Chapter 5 - Electronic Engine Control Unit Flashcards
What does the EECU, FMU and other networking sensing devices do in relation to the engine?
They control the engine gas gen and power turbine speeds in response to the load demanded by the rotor system
What does the EECU provide?
Electronic interface between engine sensors and actuators as well as discrete and serial communication interfaces between the engine and the core heilvionics system
What does the EECU and CHS communicate via?
RS422-A link
How do the two EECUs communicate?
Via ARINC 429 data bus
What does the permanent magnet alternator PMA do?
it is driven by the accessory drive train and provides the EECU electrical supply under normal conditions above 50% NG
How is the EECU powered during startup and shut down?
they are energized by 28VDC ess busses 1 for 1 and 2 for 2.
The ess bus is also used for emerg power inn case of PMA failure
What 11 functions does the EECU provide?
Auto engine starting Limit override function OEI training mode OEI counting Cycle counting Failure detection
What time period can the limit override be used for?
Max 20sec
When will the power turbine overspeed protection system shut down an engine?
It will shut down the engine if the NF reaches 118%
What happens when both NF sensors indicate overspeed?
A signal is sentr to close the stop electro-valveas to stop the engine immediately
As well as a ‘#1/2 OVSP’ caution message will display on the CAS (Master caution light turns on)
What happens when 1 overspeed system operates?
The two EECUs cross-talk therefore it inhibits the overspeed function of the other engine
What happens when the EECU detects that an NF sensor has failed?
A ‘#1/1 OVSP DET’ caution appears on cas
What are the 3 levels of maint and data failures?
Level 1 failure (loss of redundancy) Y #1/2 ECU MAINT
Level 2 failure (degraded control) Y #1/2 ECU
Level 3 failure (total failure) Red #1/2 ECU FAIL
What does EPAC stand for and indication?
Engine power assurance check.
The EPAC indicates if the engine power available is within the limits estab by the flight manual
