There are two main types of aircraft oil systems: wet-sump and dry-sump. A wet-sump system contains oil in a sump that is integral to the engine, while a dry-sump system contains oil in an external tank. Both systems circulate oil through pumps, but a dry-sump uses additional scavenge pumps to return oil to the external tank. Pilots monitor oil pressure and temperature gauges during flight to check the system and identify any issues like low oil quantity or blocked lines.

1. AIRCRAFT OIL SYSTEMS
2 TYPES
WET SUMP
DRY SUMP

2. SIMPLE FACTS
• Two Systems:
• Wet-sump system
• Dry-sump system
• The difference in the systems can be remembered as if the engine were off
• If it didn't have oil in the engine, it would be dry or a dry sump system,
where a separate tank was used; but if the engine would be wet with oil, then
it is a wet sump system with the sump being integral to the engine.

3. SIMPLE FACTS
• On light aircraft the oil filler cap and dipstick are usually accessible
through a panel in the engine cowling
• The dipstick is used for measuring engine oil quantity (sometimes it
could be a sightglass)
• If the quantity does not meet the manufacturer's recommended
operating levels, oil should be added, this also refers to the AMM
• The type of oil required may vary on numerous atmospheric and
operation conditions, as stipulated by the aircraft operations manual

4. SIMPLE FACTS
Placards near the access panel provide information about the
correct oil type and weight, as well as the minimum and
maximum oil quantity
The system is monitored through pressure and temperature
gauges. The loss of engine oil pressure would lead to engine
vibrations, RPM would decrease, and the engine would eventually
seize
(Note Viscosity = the ability of a liquid to resist flow)

5. SIMPLE FACTS
Wet-Sump:
Oil is carried in a sump, which is an integral part of the engine
The main component is the oil pump, which draws oil from the
sump and routes it to the engine possibly through an oil cooler.
After the oil passes through the engine, it returns to the sump
In some piston engines, additional lubrication is supplied by
the rotating crankshaft, which splashes oil onto portions of the
engine.

6. SIMPLE FACTS
Dry-Sump:
Oil is contained in a separate tank, and circulated through the engine by pumps
These tanks are always larger than the oil it is meant to contain to compensate for
thermal expansion
An oil pump also supplies oil pressure in a dry-sump system, but the source of the oil is
located external to the engine in a separate oil tank
After oil is routed through the engine, it is pumped from the various locations in the
engine back to the oil tank by scavenge pumps (Normally bigger than the delivery pump)
Dry-sump systems allow for a greater volume of oil to be supplied to the engine, which
makes them more suitable for very large reciprocating engines
Most jet engines will consist of a dry sump design.

7. SIMPLE FACTS

8. SIMPLE FACTS
Oil Pressure Gauge:
The oil pressure gauge provides a direct indication of the oil system
operation
It ensures the pressure in pounds per square inch (psi) of the oil supplied
to the engine
Green indicates the normal operating range, while red indicates the
minimum and maximum pressures.
There should be an indication of oil pressure during engine start

9. SIMPLE FACTS
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

10. SIMPLE FACTS
When the pilot checks oil temperature periodically during flight
especially when operating in high or low ambient air temperature (i:e
The Gulf or Iceland)
High oil temperature indications may signal:
Blocked oil line or cooler (A cooler might look like a car
radiator)
low oil quantity (leading to possible engine failure)
Defective temperature gauge
High oil temperatures can lead to metal on metal contact as
viscosity decreases
Low oil temperature indications may signal improper oil viscosity

11. SIMPLE FACTS
Conclusion:
Oil systems reduce friction on moving parts, create better
seals, reduce and remove heat, carry away contaminants and in
some cases, run other systems
Many systems have pressurised sumps and a pressurised oil
tank to ensure a constant head pressure to the lubrication pump
to prevent pump cavitation at high altitudes
Oil consumption is relatively low in a gas turbine engine
compared to a piston-type engine. (Yes I am surprised at that)