'67 airplane would be the engine driven hydraulic pump. If you had answered that it took a while, like many minutes or hours, I would have suggested an internal leak in an actuator. But if they start to sag when the power comes off, that sounds to me like a sequencing valve is in the wrong position, and I am not smart enough about the gear system to suggest where. It would be similar to the part of the system that makes the gear doors pump open when the master is off, and closed when the master is on.
I hope one of the smarter folks on the site can offer you more help.
Kevin
|