2014 KCSE Aviation Technology Past Paper
3.22 AVIATION TECHNOLOGY (450)
3.22.1 Aviation Technology Paper 1 (450/1) 1 (a) (bl SECTION A (44 marks)
Answer all questions in this section.
Differentiate between class B and C types of fire. (2 marks) State the type of fire extinguishing agents used for each of the following classes of fire. (i) Class C (ii) Class D 2 Outline three roles of aircraft dispatchers. 3 Explain four measuring instmments used by meteorologists. 4 (a) (b) 5 (a) (b) (C) 6 (a) (b) State two advantages of using blind rivets. Explain the reason why structural screws are used for joining aircraft parts. Differentiate between profile drag and induced drag. Sketch airflow pattern over each of the following body shapes (i) Flat plate (ii) Stationary cylinder (m) Streamlined. Describe the behaviour of“Boundary layer” on an aircraft wing in flight. Differentiate between non-destructive and destructive testing. Define each of the following terms as applied in aircraft structures: (i) fuselage; (ii) cockpit. 7 Distinguish between a wet sump and dry sump aeropiston oil lubricating system. (2 marks) (3 marks) (4 marks) (2 marks) (1 mark) (2 marks) (3 marks) (2 marks) (2 marks) ( 6 marks) 8 (a) Outline the meaning of each of the four range colour markings on aircraft instruments. (4 marks) (b) Give two aircraft instruments controlled by gyroscopes. (1 mark) 9 (a) Explain how each of the following tools are used during fabrication of aircraft parts. (i) Bucking bars; (ii) Countersink bit. (2 marks) (b) State two reasons for removing paint on an aircraft part. (2 marks) 10 Sketch the following drawing symbols: (4 marks) (a) Machined surface (b) Long break line (c) Ohmmeter (d) Transformer SECTION B (56 marks) Answer any four questions from this section. 11 The figure below shows an isometric drawing of an aircraft hinge bracket. M “5 av i M K / “in m fl X“ X5 5:) K \*\ \*\N ALL FLANGES 10mm g‘ FOUR HOLES ¢ 15 A R15 Draw FULL SIZE in Third Angle projection the following views (Use A3 paper provided): front elevation in the direction of arrow A; (a) (b) end elevation in the direction of arrow B; (c) plan. 12 (3) (14 marks) Explain four operational differences between Aeropiston and Aerojet engines. (4 marks) (b) With the aid of a labelled sketch, show the cross-section of an aircraft propeller governor. (10 marks) 13 (a) (b) (Q) 14 (3) (b) 15 (a) (b) (C) Outline three advantages of plastics over metals in aircraft construction. (3 marks) Explain five selection criteria for aircraft engine bolts. (5 marks) Outline the procedure of making a through M10 threads on a 10mm mild steel plate. (6 marks) Explain four functions of aircraft tabs during flight. (4 marks) With the aid of labelled sketches, describe the operation of each of the following aircraft tabs to effect pitching moments. (i) Servo (ii) Trim (10 marks) Define each of the following terms as applied to Aviation industry. (2 marks) (i) Indicated airspeed. (ii) Ground speed. Explain the function of each of the following aircraft electrical safety devices. (3 marks) (i) Magnetic indicators. (ii) Circuit breakers. (m) Weight switch. With the aid of a labelled sketch, explain the principle of electrical power generation of an aircraft. (9 marks) 3.22.2 Aviation Technology Paper 2 (450/2) INSTRUCTIONS STATION 1 Fgure 1 shows the exploded view of light aircraft single disc brake assembly. On the drawing paper provided: (a) Sketch in good propoition a pictorial view of the assembled unit. (7 marks) (b) Name the six parts labelled 1,2, 3, 4, 5 and 6. (3 marks) 1 INSTRUCTIONS Using the tools, materials and e u STATION 2 q ipment provided, make an aircraft panel hinge shown in figure 2. (10 marks) STATION 3 INSTRUCTIONS Using the Bunsen burner, materials and tools provided carry out the following (a) (i) Hold the piece marked K on the Burner and observe as it burns and fill the table below. (ii) Repeat a(i) on the piece marked L. Application Observation Material (b) Using the materials and tools provided, carry out the following. (3 marks) Centre punch each of the materials marked M and N and fill the table below. Application Mark Observation Material l M i N (3 marks) (c) Identify each of the following aircraft breakdown spares labelled P and R and fill the table below. Requirement Spare Use Probable fault Maintenance (4 marks) SECTION 4 INSTRUCTIONS Study the aircraft component and do the following: (a) (i) Identify the component and state its function. (ii) Remove the circlip. Let the examiner check your work. (m) Name the parts painted Red, Blue and Yellow and state the function of each. Name Function Red …………………………………………………………………….. .. Blue ……………………………………………………………………… .. Yellow …………………………………………………………………………………………….. .. (iv) Observe two defects on the parts and state the effect of each. Defect Effect (v) Assemble the component. Let the examiner check your work. (b) (i) Explain how the component is operated. (ii) Give the major maintenance task on the component. (8 marks) (2 marks) STATION 5 INSTRUCTIONS Study the components labelled A, B and C and carry out the following (a) (i) Identify the components (ii) State the type (m) State the condition (iv) State the use. Component Identification Type Condition Use (6 marks) (b) Study the aircraft fuel system components labelled D and E and do the following: (i) Identify the pans. D …………………………………………………………………………… .. E …………………………………………………………………………… .. (ii) State where each is used. D …………………………………………………………………………… .. E …………………………………………………………………………… .. (m) State two maintenance requirements. (iv) State two rejection criteria. (4 marks) STATION 6 INSTRUCTIONS Study the aircraft tyre provided and do the following (a) Identify the tyre defects labelled A to E, state the cause of each on an aircraft and complete the table below. ITEM DEFECT PROBABLE CAUSE A B C D E (b) State the importance of the parts marked White and Blue. White …………………………………………………………………………… .. Blue …………………………………………………………………………… .. (c) Give three manufacturer’s specifications on the tyre and the meaning of each. l ………………………………………………………………………………………. .. 2 ………………………………………………………………………………………. .. 3 ………………………………………………………………………………………. ¢4 (5 marks) (2 marks) (3 marks) STATION 7 INSTRUCTIONS Study the markings on aircraft model labelled X and Y provided, representing imaginary arrangement of lines of forces according to aircraft design and do the following: (a) determine the correct arrangement of the lines of forces; (1 mark) (b) identify each of the lines on the correct arrangement and give reasons; l ………………………………………………………………………………………………………………. .. 2 ………………………………………………………………………………………………………………. .. 3 ………………………………………………………………………………………………………………. .. 4 (4 marks) (c) name points 5, 6 and 7 and state reason for the position of each; 5 ………………………………………………………………………………………………………………. .. 6 ………………………………………………………………………………………………………………. .. 7 ………………………………………………………………………………………………………………. .. (3 marks) (d) give two advantages of the correct arrangement; STATION 8 INSTRUCTIONS The pilot for aircraft marked “A” has been cleared to taxi and encounters each of the scenarios 1“, 2N”, 3RD, 4″‘ and ST“ as shown on the airfield plan provided. Study each scenario and in the table below state the expected immediate action and reason for the action. (10 marks) SCENARIOS IMMEDIATE REASON FOR THE ACTION ACTION 1ST 2ND 3RD 4TH 5TH STATION 9 INSTRUCTIONS (a) Connect the components as shown in figure 3. Let examiner check your work. (5 marks) / S1 E /‘.52 Fig.3 ® (b) (i) Close switch S] and S2 and state what happens. :_-3 12 volts T (ii) Select switch S2 to off position and state what happens. (m) State the reasons behind your observations in b(i) and b(ii). Reasons for observation in b(i) ……………………………………………………. .. Reasons for observation in b(ii) …………………………………………………… .. (c) State one application of each of the circuit modes in a(i) and a(ii). STATION 10 INSTRUCTIONS Study the four stroke engine component provided and do the following: (a) (i) identify the component. (ii) state the material used for its manufacture. (m) name type of gear. (iv) record the number of teeth. (4 marks) (l mark) (2 marks) 219 §’ (b) Measure and record each of the following: (i) diameter of the journal labelled A. (ii) height of the lobe labelled B. (m) distance between lobes B and C. (iv) the angle of the lobe labelled B. (c) Give the functions of: (i) component (ii) areas painted Blue …………………………………………………….. .. Red …………………………………………………….. .. Yellow (d) Name two maintenance aspects and two possible faults: (i) Maintenance aspects. (ii) Possible faults. 4 marks) (2 marks) (2 marks)
2014 KCSE Aviation Technology Past Paper-Marking Scheme/Answers
4.22 AVIATION TECHNOLOGY (450) 4.22.1 Aviation Technology Paper 1 (450/1) 1. (a) Types of aircraft fires (i) Class B fire involves inflammable fluids such as gasoline, kerosine oils etc. while (ii) Class C fire involves energized electrical equipment. (2 marks) (b) Types of fire extinguishing agents (i) Class C – carbon dioxide. (ii) Class D – dry powder. (2 marks) 2. (a) Roles of aircraft dispatchers: (i) Schedule flights. (ii) Ensure all civil aviation regulations are adhered to. (m) Flight plans. (iv) Supply meteorological reports. (v) Briefing the flight crew. (Any 3 x 1 = 3 marks) 3. Meteorological measuring instruments. (i) Hydrometer – for measuring humidity. (ii) Barometer – for measuring air pressure. (m) Windvane/Anemometer – for measuring speed and direction of wind. (iv) Thermometer – for measuring temperature. (v) Rain gauge – for measuring the amount of rain. (Any 4 x 1 = 4 marks) 4. (a) Advantages of blind rivets. (i) Long grip area/length. (ii) Easy to use. (m) Easily accessible from one side. (iv) Less noisy. (Any 2 x 1 = 2 marks) (b) Reasons for using structural screw. Made of alloy steel, properly heat treated, definite grip length, shear and tensile strength. (1 mark) . Types of drag. Profile drag is the resistance encountered by virtual of forcing an abject viscous fluid tending to stick to the object owing to its shape, while induced drag is the resistance formed on the wing tips owing to vortices of bottom and top air flow. (2 marks) (b) Body shapes airflow patterns. (i) Flat plate (ii) Stationary cylinder(3 x 1 = 3 marks) (c) Behaviour of “Boundary Layer” Boundary layer is a thin layer of air lying over the surface of the wing from zero to full velocity. Because air has viscosity this layer of air tends to adhere/ stick to the wing. As the wing moves forward through the air; the boundary layer as first flows smoothly (lamina) over the stream line shape. As the boundary layer approaches the centre of the wing it begins to break away from the surface forming eddies to become turbulent at separation point. The layer in actual contact with the surface moves at zero velocity relative to the wing. (It moves at the same speed as the wing). 6. (a) Testing methods. Non destructive testing is an adequate means of checking the serviceability of an aircraft part without causing any harm. while Destnictive testing is a means of checking a specimen of an aircraft part on the assumption that the aircraft will behave in the same manner. The specimen is destroyed. (2 marks) (b) Aircraft stmcture terms. Fuselage – the main body of the aircraft which accommodates passengers, crew and cargo and the main attachment of other parts of the aircraft. while Cockpit is a compartment forming a part of the fuselage to accommodate the flight crew. (2 marks) Types of aeropiston oil systems. “Wet sump” – Oil is stored beneath the crankshaft in the oil pan. – Oil pump sucks oil from the bottom pan through a tube and the pumps to the rest of the engine. – The pan has to be large enough to accommodate sufficient oil. while “Dry sump” – Extra oil is stored in a tank outside the engine rather than the oil pan. – As at least a suction and a seavage pump. – The maximum amount of oil remains in the engine. (6 x 1 = 6 marks) 8. (a) Aircraft instniment range colour markings. (i) Red radical line – indicates maximum and minimum operating ranges. (ii) Blue arc – indicates that operation is permitted under certain conditions. (m) Green arc – indicates the normal operating range. (iv) Yellow arc – indicates caution operating range. (v) White arc – indicates the alignment of the glass and instruments (An: (b) Gyroscopic instruments: (i) Artificial horizon. (ii) Heading indicator. (m) Tum and slip indicator/turn and back indicator. (Any 2 X % = 1 mark) 9. (a) Fabrication tools. (i) Bucking bar – a tool held against the shank end of a rivet While the snap head is being formed. (ii) Countersunk bit – a tool which cuts a cone shaped depression around a rivet hole to allow the rivet to set flush with the surface of the skin. (2 X 1 = 2 marks) (b) Reasons for paint removal on aircraft parts. (i) Deterioration of the paint. (ii) When corrosion is evident. (m) Inspection purpose. (iv) Retention of original paint. (v) To retain the original Weight of aircraft. (Any 2 X 1 = 2 marks) 10. Drawing symbols. (i) Machined surface i \ \\ (ii) Long break line ’\< N (m) Ohmmeter (iv) Transformer (4 X 1 =4 marks) 11. FULL SCALE 3×1 POSITIONING 3×1 FACES 9×72 HIDDEN DETAILS exa- NEATNESS : 3mk5 =43: mks = 3mkS =/’§mk TOTA L T =14mks NOTE ALL HOLES 615 ‘ALL FLANGES 10 12. (a) (i) (ii) (m) (iv) (V) (vi) (b) Engine operational differences. Aeropiston engine uses gasoline as the fuel media While aerojet engine uses kerosine as fuel. In Aeropiston engine all the cycles occur in the same cylinder while in Aerojet engine cycles occur in different chambers. Ignition occur on every cycle on aeropiston engine While it only occurs during starting on aerojet engine. Aeropiston engine generates thrust With a propeller while aerojet engines generates thrust with jet efflux. Aeropiston engine operates at peak temperatures while the aerojet operates at constant temperatures. Aeropiston engine uses mineral oil While aerojet engine uses synthetic oil for lubrication. (Any 4 x 1 = 4 marks) Centrifugal forces inlet ‘_> ENGINE DRIVEN PUMP Fly weights Return spring Pilof valve CYLINDER Z MASTER SKETCH = Smurks mum *= TOTAL = 10 mur 13. (a) 14. (a) (i) (ii) (m) (iv) (v) (vi) “9? (vm) Advantages of plastics over metals. High strength to Weight ratio. Does not reflect sound and rays. Poor conductors of heat thus can be used as an insulators. Resistant to corrosion. Can be coloured for good interior decoration. Easily machined. Cheaper. Transparent. (Any 3 X 1 = 3 marks) (b) Selection criteria for aircraft engine bolts. (i) (ii) (m) (iv) (v) (vi) Length – this depends on the Width of the pieces to be joined. Thread – the type of thread may be metric or British, coarse or fine. Material – depends on the material being joined to avoid reaction. Type of head – Whether hexagonal, allen head or clevis head. Heat treatment – Whether coated, hardened or annealed. Method of locking – seal, castrated, locking Wire, split pin. (Any 5 X 1 = 5 marks) (c) Making a M10 through thread on l0 mm mild steel. (i) (ii) (m) (iv) (v) (vi) (vi) (i) (ii) (m) (iv) (v) Mark out and centre punch the location of the hole. Drill with an appropriate drill bit. Holding the taper tap at right angles to the plate cut the threads clock Wise for half a revolution and anti-clockwise for quarter of a revolution through the plate using appropriate lubrication. Repeat step (m) using intermediate tap. Repeat step (iv) using plug tap. Debur and clean off the swarf. Test With M10 bolt for tolerance. (Any 6 X 1 = 6 marks) Function of aircraft tabs. Trimming purpose. Augment the force required by the pilot. Increase the effort required by the pilot. Fine correction of the selected primary controls position. To relief the pilot on repeatative manoeuvre. (4 X 1 = 4 marks) (b) Types of tabs. (i) Servotab Control . Stick Tail plane Elevator /Servo tab _-L Q ’ fiitiontrol cable This is the type of tab that is connected to the main control stick to raise or lower the aircraft nose. When it is required say to lower the nose the control stick is pushed forward. Pushing the control stick raises the servo tabs. Raising the servo tab increases the bottom camber of the elevator to lower the elevator. Lowering the elevator increases the top camber of the tail plance to generate lift and raise the empennage to rotate the aircraft about the lateral axis and lower the nose of the aircraft and vice versa. Sketch l mark Labelling 2 marks Explanation 2 marks 5 marks (ii) Trim tab Control Stick Tail plane ‘ Elevator ,_Trimrning fab _ 0 Control rod Trim Trimming rod wheel When required say to raise the nose of the aircraft the control stick is pulled backwards. Pulling the control stick lowers the trim tab. Lowering the trim tab increases the top camber of the elevator to generate lift that raises the elevator. Raising the elevator increases the bottom camber of the tail plane to generate lift at the bottom to pull the empennage downwards to rotate the aircraft about the lateral axis to raise the nose of the aircraft. Sketch l mark Labelling 2 marks Explanation 2 marks 5 marks (Total 14 marks) 15. (a) Aircraft terms. (i) Indicated airspeed – This is the rate at which the air particles move past an aerofoil of the aircraft wing in flight. (ii) Ground speed is the velocity with which the aeroplane moves over the earths surface. (2 marks) (b) Aircraft electrical devices. (i) Magnetic indicators – these are devices acting as feed back to practically confirm that the selected value has actually opened or closed on selection. (ii) Circuit breaker – these are devices used to isolate faulted circuits but can be manually reset when faults clears. They can also be tripped to simulate a condition on an aircraft system. (m) Weight switch – this is a device that moves on ground to prevent some systems not to be operated when the aircraft is on ground. (3 marks) (c) Electrical power generation. Magnetic flux current Commutulor K ’ k D.0.R x I 1 Horse shoe Magnet Consfanf speed drive SKETCH = 2 marks Engine LABELS, Any8x7¢= 4 marks EXPLANATION : 3 marks 5% TOTAL: 9mc|rk5 The aircraft engine rotates through a constant speed and drives a coil placed in a strong magnetic field. Cutting magnetic lines of forces creates a magnetic electromotive force (EMF) that induces a potential difference to cause a current to flow. This current can be picked by commutators or brushes to be supplied to the aircraft. (9 marks)
