Wanted clever PA32 engineer's thoughts - Gear extention problem on Piper Lance

On 18-Jul-2003, "Richard Kelly" wrote:

This gave the impression that the gear will not
free fall into the down and locked position - It will. However what was
missing from the statement is that if I prevent the gear from falling ie
hold the nose leg back (simulating too fast an airspeed) and then someone
resets the circuit breaker the pump will happilly power the leg into
position.


Oh! Well, given that new info I would guess that the most likely culprit is
the shuttle valve in the power pack. This is the valve that directs the
pump's pressure to the retraction or extension sides of the hydraulic
circuit. The high pressure with the gear retracted may be somehow
preventing the valve from moving from the "retract" to the "extend"
position. However, when you reduce the pressure (with the emergency
extension valve) the shuttle valve is then freed up to move to the proper
position.

Actually, given all your symptoms the problem could be with the pressure
switch (external to the power pack) being set too high, so that the
hydraulic pressure with the gear retracted is excessive, which might be what
keeps the shuttle valve from moving properly. I am sure that Piper
specifies a correct pressure range in its service manual, and this can be
tested by a qualified A&P (err... "engineer").

All of the above are just the musings of an amatuer, of course, but
hopefully it might help.

-Elliott Drucker