Air Tech Flashcards
What does Ramp Weight include / exclude?
Zero fuel weight
Fuel
Can be more than Take-off Weight if fuel burnt for taxiing occurs.
What does Gross Weight include/exclude?
Basic Empty Weight
Pilot + Crew + Baggage
Payload
Fuel
What does MCTOW stand for?
Maximum certificated takeoff weight
What’s does MCLW stand for?
Maximum certificated landing weight
Explain when you would use ram air, filtered air & carburettor heated air?
Ram air - for maximum performance & volumetric efficiency.
Filtered air - whilst near ground or when air needs filtering.
Heated air - when icing is affecting performance.
List advantages and disadvantages of a generator.
Disadvantages
- Heavier & larger than alternators
- Produce less current per rpm
What is compass deviation?
The angle between the magnetic meridian & the compass needle.
What would indicate a failure in the Pitot Static system?
The ASI will indicate a false reading.
Under what conditions would you be susceptible to carbon monoxide poisoning?
- Hovering in a tail wind
- Leaking exhaust manifold
- Taxiing downwind
What is detonation?
Spontaneous combustion of fuel-air mix after normal ignition.
Arises from mixture charge being too high pressure &/or temperature.
Describe the function of the inlet valve & the exhaust valve.
Inlet to allow fuel-air mix into the cylinders.
Exhaust valve to provide an outlet for burnt exhaust gases.
What is pre-ignition?
Combustion for fuel-air mix before normal combustion.
Arises from hot spots/carbon deposit igniting - hit & dirty engine.
Explain methods of reducing Cylinder Head Temp in a piston engine helicopter.
- Keep fuel mix on the richer side.
- Don’t do long descents with the throttle closed.
- Don’t climb at high power & low speed.
Define amps
Rate of current flow.
Define volts
Electrical pressure
Define ohms
Electrical resistance
State ohms law
A pressure of 1 volt applied a current of 1 amo will flow through a conductor which has a resistance of 1 ohm
Explain the difference between direct current and alternating current.
Direct current is a continuous flow of electrical current around a circuit.
Alternating current is when the current regularly changes flow from one way around the circuit than the other
What are the benefits of valve lead?
Reduces back pressure on the piston during the early part of the exhaust stroke.
Allows more time for the exhaust games to exit the cylinder.
What is the function of a voltage regulator?
To maintain a desired voltage output to the battery & electrical services.
If the engine oil temp & cylinder head temp gauges have exceeded their normal operating range you may have been doing what?
Operating with too much power & with the fuel mixture set too lean.
What is the purpose of a venturi in a float type carburettor?
To create a pressure drop, which will draw fuel into the airstream.
Will the alternator of a helicopter supply electrical current to a helicopters electrical system if the aircraft’s battery is flat?
No
Magneto system has a faulty ground connection. What will this cause?
Engine will keep running however magnetos will still be “hot” when key is off.
What are some of the consequences of operating an engine for extended periods with an overly rich mixture?
- Lower than optimal CHT
- Fouling of spark plugs
- Loss of power
- Rough running
If a centre zero ammeter continues to show charge for an extended period after start up. What is going on?
There is a possibility that the battery is being overcharged & and the flight should be terminated.
(Voltage regulator failure)
How is the mixture controlled in a fuel injection system?
With the throttle butterfly & metering unit
Of the engine air take filter became partially clogged, how would max manifold pressure & max hovering ceiling be affected?
Manifold pressure would be decreased.
Max hover ceiling decreased.
What is the purpose of a pressure relief valve in the oil system?
Relives pressure when it reaches a predetermined limit.
When full carburettor heat is applied to melt ice, which has formed in the carburettor, the engine may initially run very rough because?
The density of the air entering the engine has decreased, further upsetting the mixture ratio.
Pilot notices altimeter has stopped changing with climbs & descents & the VSI needle is frozen at 0. If the pilot climbs to a higher altitude, they should expect the ASI to what?
Progressively under-read
Flight with a door removed results in a cabin pressure lower than ambient pressure. If the static pressure line develops a leak inside the cabin how would the altimeter & ASI be affected?
Altimeter - Read high
ASI - Read high
What is the function of the idle jet in a carburettor?
To provide extra fuel at low RPM when the main fuel jet becomes unreliable.
What actions should you take if a fuse or circuit breaker pops?
Both fuses & circuit breakers should only be replaced or reset once.
What does a magnetometer do?
Sense the direction of the earth’s magnetic field
List one of the more important functions of the alternator?
To recharge the battery
A typical fuel quantity detector system is what?
Is calibrated for straight & level flight.
Electric detector may have float or capacitor.
Float detector located in tanks is accurate in most attitudes.
GPS RAIM warning appears.
What does it mean?
Insufficient satellites are available or accuracy degraded.
In cruise flight, the symptoms of carburettor icing in helicopters are what?
- Loss of power
- Reduction of boost
- Lower RPM
- Potential rough running
Impending engine failure is most likely to be indicated by the combination of what?
Fluctuating or low oil pressure
&
High oil temp
Given a constant IAS describe the relationship between TAS & air pressure / air density.
TAS increases with a decrease in air density.
A basic fuel injection system is….?
- Indirect injection.
- Injection in manifold just prior to intake valve.
List advantages of solid state ignition.
- Better fuel economy
- Easier starting
- Less maintenance
Define Rated Altitude.
Altitude where rated power is developed at full throttle.
Most piston engines will be somewhere near sea level.
Define Torque
Force which produces a twisting or turning force.
Define Brake Power
Engine power measured from the crankshaft.
Define rated power
Power that is stated in the Pilot’s Operating Handbook
Brake power developed by an engine in good condition at ISA
Define full throttle height
Altitude where a given manifold pressure cannot be maintained & begins to reduce.
Define volumetric efficiency
Relates to the ability of the engine to breathe.
Define mechanical efficiency
Relationship between brake power produced & the indicated or theoretical power that could be created.
Define thermal efficiency
Potential energy stored compared to the useful work created
What does payload include/exclude?
Anything that is paying to be on the flight.
Passengers
Their baggage
Freight or cargo
What system is designed to help avoid collisions with terrain?
TAWS - Terrain awareness & warning system.
Provides aural & visual warning.
What is a unit type fire detection system?
Usually thermocouples or bi-metallic switch.
Usually situated at points where an outbreak of a fire is most likely to occur.
What is the purpose of the main rotor transmission?
To reduce engine RPM to the ideal rotor RPM.
For practical purposes, current flows in what direction?
Positive to negative
(Which is the opposite to actual electron flow)
What occurs inside a lead acid battery?
Chemical reaction in the electrolyte causing electrons to flow between dissimilar metals.
A hydraulic system operating at 2000psi acts on a jack with a piston area of 2 inches. How much force is being applied to that jack?
4000Ilbs
(2000psi x 2inches = 4000Ilbs
What does an enrichment system on a carb system do?
Provide extra fuel for cooling at high power settings
Static leak inside an unpressurised aircraft, what will the altimeter read?
Over-read
What is the purpose of fuel tank baffles?
Increase strength & prevent surging during flight maneuvers & turbulence.
What’s an advantage of a hydraulic system?
Small input force transferred to a large force somewhere else.
Describe the errors associated with a Vertical Speed Indicator
Lag error
> Due to how it works there is always lag.
Position error
> Fluctuations in pressure at the static vent may cause fluctuations in the VSI even at level flight.
Describe errors associated with an altimeter.
Instrument error
> Caused by small imperfections from manufacture & installation
Position error
> Caused by problems with the position of static vents
Instrument lag
> Altimeter takes time to adjust to rapid changes
List disadvantages of fuel injection systems
- Vapour lock
- Susceptible to fuel contamination
- Greater need for an awareness of fuel distribution
List advantages of fuel injection systems?
- No refrigeration ice
- Uniform delivery of fuel-air mix
- Fewer maintenance problems
- Better throttle response
- Increased engine efficiency
