View Full Version : 777, C1/C2 Hyd pumps.

29th Jan 2010, 09:22

During acceptance in Seattle we had to check the output for C1/C2 ELEC pumps. The manual says 2900 to 3200 PSI.
But I've checked the maintenance manual and it shows 2800 to 3200 PSI.
Did someone challenged our friends at KBFI already about this?

29th Jan 2010, 13:31
I am assuming that the first manual is the Boeing Aircraft Acceptance Manual and would have harder values for you the customer.

The Maintenance Manual values would be the extreme limits, so when 2800psi is OK but one psi below and your pump is now requiring replacement. Not so good if you just had the aircraft delivered.
I would have thought that the upper value was too high to accept as well.

Might be totally wrong but going to double check with our B777 acceptance and AMM.


29th Jan 2010, 14:41
I think Tinwacker has the answer, our AMM still states the following

SUBTASK 29-11-02-210-003
(7) Make sure the HYDRAULIC SYSTEM PRESS C indication, on the EICAS maintenance page, is
2800 to 3200 psi.

However for the Engine driven pump it states

SUBTASK 29-11-05-210-005-002
(4) Make sure the L (R) HYDRAULIC SYSTEM PRESS indication on the EICAS maintenance display
is 2900 to 3200 psi.

Perhaps this is where the confusion comes from also?

7th Feb 2010, 15:08
Your right about the AMM content and that's what I ve found too. After discussion with one expert we came to the conclusion that the value into the acceptance manual is higher because brand new pump / system is supposed to produce at least the 2900. Maintenance will call for replacement/check if pressure goes below 2800. Hence the difference in both documents.