School of Engineering

E230: AIRCRAFT SYSTEMS

UNDERSTANDING TEST 3

4. September 2013 Duration : 90 minutes

Name: ________________________________ Class: ________________________________ ID: ________________________________

Instructions To Students

1. This question paper consists of 12 printed pages, including this cover page and a supplemental one-page work sheet.

2. This is a closed book test. Mobile phones and other electronic communication devices are not allowed.

3. There are 10 MCQ questions and 6 short-answer questions in this test. Answer all the questions.

4. Answers to the MCQ questions must be written in the given MCQ answer sheet.

5. Begin and end the test when commanded by the invigilator.

6. Write all your answer in the space provided.

7. Use drawings and illustrations and your discretion to elaborate your answers.

Question Marks Out of

1. 10

2. 21

3. 8

4. 9

5. 18

6. 14

7. 20

Total

100

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Section A: Multiple Choice Questions (10 marks) Enter the correct answer in the bracket. Only one answer is correct per ques-tion (each question carries 1 mark). 1.1 Figure 1 shows the Garmin

G600 PFD. The term PFD stands for:

a) Personal Flight Display b) Peripheral Flight Data c) Primary Flight Display d) Performance and Flight

Data display

( C )

Figure 1: Garmin G600 PFD

1.2 In figure 1, the attitude indicator shows a pitch attitude of approximately:

a) 7o nose up b) 3o nose up c) neutral d) 5o nose down

( B )

1.3 In figure 1, the altimeter reads approximately:

a) 12 000 m b) 7 450 ft c) 3 001 m d) 800 ft

( B )

1.4 The electrical systems of an aircraft often use IDG. The term IDG stands for:

a) Internal Data Generation b) Inverted Direction Group c) Instant DC Generation d) Integrated Drive Generator

( D )

Y

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1.5 What are the typical alternating current (AC) parameters in conventional aircraft (such as the Airbus A320)?

a) 240 V, 50 Hz b) 115 V, 60 Hz c) 115 V, 400 Hz d) 400 V, 115 Hz

( C )

1.6 An Ice Detector on an aircraft can be designed as a vibration probe. Such a

probe would:

a) decrease its vibration frequency when ice is formed b) increase its vibration frequency when ice is formed c) stop vibrating when ice is formed

( A )

1.7 Leading edge slats and trailing edge flaps are used as lift augmentation devices

during slow flight. Split flaps increase lift by:

a) increasing the surface of the wing b) increasing the camber of the wing c) increasing both the surface and the camber of the wing

( B )

1.8 Which component of a pressurization system prevents the cabin altitude from

becoming higher than the flight altitude (i.e. the cabin pressure lower than the ambient pressure?

a) cabin rate of climb controller b) outflow valve c) negative pressure relief valve d) ground relief valve

( C )

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1.9 When swinging a magnetic compass, the compensation is made to correct for:

a) the magnetic dip b) the magnetic variation c) the magnetic deviation d) the compass oscillation

( C )

1.10 When cruising at 36 000 feet altitude the altimeter is typically set to standard or

1013.25 hPa. This altimeter setting is called:

a) QNH b) QNE c) QFF d) QFE

( B )

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Section 2 Short Answer Questions (90 marks) 2. A Learjet 35A, registration N110UN, undergoes pre-flight inspection after a night

stop in Aspen, Colorado. Night temperatures have been below freezing level and there was some snowfall as well.

Figure 2 Aspen airport in winter a) On initial inspection the air-crafts wings appear to be covered in snow with the thickness of about 10 to 15 mm. Can aircraft wing de-icing system remove that deposit of snow? No, cannot

(2 Marks) b) Give an explanation for your answer to question 2.a. The wing de-icing system is only effective for the leading edge of the wing (thermal de-icing or pneumatic boots). The upper and lower surfaces, control surfaces and lift augmenting devices are not de-iced.

Figure 3 aircraft wing on ground Ground de-icing is required.

(3 Marks)

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c) List three effects of icing on aircraft wings.

disturb laminar airflow over the wing

destroy lift

increase drag

increase weight

increase stall speed

decrease control surface efficiency

(6 Marks) d) Figure 4 shows two different wing de-icing systems. Compare the polished, metallic leading edge of the Learjet 35A wing (Figure 4 left) with the black, rub-bery of the Citation Bravo (Figure 4 right). Complete table 1 below to compare the two systems.

Figure 4 Leading edge Learjet wing (left) and Citation Bravo (right)

Item Learjet 35A Cessna Citation

type of wing de-icing device

Thermal System (i.e. hot wing)

pneumatic de-icing boots

source of energy for the operation of the device

engine bleed air (electrical system)

(engine) pneumatic sys-tem

advantage no mechanical motion low maintenance

simple design low energy consumption no ducting of hot gasses

disadvantage depletes engine power (in certain circumstances can-not be used when max thrust is required)

high maintenance cost ageing of boots

Table 1 (10 Marks)

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3. The static port is an important source of air data for numerous instruments. a) List three flight instruments which rely on static pressure as their data source. Altimeter (Altitude Indicator 1) ___________________________________ Vertical Speed Indicator (VSI) ____________________________________ Airspeed Indicator _____________________________________________

(6 Marks)

b) If a static port is blocked, several instruments lose their source of information. Describe one method which prevents an aircraft from such incident. dual static system, where there are two or more separate static systems and their instruments, or alternate static port, where there is a permanently connected or switchable secondary static pressure source in the same system, or use of a pneumatic instrument to supply alternate static pressure from the cabin only for non-pressurized flight

(2 Marks)

4. A flight crew reads on the master warning panel the illuminated pitot heat fail warning. To prepare for the possible consequences, describe in table 2 what would happen if the pitot tube would be blocked through ice build-up. Remark: While describing an inflight situation, consider various phases of flight.

Flight Condition Airspeed Indication with blocked pitot tube

straight and level flight, constant speed

ASI shows last speed measured when the system was functional

straight and lev-el flight, acceler-ated

ASI shows last speed measured when the system was functional, i.e. under-reading

straight and level flight, decelerat-ed

ASI shows last speed measured when the system was functional, i.e. over-reading

descent, con-stant speed

due to the increase in static pressure the ASI indica-tion decreases, i.e. progressive under-reading

climb, constant speed

due to the decrease in static pressure the ASI indica-tion increases, i.e. progressive over-reading

Table 2 (9 Marks)

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5. ATA 24 addresses the aircraft electrical system.

a) List three sources of electrical energy for aircraft.

engine generator, engine alternator, APU generator, APU alternator

battery, GPU

TRU, Inverter, IDG, APU (all 1 mark only)

(6 Mark) b) Between two electrical bus bars, such as the AC bus 1 and the AC bus 2 in figure 5, a component named bus tie is found. What is the purpose of the bus tie under normal opera-tions and contingency (i.e. ab-normal) operations.

Figure 5 electrical system panel Normal Operation: Under normal operating conditions the bus tie separates busses. Thus, the aircraft has redundancy and in case of the failure of one system, the other is not affected. Abnormal Operation: If one electrical system has failed, the bus tie can connect it to the redundant system and power the relevant bus from the opposite or alternative power source.

(6 Marks)

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c) Figure 6 shows a schematic layout of a bus bar and some electrical systems consuming electrical energy. Complete the drawing in figure 6 below and con-nect the systems such, that the bus bar is protected from short circuit and over current of each individual consumer.

(4 Marks) Figure 6 DC bus bar with consumers d) Name the element you are using in Figure 6 to protect the bus bar from short circuit and overload. Circuit Breaker (C/B 1 mark only) Fuse

(2 Marks)

6. Compare and contrast the characteristics of the magnetic compass and the di-rectional gyro indicator, by completing table 3:

Characteristic Magnetic Compass Directional Gyro

Orientation (i.e. points where)

magnetic North (1) free, can be aligned in any direction (1) typically magn. North (0.5)

Drift no drift (1) real drift (1) apparent drift (1)

Accuracy during turn turning error in North-South axis (2)

no turning error (1)

Accuracy during acceleration

acceleration error in East-West axis (2)

no acceleration error (1)

Sensitivity to interfer-ence (i.e. how sur-rounding materials in-fluence the accuracy)

Sensitive to Ferro metal-lic materials, magnetic materials and electrical currents (2)

not sensitive to interfer-ence (1)

Table 3 (14 Marks)

28

VD

C

electrically driven fuel pump

avionics cooling fan

flap control unit

R/H taxi light

individual connec-tion one C/B per con-sumer parallel connection alternative: fuse

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7. Figure 7 shows the ECAM fuel page of a twin-engine transport category aircraft.

Figure 7 ECAM fuel page a) Referring to figure 7 above, how much fuel is available in each tank and what is the total amount of fuel on board? List the information in table 4 below.

Tank Fuel [kg]

Center 0

Left Main 860

Right Main 780

Left Auxiliary 680

Right Auxiliary 620

Total 2 940

Table 4 (6 Marks) b) Currently the Auxiliary Power Unit (APU) is operating. Which tank is feeding it with fuel? Left Main tank (2 Marks)

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c) Considering that the Auxiliary Power Unit (APU) in figure 7 above is driven by a turboshaft engine, what type of fuel do you expect to be stored in the aircraft tanks? Jet Fuel, Jet A, Jet A1 Kerosin (1) (2 Marks) d) In figure 7 above, locate the cross feed valve and determine its position? open single mark if cross feed valve located (e.g. circled) (3 Marks) e) In figure 7 above, which tank feeds engine #2? Left Main tank (3 Marks) f) Explain your answer to question 7.e. What is the purpose of such a fuel routing? There is a fuel imbalance between the left and right main tanks Normally #1 engine would feed from the left main tank and #2 engine would feed from the right main tank, thus assuring redundancy With the cross feed operation the fuel imbalance can be corrected, though problems with the left tank fuel system would affect both engines (4 Marks)

--------------------------End Of Test-------------------------

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Working Space