I had mixed results with Evade in a round trip from Portland to Southern California last week. There was weather on the flight down, but it looked like 19,000 would top it all. I expected a bit of light ice on the climbout but there was none. On top at 19,000 I began to get into a few tiny buildups which were a little bumpy. 20,000 solved that problem. Darkness fell at the halfway point, over the middle of the Sierra Nevada just west of Lake Tahoe. (METAR at South Lake Tahoe way below: 1/4 mile, snow, freezing fog - is there anyone that honestly can say they would not want a parachute at that moment?). Tops got higher so I went through the hassle of putting the mask on and got on up to 230. Just barely on top and very cold at -30C. Airliners descending into Sacramento were getting ice between 20,000 and 14,000.

Once again the status tops rose to my altitude. At least I don't have to worry about ice: it's too cold ... Right? Wrong! In my flashlight I clearly see the white frost on the leading edges and the IAS drops a bit. I push the Evade button .... the red FAIL light come on! &*%#! So I climb all the way to 250. Fortunately that is on top the rest of the way.

After I leveled off I rebooted the Evade controller by resetting the 3 amp breaker. This time the system booted up and stayed on without problems. It cleared the frost too. I don't know why it failed the first time.

The next incident happened on the return trip. I cruised relatively low (10,000) to minimize the strong headwinds. Over Bakersfield I was in and out of small CU's. They weren't very bumpy, but they had some ice. A couple thousand foot climb would have topped the little buildups and it was clear above. Feeling in no danger I decided to stay where I was, turn on Evade, and see how it did. After 10 minutes of this, the right wing was clear, the left wing was clear except for an area about 12 inches long between the cuff and the stall warning tab. The left horizontal still had ice on it, top and bottom, as best I could see. The right horizontal seemed to have ice on the bottom but not the top (again, it's a little hard to see the tail - I'm going to carry binocs now for that purpose). IAS had dropped from 150 to 125 or so, and the airplane was a little mushy. In the past I have found that you only lose a few knots from modest ice on the unprotected surfaces. It would seem that some of the heaters (or portions of the heaters) were not heating up enough. Yet the cockpit lights indicated that the system was working properly. The ice that did accumulate was rough, jagged, uneven rime.

The third incident occurred the next day with light icing on the descent into the Portland area from 16,000 feet. The system worked perfectly and I was quickly clear of the icy region.

I have not had an opportunity to discuss these issues with Kelly.

__________________
Art Schwalge
Columbia 400
N4468F