergency evacuation, the R1 door slide did not deploy. A maintenance inspection found that the R1 door was disarmed, and no fault was found with the door operating mechanism. It is likely that during the emergency evacuation procedure, the cabin crewmember at the R1 door reverted to previous experience and disarmed the door prior to opening it, which prevented the slide from automatically deploying.