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123 Cards in this Set
- Front
- Back
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What is the definition of chord?
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The longitudinal distance between the leading and trailing edges.
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What is mean chord?
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Average chord (distance between leading and trailing edge).
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What is aspect ratio?
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Relationship between span and chord.
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What is camber?
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Relationship between thickness and chord.
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What is MAC? What is it used for?
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Position of the C of G within an imaginary rectangle wing. Used to define whether lift/C of G couple is not too long for elevators.
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What is boundary layer?
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Layer above wing where air is stationary. Defined as distance where air reaches 99% of un-affected air speed.
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What is Vimd?
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Speed for L/D max.
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What is CAS?
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IAS corrected for pressure and instrument error.
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What is EAS? Which is greater?
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CAS corrected for compressibility error. EAS is always equal to or greater than CAS.
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Which airspeed uses F factor tables?
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EAS to correct for compressibility error.
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What is TAS?
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EAS corrected for air density error due temp not being ISA.
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Climbing at a fixed Mach will see what effects on IAS and TAS?
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IAS will decrease.
TAS will decrease. |
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What do Vmo and Mmo describe?
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Maximum normal operating speed.
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Climbing at a fixed IAS just below Vmo, will see .......................?
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Mmo eventually exceeded.
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What is the relationship between TAT and OAT?
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Total Air Temperature is always warmer than actual Outside Air Temperature.
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What is Vmcg?
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Minimum speed at which the pilot can maintain directional control of the aircraft with one engine suddenly becoming inoperative during take off roll with use of aerodynamic controls only.
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Name 6 factors that reduce Vmcg.
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High density altitude
De-rated take off power Large tail fin area Large rudder area/deflection Forward C of G Short distance from engine to fuselage |
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What is Vmca?
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Minimum speed with which pilot can maintain directional control of the aircraft when completely clear of ground and out of ground effect.
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In a propeller aircraft, which engine is the critical engine?
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One with the down going blade closest to the fuselage.
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In a jet aircraft, which engine is the critical engine?
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Upwind engine
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What will be the position of the skid ball if rudder and bank is used to counter-act asymmetric drag?
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Live side of centre.
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Best glide and holding speeds occur at ...............
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L/D max
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For a turboprop, best climb angle occurs at a speed ....................
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Less than L/D max
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For a turbojet, best climb angle occurs at a speed .........................
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Equal to L/D max
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For a turboprop, best rate of climb occurs at a speed ............................
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Equal to L/D max
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For a turbojet, best rate of climb occurs at a speed .............................
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Greater than L/D max
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What is the effect of increased weight on best angle and best rate of climb? Why?
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Increase. Due to increased weight causing an increase in induced drag. So greatest performance degradation will be at low speeds.
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What effect does increased altitude have on:
1. Thrust required? 2. Power required? 3. Airspeed for L/D max |
1. Same thrust required.
2. Increased power required. 3. Increased speed for best L/D |
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What is washout? What is it used for?
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Twisting of the wing so that the tips are at a lesser incidence angle than the roots. Used to encourage wing roots to stall first on a swept wing.
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How does leading edge slat deployment change the stall characteristics of a swept wing?
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At certain A of A/speed combinations, slats deploy on outboard leading edges to re-energise the flow over the tips.
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How do wing fences work? What are they used for?
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Inhibit the spanwise flow of air, and produce a trailing vortex.
Used on a swept wing to reduce wing tip stalling characteristics. |
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What are saw tooth/dog tooth? How do they work?
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A sudden change in chord length, showing as a notch in the wing.
Prevents spanwise flow, inhibiting wing tip stall characteristics on a swept wing. |
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What are vortilons? How do they work?
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Small fences fitted to underside of leading edge. Particularly useful at high angles of attack at reducing spanwise flow by shedding a vortex.
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What are vortex generators? How do they work?
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Small vertical plates that rise above wing surface. Re-energise the boundary layer and inhibit spanwise flow.
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What are shark teeth? How do they work?
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Fitted to inner leading edges close to wing root. Protrude into airflow near the stall angle causing the wing root to stall first.
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What three wing characteristics cause a sudden stall?
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Sharp nose, thin wing, max thickness and camber further aft.
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Leading edge slots:
1. Re-energise flow? 2. Increase stall angle/decrease stall speed? 3. Pitch up moment? 4. Change in camber? |
1. Yes
2. Yes 3. No pitch moment. 4. No camber change |
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Leading edge slats:
1. Re-energise flow? 2. Increase stall angle/decrease stall speed? 3. Pitch moment? 4. Change in camber? |
1. Yes
2. Yes 3. Pitch up moment 4. Increase camber |
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Leading edge flaps:
1. Re-energise flow? 2. Increase stall angle/decrease stall speed? 3. Pitch moment? 4. Change in camber? |
1. No
2. Yes 3. Pitch up moment 4. Increase camber |
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Under which conditions are leading edge devices most effective?
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High angles of attack.
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What happens to approach angle of attack and speed if LE devices are not deployed?
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Lower angle of attack.
Higher approach speeds. |
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All trailing edge flaps ..................... stall speed and produce.......................... pitching moment and ................... wing camber.
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Reduce the stall speed
Produce nose down pitch moment Increase wing camber |
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Which types of flaps increase wing surface area?
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Zap flaps, Fowler flaps, and slotted Fowler flaps.
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Which types of flaps re-energise the boundary layer?
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Slotted flaps and Fowler slotted flaps.
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What do tail mounted speed brakes do?
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Increases drag only.
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How do differential speed brakes operate?
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Spoilers extend and retract on different wings during a turn while speedbrakes are up.
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How do non-differential speed brakes operate?
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Spoilers on the inside of the turn only move during a turn while speed brakes are up.
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Inflight extension of speed brakes will cause .........?
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A buffeting similar to low speed stall buffet.
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What pitch moment will speedbrake deployment cause?
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Pitch up, as centre of lift moves forward.
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How do spoilers overcome aileron shortcomings?
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Make up for smaller ailerons.
Can be used on thin, swept wings which would twist if ailerons only were used (Aileron reversal) More useful than ailerons at high Mach numbers. |
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What is Mcrit?
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Free stream mach number at which first shockwave forms
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What is Mcdr?
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Free stream mach number at which marked drag rise occurs.
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Where does the shockwave first form?
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Where air slows over the wing to Mach 1.0. Form at wing root first.
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Which direction does the shockwave move as speed increases?
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Moves further rearward.
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What happens to the stagnation point as speed increases?
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It gets bigger.
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Which shockwave reaches the trailing edge first: top or bottom? Why?
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Bottom. It is not sowed down to the same extent as the top one by flow separation.
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What happens to the centre of lift as speed increases past Mach 1.0? What does this cause? How is this cause dealt with?
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Centre of lift moves rearward.
Causes pitch down moment (Mach tuck). Mach trimmer automatically adjusts for Mach tuck. |
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What happens to lift and drag after shockwave formation?
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Lift decreases and drag increases.
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How are "tail waves" formed?
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When both top and bottom shockwaves have reached trailing edge, they form wave (i.e. flow over entire wing is now supersonic).
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How are "bow waves" formed?
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Air ahead of wing is warmed due to compression heating. Increases speed of sound speed.
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What happens to bow wave as free stream mach number exceeds M1.0?
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Aircraft catches up to bow wave which moves closer to leading edge and (if leading edge is sharp) attaches to it. Called Mach detach (Mdet).
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What happens to the following airflow values through a normal shockwave?
1. Temperature 2. Pressure 3. Velocity 4. Mach number 5. Airflow direction change |
1. Rise
2. Rise 3. Drop 4. Drop 5. No change |
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What happens to the following airflow values through a oblique shockwave?
1. Temperature 2. Pressure 3. Velocity 4. Mach number 5. Airflow direction |
1. Rise
2. Rise 3. Drop 4. Drop 5. Change! |
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At what point do the low speed stall speed and high speed stall speed meet?
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Aerodynamic ceiling
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What 2 factors affect aerodynamic ceiling?
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Turbulence and bank angle (i.e. apparent weight).
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Considering swept wing vectors, what are V, V1 and V2 and what do they represent?
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V parallel to airflow. (free stream mach number)
V1 right angles to leading edge (Mcdr and Mcrit) V2 parallel to trailing edge |
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What are two disadvantages of swept wings?
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Wing tip and dangerous nose-up tendency stall
Less lift |
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What are two advantages of swept wings?
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Higher Mcrit and Mcdr values
Increase lateral stability |
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How does the Lift/AofA graph of a swept wing differ from a normal wing?
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Lift is lower at all angles of attack.
Point of maximum lift occurs at a higher angle of attack. |
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What effects do thin wings have on Mcrit, Mcdr, lift and drag?
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Higher Mcrit
Higher Mcdr Lower lift at all angles of attack Lower drag at all angles of attack |
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What effect do vortex generators have on Mcrit and Mcdr?
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Higher Mcdr
Same Mcrit |
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What effect do Kuchemann Carrots have?
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Break up the shockwave
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What is the purpose of glove fairings?
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Increase wing sweep at the wing root, delaying Mcrit in this area.
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How many Q feel systems are in the B767? What does this system do?
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2
Provides artificial feedback to pilot yoke when using elevators. |
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Which controls have a ratio changer? How does this system work?
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Rudder.
De-sensitises rudder deflection for a given rudder pedal force. |
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What are the two different yaw damper systems? How do they differ?
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Series yaw damper: rudder pedals do not move in association with yaw damper units.
Parallel yaw damper: rudder pedals move in association with yaw damper unit. |
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Which inputs do the yaw damper systems use?
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CADC
IRS |
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What is the secondary function of the yaw damper system?
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Provide rudder inputs to balance turns. Skidball remains in centre.
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What are the normal and back up actuating methods for operating flaps and slats?
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Normal: centre hydraulic system
Back up: electrical (much slower) |
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What happens if one wings high lift devices are extending at a different rate to the other?
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Flap/slat asymmetry monitoring system stops flaps being extended further.
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What are the three pre-conditions that must occur before armed spoilers will extend after landing?
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1. There is hydraulic pressure to both landing gear bogie tilt actuators.
2. Both of the bogie tilt sensor have detected a NO-TILT condition 3. Both thrust levers are in the IDLE position. |
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When will spoilers extend if all other pre-conditions are met, but they are not in the ARMED position?
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Reverse thrust is applied.
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What are the three methods of stabiliser trim control? Which has priority?
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Electric (control yoke)
Automatic (AP) Manual/alternate (trim levers) - PRIORITY |
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When will pushing the yoke trim button disengage the AP?
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One AP engaged, above 1500ft radio altitude.
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How can the pilot stop un-commanded stabiliser movement?
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Trim cut-off switch or moving control column in opposing direction to stabiliser.
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When would a STAB TRIM message show on the EICAS system? What safety protocols are active after that message?
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Stabiliser trim brake fails to release.
Continued use of electric trim will be at half normal rate. If both stabiliser brakes are engaged, no stabiliser trim available. |
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What happens when a rudder ratio change fault develops?
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Left hydraulic system to rudder is depressurised to restrict rudder deflection and provide structural protection at high airspeed.
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What happens with the loss of one yaw damper?
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Rudder yaw authority is reduced by one half.
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When using the alternate flap/slat extension system (electric) which protections are not available?
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Flap asymmetry and flap load relief protection.
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What effect will failure of leading edge devices have on angle of attack and speed on approach?
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Lower angle of attack
Higher speed |
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What effect will failure of trailing edge devices have on angle of attack and speed on approach?
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Higher angle of attack
Higher speed |
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Which type of flap can be described as:
Part of the rear underside of the wing hinges down. |
Split flap
- increase camber |
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Which type of flap can be described as:
Part of the rear underside of the wing moves rearwards and down when deflected. |
Zap flap
- increase camber - increase wing area |
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Which type of flap can be described as:
A slot opens when deployed. |
Slotted flap
- re-energises flow - increase camber |
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Which type of flap can be described as:
Part of the rear underside of the wing moves rearwards and downwards, and a slot is provided to inhibit airflow separation. |
Fowler flap
- re-energises flow - increases wing area - increases camber |
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Describe the Coefficient of Lift vs Angle of Attack graphs of plain wing, TE flaps only, LE slots/slats only and TE and LE.
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Plain wing is normal lift graph.
LE only is extension of plain wing graph TE only is extension of plain wing but higher at all angles of attack. TE and LE is extension of TE only graph. |
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What are the four advantages of a trimming stabiliser?
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1. Less drag created.
2. Full elevator movement preserved 3. Greater trimming authority 4. Better trim control at range of speeds |
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Why must extra care be taken when using a trimming stabiliser?
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Elevator may not be able to overcome effect of trim if set incorrectly for take off.
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What happens to the C of G when burning fuel from the centre tank?
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Moves aft
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What happens to the C of G when burning fuel from the wing tanks?
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Moves forward
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Does the aircraft feel heavy and unresponsive with a C of G well forward or well aft?
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Well forward.
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What conditions may cause a stalled stabiliser drive?
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Turbulence. I.e. during downdraft, trim moves well aft and a subsequent sudden change could cause stabilser drive to stall.
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What can the pilot do if the stabiliser has seized?
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Use reduced flap for landing and a higher landing speed.
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When flying manually, which controls does the Mach trimmer work through?
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Stabiliser only.
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When flying with AP engaged, which controls does the Mach trimmer work through?
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Stabiliser and elevator.
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What is the purpose of winglets?
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Reduce spilling of air at the tips and reduce downwash by shifting vortices well above wing.
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What are the 3 disadvantage of winglets?
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Increase parasite drag
Increase wing loading at the tip May increase dutch roll tendancy |
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How does centre of gravity effect longitudinal stability?
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C of G ahead of the centre of lift = positive longitudinal stability.
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How do thrust lines effect longitudinal stability?
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High thrust line = positive longitudinal stability.
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What is the primary source of directional stability?
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The vertical fin
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What effect do aft body strakes have on stability?
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Increase directional stability
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What effects do high forward airspeed and altitude have on directional stability?
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Direction stability decreases
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What effect does a dorsal fin extension have on stability?
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Increases directional stability at large sideslip angles
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Do high wing or low wing designs have better lateral stability?
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High wing
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What is the primary source of lateral stability?
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Wing dihedral
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Do swept wings increase or decrease lateral stability?
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Increase
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Does flap deployment increase or decrease lateral stability?
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Decrease.
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What stability characteristics are associated with spiral divergence?
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Directional stability is large compared to lateral stability.
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What stability characteristics are associated with dutch roll?
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Lateral stability is large compared to directional stability.
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When is dutch roll most prevalent?
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When developing high lift values. High altitude and high speeds.
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When is spiral instability most prevalent?
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Low altitude.
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What factors is turn radius effected by?
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Velocity / Angle of Bank
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What factors is turn rate effected by?
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Angle of Bank / Velocity
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