smoking C20R

[MarkR]

We have a C20R engine, MD520N installation, 150 hrs since overhaul. Has been standing for 9 years and was opened for bulletins and checked out. Three min. after shutdown begins smoking lightly and occasional light smoke during test cell run. All usual suspects checked out, external check valves, oil flows 110cc, no blocked scavenge struts, gearbox scavenge checks good, no oil pooling in exhaust. Opened turbine and found oil bypassing sump cover seals seal onto PT wheels clearly causing smoke. All turbine seal clearances including sump cover checked, well within limits. I know carbon lock up on R engines is common. Has anyone also noticed occasional smoke. We are not that familiar with R engines. Could the higher compressor discharge pressures on these engines mess with seal function.

[Gomer Pylot]

After 9 years of sitting, the seals may have deteriorated. You may need new seals.

[iChris]

Nine years, that's a long time, even if they followed the preservation procedures called for in the maintenance manual. As stated in Gomer Pylot's post, seals are consistent with the problem you're having per the maintenance manual. Also note light smoke being normal.

 

See item# 57

 

(click photo to enlarge)

 

 

 

 

Model 250-C20R/1 is similar to the 250-C20B except for increased performance, a new compressor, addition of an electronic power turbine (N2) overspeed protection system and an on-speed 1st stage turbine wheel internal energy absorbing ring.

Edited February 17, 2016 by iChris