pax2908
11th Sep 2012, 19:08
Hello, is it normal (common?) to have the PTU operate briefly (~5-10 seconds) during approach (possibly following LG extension) ?
Reimers
12th Sep 2012, 08:24
Yes, it is a normal occurence.
There is so much demand on the green system during extension that the requirements for PTU start of operation are met. Green ENG 1 pump does not have enough capacity to hold the Green system pressure above 2500 psi during gear extension/retraction, so briefly, the PTU will kick in. Should the yellow system not operate, the gear cycle will just take a bit longer to complete.