Aircraft Systems Part 2/2 Flashcards
Name parts of a spark engine ignition system
L & R magnetos, spark plugs, high tension leads, ignition switch
Name 5 positions of the ignition system
- Off
- R (right)
- L (left)
- Both
- Start
Where is the permissible RPM decrease from the Mag switch listed?
AFM or POH
If there is an excessive RPM drop or the engine stops running from switching to 1 magneto, what could be the cause?
- Fouled plugs
- Broken or shorted wires btw mags & plugs
- Improperly timed firing of plugs
No drop in RPM is
NOT normal. Airplane should not be flown.
Engine can still fire if
Ignition is left on even with battery and master switches off
Name functions of the engine oil system
- Lubrication
- Cooling by removing friction
- Removing heat from cylinders
- Providing a seal between the cylinder walls & pistons
- Carrying away contaminants
Reciprocating engines use either:
- Wet sump oil system (oil located in a sump and pumped)
2. Dry sump oil system (oil contained in a separate tank and is circulated via pumps)
Describe what the oil pressure gauge does.
It ensures the pressure in lbs/sq. inch (PSI) of the oil supply to the engine.
High oil temp could indicate:
- A plugged oil line
- Low oil quantity
- Blocked oil cooler
- Defective temp gauge
Low oil temp could indicate:
- Improper oil viscosity for cold weather
Where can you find the correct oil type, weight, and quantity for your airplane?
AFM - airplane flight manual
POH - pilot operating handbook
Air-cooling is less effective than liquid cooling when?
Low airspeed especially with high power (ground operations, take-offs, go arounds)
High speed descents provide excess air and can…
shock cool the engine subjecting it to abrupt temp fluctuations
Operating an engine at a temp higher than its designed for can cause:
- Loss of power
- Excessive oil consumption
- Detonation
- Damage such as scoring the cylinder walls, damaging the pistons and rings, burning and warping valves
To avoid excessive cylinder head temperatures:
- Increase airspeed
- Enrich mixture
- Reduce power
What is detonation?
An uncontrolled explosive ignition of the fuel/air mixture within the cylinder
What does detonation cause?
Excessive temp & pressure, engine overheating, roughness, loss of power
Detonation is characterized by what?
High cylinder head temps and is most likely to occur at high power settings
Operational causes of detonation include:
- Use of a lower fuel grade than recommended
- Operation at high MAP with low RPM
- Operation at high power with excessively lean mixture
- Extended ground operations or steep climbs, with reduced cylinder cooling
How can you prevent detonation?
- Use proper fuel grade
- Fully open cowl flaps for ground operations
- Use an enriched mixture and shallower angle for takeoff and initial climb
- Avoid extended high power, steep climbs
Preignition occurs when?
When the fuel/air mixture ignites prior to the normal ignition event
Pre-ignition is usually caused by:
Residual hot spot in combustion chamber often created by
- a carbon buildup on a spark plug
- a cracked spark plug insulator
- or other cylinder damage which allows sufficient heat to build to ignite the fuel/air mixture
What does preignition cause?
- loss of power and high operating temperature
- Severe engine damage, as it places pressure on piston while still in compression stroke
