Aero Engines 9 03 Carburetor Mixture and Icing

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

Functions of the 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

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

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

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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