@PM: the gear is hydraulically lowered and latched by an hydraulic power pack which receives its pressure not from engine driven pumps, but one electrically motored pump.
No electrics means emergency extension and no lights. You need to pump quite a while (no freefall and hydr. pressure required to lock) to get the thing locked (IME) and if donīt get it locked or cant verify it locked (e.g. no lights) then the book tells you to pump as long as there is resistance that you canīt overpower and LEAVE the pump handle at the top of the stroke. IF you stow it, you`d take the pressure off the system, pressure that had been supplied to the extend side of the actuators.
No having pumped long enough and having stowed the pump handle COULD cause the gear to retract. When all 3 gear retract that would be a plausible thing IMO, but of course there is always the possibility of say a failure in the valve or so...
In preparation to pump the gear down one has to put the gear handle down and has to pull the control CB. That way the pressure from the handpump can enter a small pilot hole and shuttle the valve to the extend side. Failure to do so could lead to a valve that electrically 'creeps' back (with the remaining low voltage, its just a magnetic coil...) and releases the pressure also. (pure speculation on my part)
One thing in the electrical system of the 200 is critical and thats the current limiters and their checking... an item Iīve seen often omitted and I was told by the chief technician of the shop we had our KingAir maintained, that they - relatively - often find them blown. Now, if both GENs are working, you wonīt see anything amiss, but if there is e.g. voltage drops or the like on the faulty side, then you donīt have the battery to dampen these out, which in turn can cause further problems to e.g. the GCU.
I had one GEN shadding its parts and in the event sending voltage peaks into the system throwing out the other side as well. We were on a sharpish ILS approach in a snow storm going into an Ukrainian Airport - nothing I recommend for recreation...
On a side not, B200s have 250 Amp Gens or optional 300 Amp ones.
Last edited by His dudeness; 31st July 2012 at 23:32.