Progress Test Flashcards
What is the problem with pressurising aircraft?
Each CYCLE of pressurisation causes STRETCHING of the FUSELAGE placing the structure under TENSION stress and the FASTENERS under SHEAR stress, followed by the DEPRESSURISATION returning the aircraft structure to normal
As an aircraft ages, why is its cabin pressure and operating heights reduced?
To alleviate TENSION stress levels
What are the other factors that lead to the degrading of aircraft fatigue life?
Manoeuvres OUTSIDE the aircrafts OPERATING ENVELOPE;
Flight through TURBULENT WEATHER;
HEAVY LANDINGS
What are the 4 types of gas turbine fuels?
TURBO FUEL A (AVTUR 40);
TURBO FUEL A-1 (AVTUR 50);
TURBO FUEL B (AVTAG or WIDE CUT);
TURBO FUEL 5
How are the gas turbine fuels A, A-1, and B identified?
A: Colourless or straw, 1 BLACK STRIPE on piping;
A-1: Colourless or straw, 2 GREY STRIPES on piping;
B: Colourless or straw, 3 YELLOW STRIPES on piping
How can it be determined what type of fuel an aircraft requires?
Stated in the FLIGHT MANUAL;
Stated and/or displayed as NATO SYMBOL on the LABEL near the FILLER CAP;
Stated in the TECH LOG;
Stated in the FUEL SHEET
What are the main characteristics of turbo fuel A?
Called “JET-A” or “CIVIL AVIATION KEROSENE”;
Essentially contains NO GASOLINE BLEND and is the PRIMARY fuel for COMMERCIAL and GENERAL AVIATION;
Generally NO MILITARY use
What are the main characteristics of turbo fuel A-1?
Called “JET A-1”;
LOW TEMPERATURE fuel with LOWER FREEZING POINT than JET A;
Used by most INTERNATIONAL AIRLINES
What are the characteristics of turbo fuel B?
Called “JET B”;
Blend of 30% KEROSENE and 70% GASOLINE, known as a WIDE CUT FUEL;
VERY LOW FREEZING POINT and LOW FLASH POINT;
Primarily used in MILITARY and SIMILAR to fuel JP-4
What are the characteristics of turbo fuel 5?
Called “JP-5”;
HIGH FLASH POINT military fuel;
Used primarily aboard NAVAL AIRCRAFT CARRIERS
What are the properties that gas turbine fuels should have?
Be PUMPABLE and FLOW EASILY under ALL operating CONDITIONS;
Permit ENGINE STARTING at ALL GROUND CONDITIONS and give SATISFACTORY flight RELIGHTING characteristics;
Give EFFICIENT COMBUSTION at ALL CONDITIONS;
Have as HIGH a CALORIFIC VALUE as possible;
Produce MINIMAL HARMFUL effects on COMBUSTION SYSTEM or TURBINE BLADES;
Produce MINIMAL CORROSIVE effects in the FUEL SYSTEM COMPONENTS;
Provide ADEQUATE LUBRICATION for the MOVING parts of the FUEL SYSTEM;
Reduce FIRE HAZARDS to a MINIMUM
What is the calorific value?
Why is it important?
An expression of the HEAT or ENERGY content PER POUND or GALLON that is RELEASED during COMBUSTION;
It INFLUENCES the RANGE of an aircraft
When the limiting factor of an aircraft is fuel capacity what should the calorific value be? Why?
The CALORIFIC VALUE PER UNIT VOLUME should be as HIGH as possible;
This means there is MORE ENERGY and therefore MORE RANGE, to be OBTAINED from a MINIMUM VOLUME of fuel
When the limiting factor of an aircraft is useful payload what should the calorific value be? Why?
The CALORIFIC VALUE PER UNIT WEIGHT should be as HIGH as possible;
This means there is MORE ENERGY and therefore MORE RANGE, to be OBTAINED from a MINIMUM WEIGHT of fuel
What other factors must be considered when choosing a calorific value in terms of volume or weight?
TYPE of aircraft;
DURATION of flight;
Required BALANCE between FUEL WEIGHT and PAYLOAD
Why do turbine fuels tend to corrode the components of the fuel and combustion systems?
Turbine fuels contain both SULPHUR and WATER contents;
When SULPHUR is BURNT in AIR it forms SULPHUR DIOXIDE;
When SULPHUR DIOXIDE is MIXED with WATER it forms SULPHUROUS ACID;
SULPHUROUS ACID is very CORROSIVE especially towards COPPER and LEAD
How is corrosion of the components of the fuel and combustion system minimised?
Why can it not be fully eliminated?
It is IMPRACTICABLE to completely REMOVE SULPHUR so it is REDUCED to a MINIMUM;
FREE WATER is REMOVED prior to use however DISSOLVED WATER CANNOT be effectively REMOVED as the fuel would REABSORB MOISTURE when stored in a VENTED storage TANK
What are the 3 types of fuel tanks used in large transport aircraft?
RIGID;
BLADDER;
INTEGRAL
What are the characteristics of rigid type tanks?
Requires an OPEN SPACE in the STRUCTURE for installation;
Usually made of ALUMINIUM ALLOY with WELDED JOINTS;
Sometimes can be COVERED with a SHOCK RESISTANCE RUBBER COATING which often has SELF SEALING capabilities
What are the characteristics of integral/wet wing tanks?
STRUCTURE is SEALED during construction enabling the COMPLETE STRUCTURE to BECOME the FUEL CELL;
Makes BEST USE of EMPTY SPACE within structure
What are the characteristics of bladder type tanks?
Made of THIN FABRIC, IMPREGNATED with NEOPRENE or some similar material that is IMPERVIOUS to FUEL;
May be SELF SEALING
What additional components are most tanks fitted with? Why?
BAFFLES;
INCREASE STRENGTH and REDUCE fuel SURGING during ALTITUDE CHANGES
Why may tanks be pressurised?
REDUCE VAPORISATION;
Provide a POSITIVE HEAD of FUEL to the SYSTEM PUMPS;
Do gravity fed tanks require an additional feature? Why?
VENTING system;
To ensure the tanks DO NOT suffer from CAVITATION