Engine and Prop

Question 1

Model of the Texan engine

Answer 1

PT6A-68 free turbine engine

Question 2

Model of the Texan engine

Answer 2

PT6A-68 free turbine engine

Question 3

SHP of the engine

Answer 3

1100

Question 4

What comprises the compressor stage

Answer 4

4 stage axial, 1 stage centrifugal

Question 5

How many fuel lines lead to the combustion chamber, and why?

Answer 5

2 fuel lines

Means they can be opened one at a time during engine start to gradually introduce fuel in to the engine whilst N1 is low, preventing a hot start.
Visibily seen as two spikes of ITT during engine start.

Question 6

Where is bleed air taken from and how many ducts are there?

Answer 6

End of the compression stage

2 - One for ECS (on top of the engine) and one for OBOGS (on the bottom)

Question 7

Why can an issue with the HP fuel pump affect the oil scavenge pump, and vice versa?

Answer 7

They run off the same shaft in the accessory gearbox

Question 8

Where is the hydraulic pump located?

Answer 8

At the back of the engine.

Begins producing hydraulic pressure as soon as the engine starts turning.

Question 9

How is the Torque value on the EICAS calculated?

Answer 9

A phase shift TQ probe measures the RPM of the power shaft.

Prop Interface Unit (PIU) measures prop shaft RPM and does the math to calculate TQ.

Question 10

What is the ratio of the reduction gearbox?

Answer 10

15:1

Question 11

If you have to abort an engine start and fuel flow has taken place in to the engine, what must you do?

Answer 11

A dry crank, obeying starter limitations

Question 12

How is the PMU powered?

Answer 12

Permanent Magnet Alternator (PMA)
32 V AC (PMU converts to 28V DC)
Or
When the PMA fails or Np < 40-50%, the PMU reverts to the 28V DC Bat Bus

Question 13

Which throttle is connected to the Fuel Management Unit (FMU) and how is it connected?

Answer 13

Front throttle via a flexible mechanical linkage

Question 14

What N1 setting does the PMU command the FMU to set for IDLE on the ground and why?

Answer 14

60% to avoid ground resonance with the prop

Question 15

What N1 value does the PMU command the FMU to set for IDLE in the air?

Answer 15

67%

Question 16

Does the PMU monitor, and if necessary abort, engine starts carried out in the air in the case of a relight?

Answer 16

No

Question 17

Under what conditions will the throttle microswitch give you a gear warning?

Answer 17

Gear up
<120kts
Flaps UP or T/O

Note - Will not warn if the flaps are at LAND

Question 18

If the St Rdy caption extinguishes during the engine start sequence, what does this indicate and what should you do?

Answer 18

The PMU will no longer control the start. You should move the throttle to OFF to abort the start and, obeying starter limitations, try again.

(Dry crank if necessary due to fuel inflow)