On 19 May 2015, the pilot of a Cirrus SR22T aircraft, registered VH-EPG, planned to conduct a flight from Moorabbin to Mildura, Victoria, under the instrument flight rules (IFR) with one passenger. At about 0812 Eastern Standard Time (EST), the aircraft departed Moorabbin Airport, and the pilot conducted a climb to flight level (FL) 180.  During the climb, the pilot selected the de-ice system on, and switched it off after levelling off at FL180.

About 5 minutes later, the pilot received an ‘alternate air open’ alert on the primary flight display. The alert indicated a blockage, probably due to ice, of the induction air intake to the engine. The alternate air then routed unfiltered air to the engine. Soon after the alert illuminated, light brown smoke entered the cabin through the vents. All engine indications were normal and the electrical system was functioning normally. The source of the smoke appeared to be forward of the engine panel, with no flames or external smoke visible.

The pilot assessed the probable cause of the smoke to be a turbocharger issue and elected to conduct a descent. When the pilot reduced power for the descent, the smoke cleared. However, after reaching FL150, the pilot resumed cruise power and the smoke reappeared.

At about 0852, the pilot declared a PAN and requested further descent and a diversion to Bendigo, Victoria. During the descent, the smoke evaporated, but a moist brown residue was depositing on the windscreen reducing the visibility.

The pilot conducted an instrument approach to runway 17 at Bendigo Airport. The pilot could then see the runway lights through the misted up windscreen and rain, but reported difficulty in seeing the ground. When on final approach to the runway, about 0.6 NM from the threshold, the pilot suddenly sighted a row of trees. The pilot immediately conducted a climb to avoid them, and estimated that the aircraft cleared the trees by a few feet. The pilot then landed the aircraft on the runway threshold. The pilot and passenger were uninjured and the aircraft was not damaged.

This incident provides a timely reminder to flight crews of the importance of monitoring the flight instruments when encountering areas of reduced visual cues.


Aviation Short Investigations Bulletin - Issue 43

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