Smoke effects on engine performance
This is a very informative discussion. One thing I have not seen mentioned (have not read all as yet) is any effects on engine performance caused by the constant ingestion of smoke laden air.
Our Company has 2 Bell 212s operating in Indonesia. At present there has been a lot of fires in Sumatra which has been causing severe air pollution in Singapore and Malaysia. This is a yearly problem and is often caused by plantation companies in Indonesia burning off to clear land. A lot of the forest on this land is growing on peat, which smoulders for long periods once ignited. There has been a belated reaction to the complaints from neighboring countries and our Company was approached to take part in the fire fighting efforts. Apart from the fact there is almost no infrastructure on the ground, which make these efforts virtually useless, I am concerned about the effect on engine performance and reliability of the PT6T engines.
In 1997 during an especially bad dry season, I was working for an operator with a fleet of B205A-1's. We were caught in the “Haze” as it was called, in South Sumatra and in Kalimantan, aka Borneo. This caused considerable engine related problems. There is a “tar” like substance in wood or peat smoke and this accumulated inside the compressor section of the engine and caused loss of power. It bakes on to the engine compressor components and is very difficult to remove completely. Our experience with the Bell 205’s was very high Exhaust temps and gradual loss of power, to the point we could no longer operate the aircraft. With the T53 engine, the compressor could be disassembled for cleaning by hand, however this is not possible on the PT6T-3B. In Canada I believe PALL particle separtors are fitting to 205’s which are removed and cleaned every day to remove the tar. I am not aware of any 212/ PT6 filters.
This "tar" also accumulated on the rotor blades as a black sticky coating in as little as two hours flying.
The 212 in used for fire fighting in the USA and Canada, however I believe the conditions are not the same as here. In the USA / Canada, it seems the fires are attacked very quickly after they break out, and the aircraft are mostly flying in clear air before dropping their loads. In Indonesia, the situation is usually critical before any fire fighting action is taken, and by that time the smoke haze is so bad that most of the time the pilots cannot see to fly, and if they can fly, the engines are consuming huge quantities of smoke filled air. A wind shift at night tends to bring a lot of the smoke haze back into the area where it originated, concentrating it and bringing visibility down to a few yards at times, till it clears later in the day.
If anyone is operating 212's on fires I would appreciate any comments on this subject based on your experience.
Thanks
Doc