Club Homepage Forums Classified Ads Buy & Sell - Everything But Airplanes The "Lead Problem": Is it That Big a Deal?

We 150 guys get used to that. I've seen 152 pilots nearly panic from carb icing because they so seldom run into it that they think something broke on the engine, or somethings going bad.

I had that situation once. I was flying with a passenger. Upon entering downwind, I turned on carb heat then reduced power to 1500 rpm. Suddenly, the engine started shaking like the devil. The passenger panicked and asked what was going on. I told him I didn't know, and made a short approach from downwind to the threshold (uncontrolled field). By the time I got to the numbers, the engine smoothed out and I made a normal landing. Afterward, I ran the scenario through my mind and suspected that carb ice had developed during the long descend. Although the engine rpm was still in the green zone during the descend, it probably was wind-driven and not working that hard to produce enough heat.

During my instrument training with my instructor I took off and we are in visible moisture (IMC) at 500 ft AGL. During the climb out with full power the engine began running rough (my butt started sucking on the seat) I added carb heat and it took almost two minutes to clear. The temp was about 40 degrees. That was interesting. The conditions were just right at the wrong time.... I frequently checked the carb heat during that flight and no other icing was detected.

Will

You should always use carb heat when the engine is still making power, prior to entering the pattern. When the engine is throttled back it may not produce enough heat in the exhaust muff to be effective if you have an accumulation of carb ice.

If you are suspicious of carb ice you can "clear" the engine, that is add some power to generate a little heat. Back the bad old days of Cubs, which were real ice makers, we were expected to perform power off landings, (to a spot) and when things weren't going right we would "clear" the engine. The instructor or examiner would sometimes let you get away with it, often with a caustic comment about how if the engine were to quit you should be able to make the runway anyway.

George