On aircraft equipped with leading edge deicing boots, a check of their function should be completed before any flight into icing conditions. A long time back, when I was flying a KingAir 100, we encountered similar icing conditions to those experienced in the Roselawn (Chicago) accident during approach into Milwaukee, WI. There was approximately 1/2 inch of ice on the unprotected surfaces as we made our approach. I was hand flying the aircraft and we were cycling the boots as per the KingAir manual. When I called for full flap on final approach (IMC), the aircraft began to pitch up as the flaps extended. I hit the forward stop on the elevator control, and the pitch was approaching 10 degrees nose up and increasing. I called for flaps up and slowly started increasing power. Fortunately the pitch up stopped and I was able to regain control. We retracted the flaps and continued our approach for a flapless landing. While I can't recall the exact number (it all happened pretty fast!), I believe I carried 140 to 150 kts down to landing to keep control.
When we got to the FBO, I climbed out and found that there was at least 1 inch of ice on the leading edge of the left horizontal stab. A function check showed that the boot was not inflating. After that, we had our maintenance guy stand outside the aircraft after engine start at home base and he did a visual check of the boot function. Not a perfect solution, but one more way to reduce the risk.
Last edited by Safety Guy; 21st Jan 2006 at 18:41.