my endless series of questions for the folks on here.
My last flordia trip at FL25, encountered some light rime icing and turned all the deicing equipment on. Engine inlet heat on and igniters came on as well. I didn't really get excited much since it was light rime and really wasn't collecting fast at all. Plus, i thought in about 5 minutes or so, i would be out of it (not sure why, i guess i was over Georgia and its warm in Georgia, lol). Well after about 10 minutes i was still in it and there was about an 1/8 inch of ice on the leading edge so i cycled the boots on one cycle. Another 5 minutes goes by and I am still in this light icing and all of a sudden the left engine started an imbalance and a slight vibration. I recognized this imbalance right away, as in the past our 681 experienced this once when we were in moderate icing and had one blade heat failure and it setup the same type of feeling i was experiencing here (the other 2 blades in that 681 were working fine we found out on the ground). So i immediately requested a climb to FL27 and i was out of the icing at about FL26. I flew for about 8 minutes out of the icing at FL27 but the imbalance was still there and not going away. So i thought i better head down hill to warmer air and get this imbalance gone. At about FL17 the imbalance was gone and so i went back up to FL20 the rest of the way problem free-sort of i still have a small comm issue).
Got on the ground and all blades both inboard and outboard of the prop heat are working great, so i couldn't find any failure?
Have any of you ever had any experience like this before in your turbines?
Couple of other things i may should or could have done.
1.) Turned off the prop sync perhaps? Although i didn't think it was doing anything abnormal to either engine?
2.) I was was 97 percent cruise, i thought of quickly bringing the conditioning levers up to 100% and them back down to 96%, but wasn't sure this would do anything that was sticking on that prop, plus i didn't want to abuse this turbine engine? Piston planes we used to cycle the props in moderate icing and it would help out quite a bit to shed ice.
Inspecting these props again tonight, They were overhauled and new prop heat's were installed last winter, however, these props were sand blasted a year ago at Peoria runways last winter when it was 20 below zero and they sanded those runways back then. In my training, i did two heavy beta stops back then on those runways and the new looking propellers have sand blasting on them. The only thing i am thinking now is to polish these prop boots up real nice with some PBS and get them so one would need sunglasses to look at them directly?
Do any of you know what the best material would be to polish these babies up so ice can't bridge or build up on them- anything better than Pbs? Any experiences with prop imbalances from anyone? Can't be good for the engines i would imagine operating them for a longer time period of imbalance i would guess?