PLANE & PILOT - April 2002

Warmer weather and higher humidity make life miserable for y our carburetor

By Bill Cox

It happens several times a year: A pilot launches from Ft. Lauderdale or Atlanta or Nashville on a warm spring day in seemingly good weather, climbs to a moderate altitude, sets up normal cruise and inexplicably loses engine power. If the pilot is lucky, power may return automatically as the airplane descends, even without corrective action. If not, he or she may ride the airplane into an emergency landing or, worse, without ever understanding the source of the trouble. Carburetor ice can be a stealthy killer that sneaks up on a pilot, robs the engine of power so gradually that it's hardly noticeable and often melts and leaves no trace of its presence if the power loss results in an accident. Perhaps worst of all, statistics suggest many pilots misunderstand the nature of the beast, despite training that warns carb ice is nothing if not insidious.

An NTSB study in the late '80s revealed some 360 accidents induced by carburetor ice, resulting in 40 fatalities and 160 injuries. (In this case, "carburetor ice" was a generic term describing all inductionsystem accidents, whether logged in carbureted or fuel-injected airplanes.) Fully 74% of those carb-ice accidents occurred in clear air without visible moisture. Those statistics are all the more surprising in view of the fact that the large majority (read that as "all") of those accidents could have been prevented by the simple expedient of applying carburetor heat. No matter how simple the fix, Cessna was so concerned with the carb-ice problem that the company made a major corporate decision in the early '90s to install only fuel-injected engines in its updated line of piston singles, the Skyhawk, Skylane and Stationair...

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