Aircraft Systems

Question 1

Tell me about GPWS

Answer 1

GPWS is a system used to warn pilots if their aircraft is in immediate danger of flying into the ground or an obstacle. GPWS relies on the A/C RadAlt, which determines the A/C height by bouncing a radar signal off the ground and measuring the duration of the trip.
EGPWS (Enhanced) uses A/C inputs such as position, altitude, speed glide slope and an internal terrain/obstacle database to predict a potential conflict between the flight path and terrain or an obstacle.

EGPWS will also talk to the TCAS of an aircraft so it won’t command a descent with terrain below.

Modes:
Excessive Sink Rate
Excessive Terrain Closure Rate
Altitude loss after T/O with a high power setting
Unsafe terrain clearance
Excessive deviation below glide slope
Excessively steep bank angle
Windshear Protection

Question 2

TCAS questions symbols, times etc

Answer 2

Traffic Collision & Avoidance System
Used for detecting and tracking other aircraft in your vicinity. It interrogates other A/C transponders & analyses the reply to determine range, bearing and relative altitude.
If a possible collision exists, it issues visual & audible advisories for vertical avoidance.

Open White Diamond - Greater than 1200’ or 6nm - Not a threat.
Filled White Diamond - Within 1200’ and 6nm - Still not a threat.
Filled Yellow Circle (TA) - Considered potentially hazardous. CPA is between 20-48 Seconds. A TA will precede an RA by 15 seconds.
Filled Red Square (RA) - Collision threat. CPA now within 15-35 Seconds. Initial reaction must be within 5 seconds and 2.5 seconds for a reversal. Follow commands of voice and fly green area of VSI.

Question 3

On the 777 which tank would you use first and why?

Answer 3

Centre tank is used first. It is for structural integrity, not of the fuel tank itself but of the general airframe - having fuel in the centre tank increases the load on the landing gear and makes the wings lighter, which means they bend more in flight (not good). Thus, if all the fuel that’s needed can be accommodated in the wings, the centre tank will be left empty. If there’s fuel in the centre tank, it will be burned off first, then the wing tanks will be burned off.

Question 4

Tell me about, Starter, Hydraulic pumps, aux fuel pumps etc… similarity to my current aircraft?

Answer 4

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Question 5

Tell me about the A330 fuel system? Trim tanks? Why?

Answer 5

Always fed to engine from the inner tanks.
Transfer sequence is:
- Centre tank to inner tank
- Inner tank down to 4000kg
- Trim/Stab tank to inner tank
- Inner tank down to 3500kg
- Outer tank to inner tank

Trim tank controls the A/C CoG.
The system either transfers fuel to the trim tank (aft) or from the trim tank (fwd). This movement alters the CoG. When the A/C is in cruise, the system optimises the CoG position to increase fuel economy by reducing drag. Normal operation is automatic, but the crew can manually select a fwd transfer is required.

Question 6

A330 Hydraulic system?Redundancy? How many?

Answer 6

3 Independent continuously operating systems. Green, Blue & Yellow each supplied by their own reservoir.

Question 7

Tell me about Fly by wire? What won’t it let you do?

Answer 7

1

Question 8

What does the aircraft have to combat Icing? Do we have boots? Tell me about bleed air. How does that help the anti-icing.

Answer 8

1

Question 9

Flying straight and level, static port gets blocked. We start descending. What happens to altimeter? ASI?

Answer 9

Static Port Blocked - Altimeter will remain at current altitude and VSI will remain on Zero.

Question 10

What’s the difference in how the 777 produces thrust compared to a turbo prop?

Answer 10

1

Question 11

What are vortex generators?
How do they work?
What do they do?
What phases of flight are they most beneficial? Why?
Where on the wing are they located?

Answer 11

Vortex Generators are small components deployed on the wing & stab surfaces. They modify the flow around them by affecting the boundary layer. They work by creating a swirling wake which places energy into the boundary layer of the wing. Results in a higher critical angle of attack, a lower stall speed and gentle stall characteristics.
They're placed in the transition regions of the boundary layer.
Benefits:
- Shorter T/O
- Lower stall speed
- Lower Approach Speed
- Higher AoA
- Increase Stability
- Higher RoC
- More effective control

Question 12

What would happen if fuel gets stuck in the trim tank?

Answer 12

Could results in the CofG being too rearward on landing and be outside of the CofG envelope.