Quote from me:
"Have never understood quite why the A320 PTU is so audible in the cabin."
And from fantom:
"Easy: drop both gear doors and you can look straight through the fuselage in mid section. It's empty except for the Hyd system. When the PTU barks up, it is heard just about everywhere."
Remember it well. The PTU is on the keel, IIRC.
You've exposed the sloppiness of my question. What I was trying to say was: why do we not hear similar noises in the cabin on other types of similar size? Presumably they have a PTU/RMP. Is it positioning, mounting, or simply a noisier PTU?
Chris