Originally Posted by
c1223
I was on an A321 the other day where the PTU seemed to make a lot of noise (i.e. the "dogs barking") for about 2 minutes after the gear was bought up. Is that normal? I've only ever heard it when the engines have been turned off on the ground.
The PTU runs when there is a pressure differential between the Green and Yellow System Hydraulics. It runs automatically and provides pressure support when the system is being used by its main heavy users such as the gear and flaps etc. You hear it on the ground because it is quieter, if you were in a NEO they are quieter and it may have been just that.
Last edited by Waterhorse; Mar 10, 2023 at 12:42 am