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Learn about the important functions of carburetors in aero engines, including vaporizing fuel and mixing fuel and air. Understand carburetor mixture ratios and the dangers of carburetor icing.
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Aero Engines 9.03 Carburetor, Mixture, and Icing References: FTGU pages 61-68
Review • This type of fuel system relies on fuel pump to keep fuel flowing to the engine. • What is vapour lock? • What are the 4 functions of oil?
9.03 Carburetor, Mixture, and Icing MTPs: • Functions of the Carburetor • Parts of a Carburetor • Mixture • Carburetor Ice
Functions of the Carburetor Carburetor is the heart of an engine. The two key functions of the carburetor are: (1) Vaporize the Fuel (2) Mix Fuel and Air
Mixture Carburetor Mixture Ratios • Fuel-Air mixture • Running mixture • 1:8 • Best power mixture • 1:14 • Chemically correct mixture • 1:15 • Lowest fuel consumption mixture • 1:18 • Leanest running mixture • 1:20
Mixture Control • Fuel-Air mixture • Rich: lots of fuel • Lean: little fuel • Too rich a mixture may lead to: • Unburned fuel in exhaust (wasteful) • Fouled spark plugs • Rough running engine • Loss of power • Engine failure • Too lean a mixture may lead to: • Overheating • Back-firing • Detonation • Rough running engine • Loss of power • Engine failure
Carburetor Ice • Ice can form in the carburetor and will restrict air flow to the engine, resulting in: • Loss of Power • Rough Running Engine • Total Engine Failure • Ice can READILY form in the carburetor in CLEAR AIR with ambient air temperatures from -5 to +30 degrees Celsius, depending on the humidity of the air
Icing – Dangerous Conditions Serious Icing - cruise or climb power Moderate Icing - cruise power or serious icing - glide power Serious Icing - glide power Light Icing – cruise or glide power
Carburetor Heat Use of Carb-heat and its Effects on Mixture
Confirmation • What are the 2 key functions of the carburetor? • What is the best power mixture ratio? • Under what conditions can carburetor icing occur?