Fairchild Industries Inc SA227-DC, VH-WAJ

Shortly after landing at Perth and taxiing clear of the runway,
the crew of the Metroliner observed smoke accumulating and
increasing in intensity in the cockpit. The crew stopped the
aircraft on the taxiway, shutdown the engines, notified air traffic
services of the problem and commenced disembarkation of the
aircraft. After the passengers had safely disembarked, the pilot in
command re-entered the aircraft and observed that, with the engines
stopped, the smoke had begun to dissipate from the cabin and
cockpit.

The operator's maintenance investigation found that the right
air cycle machine (ACM) had leaked oil into the airconditioning
system, that had then entered the cabin as smoke and fumes. The ACM
turbine had seized. The Chief Engineer reported that the company
conducted a fleet wide analysis to see if a failure trend could be
identified for the ACM units. They determined that the Metro fleet
had used a total of ten ACM's since 1999, with six being used by
the incident aircraft alone. The usage was evenly distributed
between left and right installations of the units. The conclusion
was that the air delivery system to the ACM's might have a partial
blockage leading to the premature failures.