I’m talking -300/400:
The LGTU includes a shuttle valve that opens under the mentioned conditions to port Sys B pressurized fluid via the unit to the landing gear “retraction mechanism”. So, fluid actually transfers. During each gear raising attempt about 0.8gal Sys B fluid will be lost (dumped into a reservoir as the gear up valve repositions).
If there is a rupture from the LGTU towards the landing gear, then you will be unable to retract the gear.
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happy landings