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Aero Engines

9.03 Carburetor, Mixture, and Icing References: FTGU pages 61-68

Review

1.  This type of fuel system relies on fuel pump to keep fuel flowing to the engine.

2.  What is vapour lock?

3.  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

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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

The Carburetor

Parts of the Carburetor

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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 Controls

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

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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

Carburetor Ice

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

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Dangerous Conditions

Carburetor Heat

Use of Carb-heat and its Effects on Mixture

Confirmation

1.  What are the 2 key functions of the carburetor?

2.  What is the best power mixture ratio?

3.  Under what conditions can carburetor icing occur?

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Full rich…