Instrumention and Aircraft Tech Flashcards
How does temperature affect LSS?
As temp decreases, LSS decreases.
What are the ASI/Mach Meter indications for a blocked Pitot and or static port?
A blocked static line means that the static pressure in the ASI/Mach Meter remains the same.
What are the forces acting on an aircraft in flight?
Drag, thrust, lift and weight.
What is direct lift control?
The elevator, stabiliser produces direct lift control.
What are high lift devices?
Trailing edge flaps, leading edge flaps, slots.
Define two major types of drag…..
Profile and induced drag. Together they equal total drag.
What are high drag devices?
Landing gear, trailing edge flaps, spoilers, reverse thrust, breaking parachute.
How do you prevent span-wise airflow on a wing?
Fences, vortex generators.
What is the purpose of fences and vortex generators?
To reduce span-wise airflow and thereby reduce its effects.
What are winglets and how do they work?
Winglets are aerodynamically efficient surfaces. They are designed to reduce the effect of span wise airflow and reduce induced drag by dispensing the the airflow from the upper and lower surfaces of the wing.
How does a forward centre of gravity affect the stall speed?
A centre of gravity forward of the centre of pressure will cause a higher stall speed.
What are the advantages of a swept wing?
High Mach cruise speed and stability in turbulence.
Where does a swept wing stall first?
A simple swept or tapered wing will stall at the wing tip first.
Explain speed stability…..
It is the behaviour of the speed of the aircraft after a disturbance at a fixed power setting.
What is a Mach number?
Mach number is a true airspeed indication, given as a percentage relative to the local speed of sound.
What is Mcrit?
Mcrit is the critical Mach Number. It is the speed at which the airflow over the wing becomes sonic.
What is Mach Tuck?
It is the nose down pitch moment an aircraft experiences as it passes its critical Mach number.
What is the purpose of a Mach trimmer?
A Mach Trimmer automatically compensates for Mach tuck above Mcrit.
What are the effects of compressibility?
The effect of air being compressed onto a surface resulting in an increase in density and thus dynamic pressure rises above its expected value.
What changes the aircrafts angle of attack at the stall?
The movement of the centre of pressure point at the stall causes a change in the aircrafts angle of attack.
What happens to the stall speed at very high altitudes?
Mach number compressibility effect on the wing results in a higher EAS. Compressibility error on the IAS increases the stall speed.
What is a super stall?
It is a stall from which the aircraft is unable to recover.
What is Dutch Roll?
It is an oscillatory instability. It is a combination of yawning and rolling motions.
What causes Dutch Roll?
Swept wings.
What are the three purposes of spoilers?
Roll control, air speed brakes, ground lift dumpers.
What are Kruger flaps?
Krueger flaps are leading edge wing flaps used to increase the wing camber.
How does the use of flaps affect take off ground run?
A higher flap setting within the take off range will reduce the ground run required.
What is the purpose of yaw and roll dampers?
To prevent Dutch Roll and coordinate turns.
What are the four reasons for a variable incident tail plane?
To provide a balancing force for a large CofG range, cope with large trim changes, provide balancing force for a large speed range and reduce elevator trim drag.
What is a mass balance?
It is another form of aerodynamic balance control on a control surface.
What are active controls?
A surface that moves automatically/actively in response to non-direct inputs.
What is engine torque?
A force causing rotation.
What is specific fuel consumption?
The quantity/weight (lbs) of fuel consumed per hour divided by the thrust of an engine in pounds.
Why do operators use reduced de-rate thrust takeoffs?
To protect engine life, improve reliability and reduce noise.
What is the purpose of engine relight boundaries?
To ensure that the correct proportion of air is delivered to the engines combustion chamber to restart the engines in flight.
Why are bleed valves fitted to gas turbine engines?
To provide bleed air for auxiliary systems, to regulate the correct airflow pressures between different engine sections.
What fuels are commonly used on jet aircraft?
Jet A and Jet A1
Is there a critical engine on a jet aircraft?
No.
How does INS/IRS find true north?
It is aligned to true north by its gyroscopes.
What are the advantages of an INS? (4 items)
Very accurate, self contained system, totally global system enabling aircraft to fly great circle tracks.
What are the disadvantages of INS? (3 items)
Bounded errors, unbounded errors, inherent system errors.
What does the rudder PSI reducer do?
Takes the stress of the tail fin.
What effect does slats have on the angle of attack?
The angle of attack will increase.
What affect does a 60 degree bank turn have on the stall?
The stall speed increases by approximately 40%.
What happens in a jet engine compressor section?
The compressor, which rotates at very high speed, adds to the airflow whilst at the same time squeezing it in to a smaller space, thereby increasing temperature and pressure.
For a given airspeed how does you rate of decent vary with weight?
An increase of weight will increase your rate of decent and vice versa.
What is parasite drag?
Parasite drag is made up of pressure and skin friction drag. Parasite drag is caused by any aircraft surface which deflects or interferes with the smooth airflow around the aeroplane.
The lift generated by a wing varies with angle of attack such that it?…..
Produces maximum lift just before the stall angle is reached. When an aircrafts wing reaches the stall angle, the wing stops generating lift.
Des a compressor change kinetic energy in to pressure energy? If so are the stators divergent or convergent?
Yes, however an axial flow compressor on modern turbofan engines uses a series of convergent and divergent ducts.
Whilst maintaining a constant altitude, what is the effect of flaps and slats on the angle of attack?
The angle of attack will decrease.
Why do modern jets have a swept wing?
To permit a high Mach cruise number along with low drag.
What are the aerodynamic effect of a swept wing?
High Mach cruise speeds and stability in Turbulance.
What is the relationship between altitude and performance of a jet engine?
They both decrease with altitude.
What is more efficient, a forward or aft CofG?
Aft. This is because it reduces tail plane force which reduces aerodynamic drag.
High bypass turbofan engines are used on commercial aircraft because….?
The overall noise signature of advanced turbofan engines with highly loaded wide chord fan blades is significantly less than previous older technology engines.
Why are aircraft fitted with negative pressure valves?
A negative pressure relief valve prevents external atmospheric pressure from exceeding internal cabin pressure.
Flying west bound in RVSM what is the lowest level in RVSM airspace?
FL300
Flying on a heading 110deg what is the highest RVSM level you can fly at?
FL410
When you would you select anti ice on?
Icing conditions exist: when the OAT on the ground and for takeoff, or TAT in-flight, is 10°C or below, and visible moisture in any form is present (such as clouds, fog with visibility of one mile (1500 m) or less, rain snow, sleet and ice crystals). Icing conditions also exist when: the OAT on the ground and for takeoff is 10°C or below when operating on ramps, taxiways or runways where surface snow, ice, rain standing water, or slush may be ingested by the engines or freeze on engines or nacelles.
Flying towards an ADIZ area what must you do?
Comply with local state regulations.
What are the CAT I limits?
A decision height not lower than 200 feet above touchdown zone elevation, and with either a visibility not less than 800 metres, or a runway visual range not less than 550 metres
Standard taxiway lights exiting a runway?
Green
How far from the end of the runway do the centreline lights turn from red/white to solid white?
900 meters
What are the high and low speed buffet margins?
1.3g - 1.15g
What is the standard safety manoeuvre margin?
1.3g
Flying into a known area of turbulence what must you do?
Start Switches to FLT, Speed M.73/280kts, Seat Belt Signs On (Secure Cabin), Stop Cabin Service
What type of cloud would you expect turbulence?
From the options given, Lenticular (Strong turbulence beneath cloud)
After landing what is the most effective way of stopping?
Anti-skid breaking
Why are aircraft fitted with inboard ailerons?
To stop the wing twisting.
You land on a contaminated runway and start sliding. What are your actions?
Cancel reverse thrust and regain the centreline.
You are acting as Pilot Monitoring and call “100 Above” but there is no reply. What do you do?
Call again. If there is no response assume control.
The price of fuel is high. What cost index would you use (Low, Medium or High)?
Low (‘0’ gives maximum range airspeed and minimum trip fuel)
The ‘payload’ on an aircraft consists of?
Passengers, Mail & Freight (definition: a cargo, or the part of a cargo, producing income)
Where is it most appropriate to jettison fuel?
Over the sea and above FL100
What is the relationship between V1 and Vmcg?
Vmcg must be less than or equal to V1
What are the factors that determine optimum cruise speed?
Altitude, OAT, Weight & Centre of Gravity
What is RNP4?
Accuracy +/-4nm (95% of the time)
What is windshear?
Deviations from target conditions of: +/-15kt IAS, +/-500fpm, (+/-5° pitch attitude, +/-1dot glideslope displacement or unusual throttle position for a significant period)
What is the most effective way of stopping the aircraft at HIGH speed?
Reverse thrust.
What is the maximum time permitted for a Jet Engine to spool up from idle to full thrust?
8 seconds
If when flying at 39,000 feet you found the static outside air temperature to be -47.5C. The deviation from the international Standard Atmosphere would be?
15.5
Take the Height x 2 -15.
So 39 x 2 = 78
78 - 15 = 63
63 - 47.5 = 15.5
