ERJ190 elec hydraulic pump2 operation logic
 

On ERJ190, elec hydraulic pump2 has a very special operation logic,
it says :
On ground the elec hydraulic pump 2 will be automatically activated when following condiion occur
1.Eng 1 running and parking brake released
I can understand this no problem.
2.During eng1 start(once N2 reaches 40%) if parking brake has been applied within the last 6 min.
note: the elec hydraulic pump 2 will be automatically turn off after 6 min have elapsed from parking brake application.
Can anyone help me to decode condition 2 ?

Yes :-)

The logic to make ACMP2 run includes the questions

1)Is ENG 1 running and Eng 2 OFF? This is yes if the N2 of Eng 1 is >40% and Eng 2 OFF.

2)Has the parking brake gone from off to on in the last 6 minutes?

3)Is the Parking brake OFF?

IF 1 and (2 or 3) is true the pump will run.

The idea is that the pump runs whenever you taxi with Eng 1 running and eng 2 shutdown, but will continue to run if you stop for a short period (< 6minutes)in the taxi. The keep running logic is to stop the pump cycling on and off during a long que of traffic when you are stop and starting a lot.


Because of how the logic is implemented if the parking brake is off or has been applied in the last 6 minutes the second part of the run logic is true (2 or 3) so when you start Eng 1 first you will then complete the logic part 1 and the pump will run for whatever part of the 6 minutes since the brake was appilied remains.