Aircraft Systems 1 Flashcards
What is Dilution Air when referring to gas turbines?
Dilution Air is airflow injected through holes in the liner at the end of the combustion chamber to help cool air before it reaches the turbine stages. The air is used to produce the uniform temperature profile desired in the combustor.

What are the effects of icing on an aircraft?
Thrust will decrease.
Lift will decrease.
Drag and weight will increase.
What is a torque meter?
The torque meter comprises two concentric shafts. The inner shaft is connected to engine drive and the reduction gearbox. The outer shaft is connected to the engine drive only. It measures the twist applied to the shaft.
What are the key properties of AVGAS that influence engine design?
AVGAS
- Anti-knock value - the resistance a fuel has to detonation. A good value is one that combusts smoothly throughout the combustion chamber.
- Volatility
- Vapour locking tendency
- Stability
- Solvent and Corrosion properties
Describe the compression stroke of the Otto cycle.
Compression
This stroke begins at B.D.C, or just at the end of the suction stroke, and ends at T.D.C.
In this stroke the piston compresses the air-fuel mixture in preparation for ignition during the power stroke. Both the intake and exhaust valves are closed during this stage.

What is the most suitable fuel for gas turbines?
AVTUR
What accessory systems can be drive by the gearbox?
Fuel control unit
High pressure fuel pump
Low pressure fuel boost pump
Oil Pumps
Scavenge pumps
Centrifugal breather
N1 Tachogenerator
DC Starter/Generator
Air Conditioning compressor
What is the purpose the jet pumps?
The jet pumps feed fuel from storage tanks to collector tanks. There are no moving parts, instead the jet pumps work using the ‘venturi’ principle.
Describe the function of a differential static pressure ice detector.
Differential static pressure ice detector.
The detector monitors the pressure differential between a series of holes on the leading and trailing edges. If holes become blocked, a pressure differential between the edges is created and an alarm is triggered.
What is Strain?
Strain is deformation caused by stress.
What is the optimum speed for turboprop operation?
Speeds up to 350kts, beyong which the efficiency of the propeller deteriorates rapidly because of shockwaves at the blade tips.
What is the purpose of stringers in a wing structure?
Wing Stringers allow the wing to react to bending movements and stiffen the wing skin,

What is thermal stress?
Rapid changes in temperature causes uneven expansion and contraction in a turbine blade which increases the stress in the blade. Minimising power changes and allowing temperature to stabilise before shutdown can reduce thermal stress and prolong blade life.
What parts of an aircraft require hot air for de-icing?
Inlet guide vanes
First stage of compressor blades
Nose cone
Nose cowling
During aircraft aerobatics what aircraft systems can prevent surging?
Hinge flip flop tube (flexible tube with weight)
Double entry LP fuel pump
Recuperator system
Describe the function of thermal (hot air) airframe anti icing?
Thermal airframe anti icing utilises hot air bled from the engine compressors. The hot air is fed through a system of valves, pressure regulators and mixing valves and then ducted to relevant areas.
Describe the function of a visual ice detector.
Visual ice detector
The unit is mounted outside the cockpit window in a location where ice build up can be observed. The probe is painted matt black and has a heater element if required.

What is the purpose of the fuel collector tanks?
The fuel collector tanks ensure the engine can be provided with an uninterrupted supply of fuel during turbulence and any aircraft attitude.
How does a centrifugal compressor work?
They accelerate the air mass by spinning the air. The amount of acceleration is dependent on the rotational speed of the compressor.
There is a stationary diffuser at the outer edge of the impellor and this converts kinetic energy to potential energy. The resultant airflow is now tangential to the flow at the intake.
What properties must AVTUR possess?
Ease of flow under all operating conditions.
Quick starting of the engine.
Complete combustion under all conditions.
A high calorific value.
Non-corrosive
Minimal fire hazard
Provide lubrication of the moving parts of the fuel system.
What is the difference between a scavenge and a pressure pump?
A scavenge pump has greater capacity thatn pressure pump to ensure complete scavenging of the bearings. They have to pump increased volume due to air leakage into bearing housing.
What is the purpose of frames in a fuselage structure?
The frames maintain the shape of the fuselage cross-section and improve the stability of the stringers.
What is the purpose of monitoring instruments in an oil system?
Monitoring Instruments
Sensors and switches feed cockpit display and central warning system (CWS) captions for engine monitoring.
What is the purpose of the oil tank?
Contains the lubricant.
May have sight glass or dipstick for measuring oil quantity.







































