601D Engine

Question 1

DEC/EDECU functions

Answer 1

IN FLT HOTT

Isochronos NP governing.
NP Reference (96-100)
Fault indications (Q indicator and FMS DEC status page)
Load sharing/torque match - increase Q of low side to match Np no more than 3% above reference
Transient droop comp - compensates, uses collective position indicator
History counter - sends signals to history counter
Hot start preventer - tells ODV to shut off @ 900 degrees Ng<60 Np<50

Question 2

DEC/EDECU maintains constant power turbine speed of

Answer 2

100% (NG)

Question 3

What does TGT limiting limit at

Answer 3

879 +/- 9 - 10 min limit
903 +/- 10 - 2.5 min limit

Question 4

Load sharing keeps both engines matched within

Answer 4

5% torque

Question 5

Overspeed protection kicks at

Answer 5

120% +/- 1% Np

Question 6

Torque matching

Answer 6

-Increases power on lower Q engine to keep Qs approximatly equal
-System will not allow high engine to reduce power to match
-If engine fails highside, good engine should only attempt to increase Q until NP is 3% above reference

Question 7

When does TGT limiting not work

Answer 7

Engine start, compressor stall, lockout

Question 8

Define LOCKOUT

Answer 8

Manual control of engine RPM while bypassing DEC/EDECU TGT limiting

Question 9

How can you override Hot start prevention for an engine start?

Answer 9

By holding either ENG OVSP TEST A or B buttons with the engine being started during the start sequence

Question 10

Is overspeed protection disabled in lockout

Answer 10

No

Question 11

Parameters to bypass 10 minute TGT limit

Answer 11

to go beyond 879 degrees;

DEC - One engine below 50% Q

EDECU -
- Np drops below 96
-Greater than 3% difference between Np and Np reference
-Greater than 5% per second drop to, or below Np reference

Question 12

What can be seen in AC with both a DEC and an EDECU

Answer 12

Torque splits in a “contingency situation”

Question 13

Can you push from idle to fly with rotor brake engaged?

Answer 13

No. There is a rotor brake interlock tab that should prevent this

Question 14

How does the load demand system work

Answer 14

DEC and HMU respond to collective signals

Question 15

Load sharing keeps engines within

Answer 15

5% torque

Question 16

What mechanically links the NG and the accessory gear box?

Answer 16

The power take off assembly

Question 17

What is T2

Answer 17

Inlet air temperature
-used by the HMU to compensate for air temp changes
-Used in NG limiting

Question 18

How is TGT measured?

Answer 18

7 probes on the thermocouple assembly
Probes measure between NG and NP
(silver pipes wrapped on aft end of engine)

Question 19

What are the 4 main modules of the engine

Answer 19

Hot
Cold
Power turbine
Accessory

Question 20

Describe the engine compressor

Answer 20

A 6 stage air pump that continuously pressurizes the combustion chamber, provides bleed air
5 stage axial, 1 stage centrifugal

Question 21

Describe the order of guide veins and compressor stages in order of flow

Answer 21

Air is drawn in through the variable stage 1&2 veins, through 5 axial fixed compressor stators, then through the centrifugal stage

Question 22

What changes the angle of variable stage veins

Answer 22

HMU via a crankshaft assembly

Question 23

When will engine anti-ice activate, even though the switch is off?

Answer 23

88 to 92% NG

Question 24

When can inlet anti ice not be provided?

Answer 24

Torque settings below 10% Q

Question 25

Which of our chip detectors have fuzz burn?

Answer 25

Transmission. Engine chip detectors do not (smaller wire)

Question 26

What are DCUs?

Answer 26

Data concentrator units
-Takes engine, powertrain inputs, and caution/advisory inputs, sends to MFDs
-EICAS compares outputs to generate miscompares

Question 27

What can happen with a DCU fail?

Answer 27

EICAS loses all its shit and goes full reversionary
CHIP IBIT FAIL caution may appear

Question 28

What part of the fire detection system is not tested with positions 1 or 2?

Answer 28

The photo cells
(It does check all detectors POS 1 and deck mounted only in POS 2. Lets find the difference between photo cells and detectors)

Question 29

Failure to see inlet anti ice appear at 4C and below. Can you still fly?

Answer 29

Do not fly in known icing conditions.

Question 30

Oil impending bypass button. Below what temperature should it not pop at all?

Answer 30

Below 38C. Thermal lockout is supposed to keep the button from popping. We should verify if we see a bypass during a cold runup that button has not popped postflight.

Question 31

During engine start, when do engine ignitor exciters fire sparks? Why does it matter?

Answer 31

Until starter dropout
OR
Until ignition key is turned to OFF position.
(Ignitors will not fire if starter is motored with key off)

-Shows why we dont turn key on after engaging starter (hot start)
-Shows why we should turn the key off if starter hangs and doesnt want to disengage with PCL pull down

Question 32

When using an air source other than APU to start an engine, what should you expect?

Answer 32

Expect a hung starter, especially If NG is near low end for cross bleed start (Near 90% NG) or if PSIG for pneumatic start is near low end (40 PSIG)

Near minimum required pressure will be enough to start the engine, but not enough to drive the starter fast enough itself to trigger the starter speed switch, which disengaged the starter.

Question 33

What is the DECs TGT offset (bias)
Is the bias always present?

Answer 33

-112 degrees

When the DEC is not being powered (AC?) am unbiased TGT indication is displayed.

Question 34

If you are going to motor an engine without starting it, what should you do?

Answer 34

Make certain the engine ignition key is OFF

(Think engine flush)

To prevent hot start, never turn on key after starter is engaged.

Question 35

Where does lockout begin? (need to answer still, ask MTP)

Answer 35

Is it a microswitch just past fly?
Half way?
Or do you have to contact the lockout stop?

Question 36

Which is the only non self sealing fuel line?

Answer 36

The APU fuel line

Question 37

How do you use/interpret the Fuel indicating system test button?
(Fuel IND TEST on upper console)

Answer 37

When pressed, the system sends a false empty signal to each tank. Each tank SHOULD read as empty when using the test button

If either tank doesnt read empty when pressing the button, there is a problem.