FROM THE LEFT SEAT

 

     Another month has come and gone, not much in the way of flying weather, but good weather for polar bears!  I hope all survived the cold weather.  REMEMBER, THAT YOUR DUES ARE DUE THIS MONTH!!!  WE NEED TO HAVE EVERYONE PAID SO WE CAN GET THE UPDATED LIST TO THE WEB MASTER.  ALSO THIS WILL BE YOUR LAST NEWSLETTER, UNLESS YOUR DUES ARE PAID.

 

     Talking about the cold weather, even though we live in a warm state, we still need to be mindful of Carburetor icing.  This nasty problem can sneak up on you when you least expect it, and it can even happen on a 90 degree day.  Carburetor heat is designed to pre-heat induction system air before it reaches the carburetor.  The purpose of carburetor heat is to prevent the formation of carburetor ice by keeping the air/fuel mixture in the carburetor venturi above  freezing, it also produces enough heat to melt ice that has already formed.  Carb heat should be checked before every flight as part of your pre-flight checks, as well as periodically during flight when ever the conditions are right for the formation of ice.  Anytime carb ice is detected, you should apply full carb heat, and leave it on until you are certain all of the ice has been removed.  Use of the carb heat will also reduce engine power output by at least 15%.  This is due to the fact that the heated air entering the engine is less dense than the cooler air, and it richens the fuel/air mixture.  If ice is present when the carb heat is applied, there will be an immediate drop in engine r.p.m., followed by a gradual increase in rpm as the ice is melted.  This can last anywhere from 30 seconds to several minutes.  Also, as the ice is melted, the engine will run rough as the ice is ingested into the engine.  The engine will run smoother once the ice has been removed, also if the carb heat is applied, and the engine stays at the lower rpm, there was no ice present.  Those of you that have constant speed props, the rpm will stay constant, but you will notice a change in your manifold pressure.

 

     Whenever the throttle is closed in flight, the carb heat must be applied because the engine cools very rapidly, and the engine becomes susceptible to icing.  Also it should be left full "on" for the duration of closed throttle, or low power operation.  Since carb heat reduces the  power output of the engine and increases it operating temp, you should not use it for high power operation such as take off or climbing.  Even at normal operations, such as cruise, you should avoid the use of carb heat except as necessary to remove carb ice, or to prevent its occurrence.