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Pilot's Handbook of Aeronautical Knowledge
Aircraft Systems
Engine Cooling Systems

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Pilot's Handbook of Aeronautical Knowledge



Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making




Wet-sump oil system.
Figure 6-17. Wet-sump oil system.

The oil temperature gauge measures the temperature of oil.
A green area shows the normal operating range and the red
line indicates the maximum allowable temperature. Unlike
oil pressure, changes in oil temperature occur more slowly.
This is particularly noticeable after starting a cold engine,
when it may take several minutes or longer for the gauge to
show any increase in oil temperature.

Check oil temperature periodically during flight especially
when operating in high or low ambient air temperature. High
oil temperature indications may signal a plugged oil line, a low
oil quantity, a blocked oil cooler, or a defective temperature
gauge. Low oil temperature indications may signal improper
oil viscosity during cold weather operations.

The oil filler cap and dipstick (for measuring the oil quantity)
are usually accessible through a panel in the engine cowling. If
the quantity does not meet the manufacturer's recommended
operating levels, oil should be added. The AFM/POH or
placards near the access panel provide information about
the correct oil type and weight, as well as the minimum and
maximum oil quantity. [Figure 6-18]

Engine Cooling Systems

The burning fuel within the cylinders produces intense
heat, most of which is expelled through the exhaust system.
Much of the remaining heat, however, must be removed, or
at least dissipated, to prevent the engine from overheating.
Otherwise, the extremely high engine temperatures can lead
to loss of power, excessive oil consumption, detonation, and
serious engine damage.

Always check the engine oil level during the preflight inspection.
Figure 6-18. Always check the engine oil level during the preflight

While the oil system is vital to the internal cooling of the
engine, an additional method of cooling is necessary for the
engine's external surface. Most small aircraft are air cooled,
although some are liquid cooled.

Air cooling is accomplished by air flowing into the engine
compartment through openings in front of the engine
cowling. Baffles route this air over fins attached to the engine
cylinders, and other parts of the engine, where the air absorbs
the engine heat. Expulsion of the hot air takes place through
one or more openings in the lower, aft portion of the engine
cowling. [Figure 6-19]