Aircraft Engine Maintenance - Coke Washing

[kc2aqg]

Just curious if anyone has witnessed or even taken part in this engine maintenance procedure, it sounds and looks quite thrilling! Apparently in order to get rid of any deposits that build up in the compressor section of a turbofan engine, various types of fluids (anything from distilled water to soapy water to even walnut shells according to a.net) are shot into the compressor section of the engine while it's running at flight idle. Deposits in the compressor can increase the Exhaust Gas Temperature (EGT) and wear out the engine prematurely as well as decrease critical flight parameters, so the procedure is obviously to deal with this problem.

Is anyone familiar with this procedure and could tell us more about it? There's one pic of this procedure on a.net with a DC-10 running CF6-50's, but I haven't been able to find any others. My guess is that this procedure is becoming less and less necessary with the advancement of the turbofan engine, but I've read that they are still carried out on the CF6-80 series.

Picture:
http://www.airliners.net/open.file?id=0274416

A.net Thread
http://www.airliners.net/discussions/tech_ops/read.main/120892

[cancidas]

my crew and i used to help the maintainers with engine swings on our helos back in the day. they were a person short, and for a while we had a bird with some very tempermental rebuilt engines. we replaced 3 engines in 5 days because of all the issues we were having. our mx crew chief wanted to isolate the ones that were giving us problems, turns out they were a series of 10 that came out of overhaul as a batch. we never used that overhaul shop again...