Engines

Question 1

EEC Overview

Answer 1

Dual Channel
Regulates engine performance
Monitors Thrust Levers and A/P
To set thrust

EEC have two modes of operations:
Normal and Alternate
Normal protects provides ground start protection: - Hot start (rapid rise in EGT)
- Wet start (no rise in EGT in 15s)
- Engine stalls and EGT exceedances of 725°

Should a failure occur the EEC reverts to Soft Alternate mode and Master Caution ENG illuminates.
Soft Alternate mode uses the last sensed environmental condition to calculate engine limit values.

The Hard Alternate mode is engaged when the thrust levers are retarded to idle or by pushing the EEC switches.

Question 2

Soft Alternate

Answer 2

Required signals not available
On and ALT displayed in switch
Uses last sensed flight conditions
As conditions change exceedances are possible:
Climb or descent ,Temperature, etc

ALT MODES LACK SOME SAFEGUARDS SO ADVANCING THRUST LEVERS FULL FWD CAN LEAD TO OVERBOOST EGT LIMITS

Question 3

EEC Hard Alternate

Answer 3

Selected by pilot after a Soft Alternate
Indicated by ALTN with ON out of view
Assures thrust at least equal to what Normal would provide

ALT MODES LACK SOME SAFEGUARDS SO ADVANCING THRUST LEVERS FULL FWD CAN LEAD TO OVERBOOST EGT LIMITS

Question 4

EEC Normal Mode

Answer 4

ON in view ALT blank
Calculates N1 thrust settings

Uses actual flight conditions and bleed air demand

EEC drives power to achieve thrust rating selected
27,26,24 or 22k per engine

Question 5

EEC Structural Limit Protection

Answer 5

N1 and N2 over speed
EEC provides protection in both Normal and ALT modes

EGT Limit-no protection in any mode, pilots must monitor

Question 6

EEC Idle Power Modes

Answer 6

Ground Idle
Lowest thrust idle setting

FLT Min Idle
Idle selected for most phases of Flight

APPROACH IDLE
Higher thrust N1 and N2 than FLT min
Engine acceleration for GA and or
Provide addl bleed air production
(Anti ice on)

Selected by EEC in flt if:
Flaps in LDG config OR
ENG Anti ice on

Maintained until after touchdown

Question 7

If the EEC looses flap or anti ice signals due to a fault:

Answer 7

Approach idle activates at 15,000 ft MSL

Question 8

Engine Panel
REVERSER LIGHTS ON
(A-T-I-S)

Answer 8

A- Auto restore circuit activated

T- one or more TR sleeves not in commanded state

I- Isolation valve or TR control valve not in commanded position

S- Sync: Failure in sync shaft lock circuit

Question 9

ENGINE CONTROL LIGHT

Answer 9

Engine control system not dispatchable due to system fault

Light operates only on ground with engine operating and:
Airspeed below 80kt prior to TO
Or
Approx 30 seconds after touchdown