A free Premium account on the FCL.055 website! Read here
Sign up to unlock all our services and 15164 corrected and explained questions.
Question 267-1 : Flaperons are controls which combine the function of ? [ Theoretical lift off ]
Ailerons and flaps.
Question 267-2 : In general transport aeroplanes with power assisted flight controls are fitted with an adjustable stabiliser instead of trim tabs on the elevator. this is because ?
Effectiveness of trim tabs is insufficient for those aeroplanes.
Question 267-3 : A jet aeroplane equipped with inboard and outboard ailerons is cruising at its normal cruise mach number. in this case ?
Only the inboard ailerons are active.
.the ailerons are normally situated at the wing tip, to give the greatest moment for the force produced. however this also means that they cause the maximum twisting and bending loads on the wing. this can cause a loss of effectiveness or even reversal of the aileron..to reduce these effects the ailerons can be mounted further inboard. alternatively, two sets of ailerons may be fitted, one set at the wing tip for use at low speeds when the forces involved are low, and one set inboard for use at high speeds when the forces are greater and could cause greater structural distortion. in summary, outboard ailerons are low speed ailerons and inboard ailerons are high speed ailerons and only the inboard ailerons are used when the flaps are retracted.
Question 267-4 : Which of the following statements concerning control is correct ?
In a differential aileron control system the control surfaces have a larger upward than downward maximum deflection.
.to generate lift we have to move air downwards, and to roll into a banked attitude to turn we have to lift one wing while dropping the other. to lift a wing we have to generate more lift and so we lower the aileron on that side, we don't get something for nothing and so this extra lift increases the drag, meanwhile dropping the other wing by moving the aileron upwards reduces the drag. the increased drag generated by the down going aileron causes the nose to yaw in the opposite direction to the roll and this is called adverse yaw.. /com en/com080 300a.jpg..with differential ailerons, one aileron is raised a greater distance than the other aileron is lowered for a given movement of the control wheel. this produces an increase in drag on the descending wing. the greater drag results from deflecting the up aileron on the descending wing to a greater angle than the down aileron on the rising wing. while adverse yaw is reduced, it is not eliminated completely.. /com en/com080 300b.jpg..
Question 267-5 : When are outboard ailerons if present de activated ?
Flaps and slats retracted or speed above a certain value.
Question 267-6 : Which statement about stick force per g is correct ?
The stick force per g must have both an upper and lower limit in order to ensure acceptable control characteristics.
Question 267-7 : Examples of aerodynamic balancing of control surfaces are ?
Servo tab, spring tab, seal between the wing trailing edge and the leading edge of control surface.
Illustration of a seal between the wing trailing edge and the leading edge of control surface. 2762.when you move the control surface, it generates an area of high pressure and an area of low pressure...this differential pressure creates a compensation force acting in the same way of the pilot's action.
Question 267-8 : Which phenomenon is counteracted with differential aileron deflection ?
Adverse yaw.
To generate lift we have to move air downwards, and to roll into a banked attitude to turn we have to lift one wing while dropping the other. to lift a wing we have to generate more lift and so we lower the aileron on that side, we don't get something for nothing and so this extra lift increases the drag, meanwhile dropping the other wing by moving the aileron upwards reduces the drag. the increased drag generated by the down going aileron causes the nose to yaw in the opposite direction to the roll and this is called adverse yaw....with differential ailerons, one aileron is raised a greater distance than the other aileron is lowered for a given movement of the control wheel. this produces an increase in drag on the descending wing. the greater drag results from deflecting the up aileron on the descending wing to a greater angle than the down aileron on the rising wing. while adverse yaw is reduced, it is not eliminated completely.
Question 267-9 : An aeroplane has a servo tab controlled elevator. what will happen if the elevator jams during flight ?
Pitch control sense is reversed.
. /com en/com080 378.jpg.only the tab is left functioning. it is not connected to the elevator but works in the unnatural sense to drive the elevator in the natural sense, so with the elevator locked you only have very limited control from the tab only and in the unnatural sense and, of course, you have no trim or balance fuction left.
Question 267-10 : A horn balance in a control system has the following purpose ?
To decrease stick forces.
.a horn balance is a method of aerodynamic balancing for the ailerons, elevators and rudders, and is used to produce a balancing moment in order to reduce amount of force required to move the controls..flutter is prevented by the use of mass balancing by adding weights to the control surface to move their cg , not by horn balancing...example of horn balance. 1537
Question 267-11 : An increase in geometric dihedral in a steady sideslip condition at constant speed would ?
Increase the required lateral control force.
Stability is the ability of the aircraft to return to equalibrium without input from the pilot..equalibrium is where all the forces are zero...it does not mean that the aircraft returns to the same heading, or altitude, but that the relative airflow is in such a position that the aircraft will be balanced. in the question, we are trying to hold the aircraft in a steady side slip, which means we are holding the aircraft out of equalibrium..a stable aircraft with geometric dihedral will try to oppose this...so we will be required to hold greater forces to maintain the angle which is opposing the natural tendency of the aircraft..if we increase the geometric dihedral even further, we will need more effort to hold that sideslip as stability will be increased.
Question 267-12 : When a jet transport aeroplane takes off with the cg at the forward limit and the trimmable horizontal stabiliser ths is positioned at the maximum allowable nose down position for take off ?
Rotation will require a higher than normal stick force.
Question 267-13 : Which statement is correct.i. on fully hydraulic powered flight controls there is no need for mass balancing.ii. on fully hydraulic powered flight controls there is no need for trim tabs. ?
I is incorrect, ii is correct
.flight control force balance can normally be achieved hydraulically as part of the actuator sizing. you have to remember that even though fly by wire aircraft receive their control inputs electronically, the control surfaces are still powered by the hydraulic system s which are sized to overcome mass balance and flight loads. but, to prevent flutter, mass balancing is required, and also in case of manual reversion total hydraulic failure...and with a fully hydraulic powered flight controls there is no need for trim tabs, you can move the controls where you like and use an artificial trim.
Question 267-14 : An aeroplane performs a right turn, the slip indicator is left of neutral. one way to co ordinate the turn is to apply ?
More left rudder.
.in a skidding turn the ball will be displaced in the opposite direction of turn in the direction of turn for a slipping turn.. /com en/com080 593.jpg..one way to co ordinate the turn is to apply more left rudder.
Question 267-15 : When roll spoilers are extended, the part of the wing on which they are mounted ?
Experiences a reduction in lift, which generates the desired rolling moment. in addition there is a local increase in drag, which suppresses adverse yaw.
Question 267-16 : When power assisted controls are used for pitch control ?
A part of the aerodynamic forces is still felt on the column.
Question 267-17 : The pitch angle is defined as the angle between the ?
Longitudinal axis and the horizontal plane.
. 682.the angle of attack should not be confused with the pitch angle or attitude of aircraft, which are angles relative to the horizontal while the angle of attack is in respect to the relative airflow.
Question 267-18 : Which statement in respect of a trimmable horizontal stabiliser is correct ?
An aeroplane with a forward c.g. requires the stabiliser leading edge to be lower than for one with an aft c.g. in the same trimmed condition.
. 1567.if the cg is moved aft, it results in a larger nose down pitching moment which has to be compensated for by placing a download on the tailplane. this can be achieved by deflecting the elevator up, although this results in high trim drag at higher airspeeds. on large aircraft small movements of the variable incidence stabiliser allow the trimming to be carried out, but with reduced trim drag...an upward deflection of the elevator is required to trim the aircraft, so think of the stabiliser as a large elevator with its trailing edge moving in the same direction as the elevator. to achieve this you must therefore lower the leading edge of the stabiliser to produce the necessary download...note once in a trimmed condition on fully powered flying controls the elevator will then align itself with the stabiliser to reduce the tail load and also the loads acting on the hinges and servo actuator. on power assisted controls there is however no guarantee that this occurs due to downwash and configuration effects that can alter the flow over the surface. it is also fair to say that trim drag also increases fuel consumption.
Question 267-19 : An example of differential aileron deflection during initiation of left turn is ?
Left aileron 5° up. right aileron 2° down.
. /com en/com080 510.jpg.the aileron linkage causes the up going aileron the move through a larger angle than the down going aileron. this increases the drag on the up aileron, and reduces it on the down aileron, and so reduces the difference in drag between the two wings.
Question 267-20 : An aeroplane is provided with spoilers and both inboard and outboard ailerons. roll control during cruise is provided by ?
Inboard ailerons and roll spoilers.
Question 267-21 : Mass balancing of control surfaces is used to ?
Prevent flutter of control surfaces.
.flutter is a dangerous phenomenon encountered in flexible structures subjected to aerodynamic forces. as the airspeed increases, there may be a point at which the structural damping is insufficient to damp out the motions which are increasing due to aerodynamic energy being added to the airfoil. this vibration can cause structural failure and therefore considering flutter characteristics is an essential part of designing an aircraft.. 813.to counteract this phenomenon, the control surface's cg must be as close as possible of the hinge the torsion axis.
Question 267-22 : In what phase of flight are the outboard ailerons if fitted not active ?
Cruise.
Question 267-23 : The most important factor determining the required position of the trimmable horizontal stabiliser ths for take off is the ?
Position of the aeroplane's centre of gravity.
Question 267-24 : What is the position of the elevator in relation to the trimmable horizontal stabiliser of an aeroplane with fully hydraulically operated flight controls that is in trim ?
Elevator deflection is zero.
.a fully hydraulically operated flight controls is an irreversible system, and the trim is a redatum, as there is no physical connection between the stick and control. therefore there will be no elevator deflection when trimmed.
Question 267-25 : In straight flight, as speed is increased, whilst trimming to keep the stick force zero ?
The elevator is deflected further downwards and the trim tab further upwards.
. /com en/com080 641.jpg
Question 267-26 : Rotation around the longitudinal axis is called ?
Rolling.
. /com en/com080 547a.jpg
Question 267-27 : Rotation around the normal axis is called ?
Yawing.
. /com en/com080 547a.jpg
Question 267-28 : Which of these statements about a trimmable horizontal stabiliser is correct ?
A trimmed aeroplane with an aft cg requires the stabiliser leading edge to be higher than in the case of a forward cg in the same condition.
. /com fr/com080 298.jpg.with a forward cg, the tailplane must produce a high downward force to stabilise the aircraft. if the cg moves aft closer to the centre of lift the downward force is reduced, the.trimmable horizontal stabiliser leading edge is higher than in the case of a forward cg, to keep the balance of lift and total weight constant.
Question 267-29 : When comparing an elevator trim system with a stabiliser trim system, which of these statements is correct ?
An elevator trim is more sensitive to flutter.
.on a stabiliser trim system, the whole tailplane is moving. this large surface is less sensitive to flutter than an elevator trim system. the elevator trim tab system is a small auxiliary control surface hinged at the trailing edge of the elevators.
Question 267-30 : When comparing a stabiliser trim system with an elevator trim system, which of these statements is correct ?
An elevator trim is less suitable for aeroplanes with a large cg range.
.a horizontal trimmable stabiliser enables a larger cg range, and is more suitable to cope with the large trim changes generated by the high lift devices on most jet transport aeroplanes..on a stabiliser trim system, the whole tailplane is moving. this large surface is less sensitive to flutter than an elevator trim system. the elevator trim tab system is a small auxiliary control surface hinged at the trailing edge of the elevators.
Question 267-31 : Comparing the differences between a horizontal trimmable stabiliser and an elevator trim tab, which of these statements are correct or incorrect.i. the effects of a stabiliser trim runaway are more serious..ii. a jammed trim tab causes less control difficulty. ?
I is correct, ii is correct.
.the effects of a trim tab runaway are more serious > wrong...the effects of a stabiliser trim runaway are more serious > correct..a jammed stabiliser trim causes less control difficulty > wrong...a jammed trim tab causes less control difficulty > correct..stabiliser trim runaway is more serious because it requires more force to be exerted by the pilot to overcome the movement of the stabiliser trim. because stabilisers pivot around a central hinge point, they are extremely sensitive to control inputs and aerodynamic loads. antiservo tabs are incorporated on the trailing edge to decrease sensitivity. they deflect in the same direction as the stabilisator. this results in an increase in the force required to move the stabiliser...whereas a jammed trim tab is less serious because it requires less force to be exerted by the pilot in order to overcome it.
Question 267-32 : Which aerodynamic design features can be used to reduce control forces ?
Horn balance, balance tab, servo tab.
Question 267-33 : In general, control forces are reduced by ?
A horn balance, servo tab and spring tab.
Question 267-34 : What are the primary roll controls on a conventional aeroplane ?
The ailerons.
Question 267-35 : Artificial feel is required ?
With fully powered flight controls.
Question 267-36 : Consider an aeroplane with.1. a trim tab..2. fully powered hydraulic controls and an adjustable horizontal stabiliser..for both cases and starting from a trimmed condition, how will the neutral position of the control column change, after trimming for a speed increase ?
1 moves forward, 2 does not change.
.after trimming for a speed increase.. the neutral position of the control column moves forward with a trim tab.. the neutral position of the control column with a fully powered hydraulic controls and an adjustable horizontal stabiliser...when speed increases, the pilot need to increase back pressure on the pitch control. this moves the elevator up. to hold the elevator in this new position, the trim tab is moved down..but with fully powered hydraulic controls, trimming does not reduce the effective range of pitch control, as the elevator remains approximately neutral when the aircraft is trimmed.
Question 267-37 : The tab in the figure represents.. err a 081 946 ?
A servo tab.
Question 267-38 : The tab in the figure represents.. err a 081 947 ?
A balance tab that also functions as a trim tab.
Question 267-39 : When comparing a stabiliser trim system with an elevator trim system, which of these statements is correct ?
A stabiliser trim is able to compensate larger changes in pitching moments.
Question 267-40 : Spoilers mounted on the wing upper surface can be used to ?
Assist the ailerons.
~
Exclusive rights reserved. Reproduction prohibited under penalty of prosecution.
