Chapter 5: Induction Systems

1. Air Intake

2. Induction air filter

3. Fuel metering system

4. Induction manifold

1. Paper Type

2. Flock Type

3. Polyurethane Foam

Fuel Evaporation Ice

Throttle Ice

Impact Ice

Also known as Carburetor Ice

In a carburetor, as fuel is released into the airstream, it turns into a vapor and absorbs heat from the surrounding air. This can cause a drop in air temperature and in some cases, this loss of heat is enough to cause the moisture in the air to condense and freeze.

Optimum weather conditions for carburetor ice to exist when the outside air temperature is between 30 and 40 degrees F and the relative humidity is above 60%

Throttle ice forms on the downstream side of a throttle, or butterfly valve, when it is ina partially closed position. Air flowing across and around the throttle valve creates an area of low pressure on the down-stream side. This has a cooling effect on the fuel/air mixtur, which can cause moisture to accumulate and freeze on the downstream side of the butterfly valve.

Impact ice is caused by visible moisture striking an aircraft and then freezing. The air intake and air filter are the areas most susceptible to impact icing.

Decrease in engine power

1. Excessive use increases the chance of dirt and foreign material entering the engine

2. If placed in “hot” position on engine start-up, damage to a carburetor heat air box could result if the engine backfires

3. Fuel/air mixture becomes richer and causes a noticible loss in power

4. High intake air temperatures from carb heat can lead to detonation during high power settings

Cold position

1. Air inside a heater muff surrounding a hot exhaust pipe become heated then directed to a carburetor air box

2. An carburetor air box alternate air supply that can draw air from the main intake or from inside the cowling

3. Fuel-injected engines use an alternate air door that lets warm unfiltered air flow into the induction system

Supercharger

Single stage, single-speed supercharger

Single stage, two-speed supercharger

1. Low Speeds - also known as a low blower setting has a impeller gear ratio of 8:1

2. High Speeds - alos known as a high blower setting has a impeler gear ratio of 11:1

Exhaust gases

Critical altitude

The friction caused by high rotation speeds, exhaust gases flowing through the turbine, and the compression air intake all causes heat in the turbocharger so a continuous flow of engine oil must be poured through the bearing housing to cool and lubricate the bearings

Intercooler

A wastegate

1. Manually through controls in the cockpit

2. Automatically through either:

• A wastegate actuator that uses a spring to hold open the wastegate and oil pressure that closes the wastegate

• Absolute Pressure Control

• Pressure-Ratio Controller

Sea level-boosted engines

1. Exhaust bypass valve assembly

2. Density controller

3. Differential pressure controller

4. Turbocharger

Exhaust Bypass Valve Assembly

Density Controller

Differential Pressure Controller

Differential Pressure Controller

Boot Strapping

It can cause damage to the turbocharger, intake manifold, pistons and cylinders

Overshoot

Fuel atomizing

Cabin Pressurazation

Even fuel distribution

Power Recovery Turbine

A system which enables an engine to recover energy from the velocity of exhaust gases that would otherwise be lost.

Ram Recovery

A divergent shape

Pressure in increased and velocity is decreased

Primary airflow

• responsible for 20-30% thrust

Secondary Airflow

• also known as bypass airflow and used for cooling

Convergent inlets designed specifically for obtaining high aerodynamic efficiency when stationary or in slow flight typically used on helicopters and slow moving aircrafts

Oil Pressure Guage

Supercharger

Turbocharger

Prone to icing

uneven fuel distribution

uneven atomizing