Gear Trouble

Unbelievable.







The 182RG (R182) should be similar to the 177RG. We have
the R182, and the pump has a pressure switch that shuts off around
1600 psi. There are two relief valves in the system, one that relieves
the electric pump at 1800 psi and the one that relieves the manual
pump at 2200. Both valves and the pressure switch are supposed to get
checked at the 100-hour inspections, as does the gear swing ("Five
fault-free cycles," as Cessna puts it). This requires jacking the
airplane to a ridiculous and scary height, so a lot of mechanics won't
do it.
The gear warning horn has two switches: One in the flap
mechanism and the other on the carb, operated by a cam on the throttle
shaft. The horn will sound if the throttle is reduced below a certain
point or if the flaps are lowered below 23 degrees. The flap switch
will make sure the horn sounds even if the throttle is in all the way.
The green light system is wired to stop the horn when it fires. (Or
you could turn off the master.)
The gear-down light is operated by three microswitches, one
for each leg, wired in series. The yellow gear-up light is wired to
three others. The gear-down switch on the nosegear is actuated by the
downlock mechanism, and so the nosegear must be down and locked for
the circuit to close. The mains don't absolutely have to be locked for
their switches to close, since they're not going anywhere after weight
is on them anyway.
The OP's complaint, as I think about it, is probably due to
the nosegear's switch not closing because the hydraulic cylinder
wasn't pulling hard enough to yank the lock into place. It wasn't
pulling hard enough because it is bypassing fluid internally, making
the system pressure low and keeping the pump running. The hydraulic
systems is supposed to be overhauled every five years to replace the
rubber bits that do this, but guess how many of them are within THAT
limit? There's another R182 on the field here that has had that same
bypassing problem. Fixed, now.
So, as I see it, that OP's nosegear downlock was not locked
(and its switch not closed) until the vibration of the wheel touching
down shook the hydraulics a bit and made the piston seal finally catch
and bring the pressure up, pulling the lock into place. He is SO
lucky, especially considering that he flew the thing home again with
no guarantee that the system would hold pressure to keep that lock
from jumping out. And that's why the Regs require grounding an
airplane when a defect is present.

Dan
There's a squat switch on the nosewheel scissors that prevents
pump operation if the leg is extended.