52 RCACSGround School

EnginesPO 407 EO 2

“Cooling, Fuel and Lubrication Systems”

Introduction

Teaching PointsReview

Reference: FTGU Chapter 3

Section A Pages 57-59Section B Pages 59-61

Cooling SystemIn an internal combustion engine, fuel is

burned, causing much heat. This heat is absorbed partly by all the metal engine parts. Some method of cooling must occur. Air-cooled engines are most common, some use antifreeze liquid cooling.

Methods of Cooling FINS:

Metal plates on the outside of the cylinders that increases the surface area exposed to the air.

COWL FLAPS: They vary the size of the opening at the

front of the engine cowling. They control the amount of air entering the engine, so controlling the amount of DRAG produced.

COOLING FANS: Powered by crankshaft, they increase

airflow over the engine. AUGMENTOR TUBES:

Jet pumps powered by escaping exhaust gases, they increase airflow over the engine.

Lubrication SystemLubrication oil has 4 important functions:

Cooling: Carries away excessive heat generated by the engine.

Sealing: Provides a seal between the piston rings and cylinder walls,

preventing "blow-by" loss of power and excessive oil consumption.

Lubrication: Prevents wear and tear of metal parts by maintaining a film to

reduce friction.

Flushing: Cleans and flushes engine interior of contaminants that enter

of are formed during combustion.

REQUIREMENTS OF THE OIL VISCOSITY:

Resistance to flow. HIGH FLASH POINT:

Temperature at which to oil burns. LOW CARBON CONTENT:

Less carbon, less deposit in engine. LOW POUR POINT:

Temperature at which oil solidifies.

Pour Point Test

METHODS OF LUBRICATIONDRY SUMP (FORCED FEED)

Oil is injected into the crankcase through hoses by pump. Oil reservoir is a tank separate from the engine.

WET SUMP (SPLASH)Oil is kept in a pan below the engine. Crankshaft

sits in oil and churns it into a heavy mist that covers all parts of the engine.

TYPES OF FUEL SYSTEMSGRAVITY FEED:

Used in high-wing aircraft (when fuel tanks are above engine). Gravity does the work.

FUEL PUMP: Used in low wing aircraft (when tanks are not

above engine). Electric and/or engine driven pump does the work.

COMPONENTS OF THE FUEL SYSTEM

Fuel Tanks:carry aircraft’s fuelvary in size and shapeusually located in the wings

Fuel Selector Control:permits the pilot to select which tank he wishes to

draw fuelFuel Line and Filters:

connecting the fuel tanks to the carburetor - fuel is filtered by one or several filters.

Questions?

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