06. Piston Engine Lubrication and Cooling Flashcards
1
Q
The primary function of oil in an engine is to reduce
____ and ____
A
- Friction
- Wear
Pg 141
2
Q
The 4 secondary functions of engine oil are
A
- Cooling
- Cleaning
- Protection
- Hydraulic
Pg 141
3
Q
Which 2 readings values can be monitored to determine the condition of an engine
A
- TEMPERATURE - Oil temperature
- PRESSURE - Oil pressure
Pg 141
4
Q
What is viscosity
A
RESISTANCE OF FLUID to FLOW
Pg 142
5
Q
High viscosity oil makes the engine MORE or LESS difficult to turn over
A
MORE
Pg 142
6
Q
Low viscosity oil makes the engine MORE or LESS difficult to turn over
A
LESS
Pg 142
7
Q
What is the primary benefit of a high viscosity oil
A
GUARANTEES GOOD FILM
Guarantees a good film on the bearings
Pg 142
8
Q
The higher the oil number, the HIGHER or LOWER the viscosity
A
HIGHER
HIGHER = HIGHER, lower = Lower
Pg 142
9
Q
What are 5 properties aero engine oil must achieve
Sticky Sludge Corrodes Materials and then Evaporates
A
- Sticky - VISCOSITY - Maintain viscosity over a wider range of temperatures and pressures
- Sludge - SLUDGE - Discourage sludge formation
- Corrodes - CORROSION - Inhibit corrosion
- Materials - MATERIALS - Not react with materials
- Evaporates - EVAPORATION - Low evaporation point
Pg 142
10
Q
Compound oil is oil containing what
A
ADDITIVES
Pg 142
11
Q
Oil containing additives is known as what
A
COMPOUND OIL
Pg 142
12
Q
Oil used in new engines to reduce running-in time is known as what
A
STRAIGHT OIL
Pg 142
13
Q
Straight oil is used specifically for what, and has NO or ADDITIONAL additives
A
- RUNNING IN new engines
- NO ADDITIVES
Pg 142
14
Q
What should an aircraft operator do with oil according to the engine manufactorer
A
CHANGE THE OIL
Change oil according to the schedule
Pg 143
15
Q
Blue or grey smoke in the exhaust is a sign of what
A
EXCESSIVE OIL BURNING
Pg 143
16
Q
Excessive oil burning is identified by smoke of what 2 colours in the exhaust
A
- BLUE
- GREY
Pg 143
17
Q
What are the 2 methods of storing engine oil
A
- DRY sump
- WET sump
Pg 144
18
Q
Oil held in a tank mounted remotely from the engine is a ____ sump system
A
DRY
Pg 144
19
Q
Oil held in the bottom of the crankcase is a ____ sump system
A
WET
Pg 144
21
Q
Dry Sump System
In a dry sump system, how is oil drawn into the engine
A
ENGINE DRIVEN PUMP
(EDP)
Pg 145
22
Q
Dry Sump System
What is the purpose of a Pressure Relief Valve
A
REGULATES SYSTEM PRESSURE
Pump provides more oil pressure than necessary.
Ensures that sufficient pressure available under extreme conditions
Pg 146
23
Q
Dry Sump System
Highly loaded points such as big end bearings that require high pressure are provided oil at around ____ to ____ PSI
A
60 - 70 PSI
4 - 5 bar
Pg 146
24
Q
Dry Sump System
The camshaft is fed by HIGH or LOW pressure oil
A
LOW
Via a pressure-reducing valve
Pg 146
25
# Dry Sump System
What is the purpose of a *scavenge pump*
PUMP OIL to OIL TANK
| Via the oil cooler
## Footnote
Pg 146
26
# Dry Sump System
How is oil pumped back to the oil tank
SCAVENGE PUMP
## Footnote
Pg 146
27
# Dry Sump System
Oil returns from the engine via the ____ line and ____ valve
1. Scavenge line / Oil return line
2. Non-return (check) valve
## Footnote
Pg 147
28
# Dry Sump System
What is the purpose of the *de-aerator* plate
SEPARATE OUT AIR BUBBLES
## Footnote
Pg 147
29
# Dry Sump System
What component is used to *seperate out air bubbles* from fuel returning to the tank
DE-AERATOR PLATE
## Footnote
Pg 147
30
# Dry Sump System
What is used in the tank to prevent fluid from sloshing around
BAFFLES
## Footnote
Pg 147
31
# Dry Sump System
What is the purpose of a *hot well*
HOT OIL RETURN on startup
## Footnote
On startup, oil is viscious. Oil is pulled in to the engine first from the hot well.
As the oil returns to the tank, it has been warmed by the engine and drops into the hot well
This ensures that warmer oil is returned back to the engine whilst the surrounding oil in the tank is gradually heated to temperature
Pg 147
32
# Dry Sump System
The coarse filter fitted before the *pressure* pump is know as a SUCTION or SCAVENGE filter.
The coarse filter fitted before the *scavenge pump* is known as a SUCTION or SCAVENGE filter.
1. SUCTION
2. SCAVENGE
## Footnote
Pg 147
33
# Dry Sump System
What component is used to remove ferrous particles from the oil in the return line
MAGNETIC PLUGS
| Chip Detectors
## Footnote
Ferrous particles from the engine or gearbox are caught by magnets
Pg 148
34
# Dry Sump System
Oil pumps are driven by the ____ and normally through the use of ____ (mechanical component).
The pump speed varies with ____
1. Engine
2. Spur gears
3. Engine RPM
## Footnote
Pg 148
35
With *higher* RPM speeds, how is pump pressure regulated
PRESSURE RELIEF VALVE
## Footnote
Pg 148
36
# Dry Sump System
With *high* RPM speeds, a *low* oil pressure may indicate what
WORN OIL PRESSURE PUMP
## Footnote
Pg 148
37
# Dry Sump System
How does the PRV operate when there is *excessive pressure* detected from the EDP.
SPRING LOADED VALVE
## Footnote
Spring loaded valve opens which allows oil to be moved back to the suction side of the pump
Pg 148
38
# Dry Sump System
What component is fitted to ensure that oil continues to lubricate the engine if the *pressure filter* becomes blocked or clogged
BY-PASS VALVE
## Footnote
Pg 148
39
# Dry Sump System
Between which 2 system components is the *oil cooler* fitted
SCAVENGE PUMP (& magnetic chip detector) < > OIL TANK
| Fitted in the scavenge line
## Footnote
Pg 149
40
# Dry Sump System
What is the purpose of an *anti surge valve*
BY-PASS AIR COOLER
| Allows oil to bypass the cooler when cold and viscious
## Footnote
Pg 149
41
# Dry Sump System
The *Oil temperature gauge* measures the oil temperature after the ____ and before the ____
1. Oil cooler (& oil tank / hot well)
2. Pressure pump
## Footnote
Pg 151
42
# Dry Sump System
The *oil pressure gauge* measures oil pressure at which point in the system
OUTLET of the PRESSURE PUMP
## Footnote
Pg 151
43
# Dry Sump System
Oil pressure and temperature are inextricably linked.
For a given RPM, *cold* oil will indicate a HIGER or LOWER pressure than oil operating at a normal temperature
HIGHER
## Footnote
Pg 151
44
# Wet Sump System
What is the core difference between a *wet sump* and a *dry sump* system
OIL TANK vs OIL SUMP
## Footnote
Dry sump system uses an oil tank to collect and hold oil
Wet sump system collects oil in the engine sump
Pg 153
45
# Wet Sump System
What is an inherent risk of a *wet sump* system
INVERTED FLIGHT
(oil starvation)
| Oil disperses around engine during inverted flight
## Footnote
Oil disperses around the system during inverted flight.
This can quickly lead to oil starvation
Pg 153
46
# Wet Sump System
What is the name given to the method of lubrication in whcih in the crankshaft cycles through the oil in the sump
SPLASH LUBRICATION
## Footnote
Pg 152
47
# Wet Sump System
What are 2 disadvantages of a *wet sump* system in regards to high RPM and splash lubrication
1. EXCESSIVE OIL - High RPM can cause excessive oiling
2. NOT COOLED or FILTERED
## Footnote
Pg 153
48
After shutdown, when should the oil level be checked in;
1. Dry Sump System
2. Wet Sump System
1. IMMEDIATELY
2. 20 Mins
## Footnote
Pg 153
49
*Worn piston rings* and *worn piston heads* will result in FASTER or SLOWER oil consumption
FASTER
## Footnote
Worn rings and worn piston head allows oil to get past the piston skirt, leading to greater oil consumption
Pg 154
50
*Low viscosity* oil will lead to GREATER or LOWER oil consumption
GREATER
## Footnote
Low viscosity oil can eascape past the oil control ring on the piston
Pg 154
51
When should the *oil level* in the reservoir be checked
BEFORE EVERY FLIGHT
## Footnote
Pg 154
52
What will lead to an *increase* in oil temperature and a *decrease* in oil pressure
LOW OIL QUANTITY
## Footnote
Low oil quantity means less oil in the system.
This means it passes back through the system more quickly, having less time to be cooled, subsequnetly increasing in temperature and lowering the pressure
Pg 154
53
Generally, a *decrease* in oil temperature will lead to a DECREASE or INCREASE in oil pressure
INCREASE
## Footnote
Colder oil means more viscious. If more viscious, it does not pass through the system as easily.
Oil moving less freely will build system pressure
Pg 154
54
What are 2 methods of cooling *piston engines*
1. AIR
2. LIQUID
## Footnote
Pg 156
55
# Liquid Cooled System
What is a *benefit* and a *disadvantage*
1. LESS DRAG - Benefit
2. INCREASED WEIGHT - Disadvantage
## Footnote
Less drag as there are no air intakes required
Increased weight due to the extra liquid required
Pg 156
56
# Liquid Cooled System
How does the liquid diserpate heat back to the atmosphere
RADIATORS and RAM AIR
## Footnote
Hot fluid is piped through radiators which use ram air to cool the fluid
Pg 157
57
# Air cooled system
What are 2 advantages
1. Reduced weight
2. Less moving parts
## Footnote
Pg 158
58
# Air cooled system
What component is used to increase the external surface area
DEEP FINS
## Footnote
Pg 158
59
# Air cooled system
What is the purpose of *cylinder baffles*
CONTROL FLOW OF AIR
| Ensures each cylinder evenly cooled
## Footnote
Pg 158
60
# Air cooled system
What component is used to control the flow of air to ensure each cylinder is evenly cooled
CYLINDER BAFFLES
## Footnote
Pg 158
61
# Temperature measurement
Where does the highest temperature occur in an engine
CYLINDER HEAD
## Footnote
Pg 159
62
# Temperature measurement
What does CHT stand for
CYLINDER HEAD TEMPERATURE
## Footnote
Pg 159
63
# Temperature measurement
How is the *CHT* measured
THERMOCOUPLE
## Footnote
Pg 159
64
# Temperature measurement
What 4 things affect the temperature a *cylinder head* opeartes at during *normal operation*
| P A M S
## Footnote
More cylinders gives **P**ower **A**nd **M**ore **S**peed
1. **P**OWER
2. **A**IR
3. **M**IXTURE
4. **S**PEED
## Footnote
1. POWER - Amount of power being produced
2. AIR - Temperature of cooling air
3. MIXTURE - Mixture ratio
4. SPEED - Mass flow of cooling air - aircrafts forward speed
Pg 159
65
# Temperature measurement
What type of mixture will cause an *increase* in CHT
LEAN MIXTURE
(weak)
## Footnote
Less mixture means less cooling of the cylinder head
Weak mixture burns more slowly which gives more time to heat components
Pg 160
66
# Temperature measurement
What conditions are *most likely* to cause engine *overheat*
low speed, HIGH POWER
| Example: Extended climb
## Footnote
Low speed means less air flow entering the engine to assist with cooling
High power means the engine is working hard and hot
Pg 160
67
# Temperature measurement
What condictions are *most likely* to cause engine *over cooling*
HIGH SPEED, low power
| Example: High speed descent with idle power
## Footnote
High speed means excessive air is entering the engine to assist with cooling
Low power means the engine is hardly working and is cooling down in the process
Pg 160
68
# Temperature measurement
What is a risk of *over cooling* an engine
THERMAL SHOCK
## Footnote
Pg 160
69
# Temperature measurement
What are fitted on some engines to assist with regulating the flow of cooling air
COWL FLAPS
## Footnote
Pg 160
70
# Temperature measurement
*Cowl flaps* are OPENED or CLOSED for *full power climb*, and OPENED or CLOSED for *low power descent*
1. OPENED
2. CLOSED
## Footnote
Power on climb means engine is working hard and slow airflow, so more air is needd to assist in cooling
Low power and fast descent means more air may result in thermal shock. Less air is required to flow over the engine
Pg 160
