Aircraft Engine Idle Speed

Questions and Answers

What is a desirable characteristic of engine idle speed?

It should be smooth and free of vibration (correct)

It should be high enough to maximize power output

It should be low enough to save fuel

It should be adjustable by the pilot

Why is it important to maintain a certain idle speed?

To reduce engine noise

To improve engine responsiveness

To increase engine power output

To maintain idling oil pressure and prevent engine stoppage (correct)

What is a consequence of insufficient idle speed?

Reduced engine power output

Engine stoppage in flight (correct)

Engine overheating

Engine vibration

What should happen when the throttle is closed in flight?

The engine should idle smoothly and maintain oil pressure Signup and view all the answers

Why may engine idle speed vary among different engines?

Because of differences in engine design and application Signup and view all the answers

What should you do after adjusting the idle mixture?

Run engine up to approximately 2000 RPM Signup and view all the answers

Why do you need to run the engine up to approximately 2000 RPM after adjusting the idle mixture?

To clear the engine of excess fuel Signup and view all the answers

What is the primary purpose of running the engine up to 2000 RPM after adjusting the idle mixture?

To obtain a correct idle speed Signup and view all the answers

What is a consequence of not running the engine up to 2000 RPM after adjusting the idle mixture?

The engine may not idle correctly Signup and view all the answers

What is the recommended RPM to run the engine after adjusting the idle mixture?

2000 RPM Signup and view all the answers

Where does ram air to the engine enter the induction system?

Through an opening in the forward part of the lower engine cowling nose cap Signup and view all the answers

What is the purpose of the valve in the induction airbox?

To permit air from an exhaust heated source to be selected in the event of carburetor icing or filter icing Signup and view all the answers

How are the intake pipes attached to the intake manifold?

With a hose and clamp Signup and view all the answers

Where is the carburetor located?

On the lower side of the engine Signup and view all the answers

What happens to the filtered air from the induction airbox?

It is directed to the intake manifold Signup and view all the answers

Study Notes

Engine Idle Speed

Idle speed may differ among various engines
Smooth engine idling is required, with minimal vibration
The idle speed should be high enough to:
- Maintain idling oil pressure
- Prevent engine stoppage in flight when the throttle is closed

Engine Idle Speed

Engine idle speed can vary among different engines.
An engine should idle smoothly, without excessive vibration.
The idle speed should be high enough to:
- Maintain idling oil pressure.
- Prevent engine stoppage in flight when the throttle is closed.

Idle Mixture Adjustment

After adjusting the idle mixture, run the engine up to approximately 2000 RPM.
This is done to clear the engine of excess fuel and obtain a correct idle speed.

Air Induction System

Ram air enters the engine through an opening in the forward part of the lower engine cowling nose cap.
The air is filtered through a filter located at the opening in the nose cap.
The filtered air is directed to the inlet of the carburetor, mounted on the lower side of the engine.
In the carburetor, fuel is mixed with the air to create a fuel-air mixture.
The fuel-air mixture is distributed to each cylinder by separate intake pipes attached to the intake manifold.
The intake pipes are attached to the intake manifold with hose and clamps, and to the cylinder with a two-bolt flange sealed with a gasket.

Anti-Icing System

The induction airbox contains a valve operated by the carburetor heat control in the cabin.
The valve permits air from an exhaust-heated source to be selected in case of carburetor icing or filter icing.