So sorry to hear about your gear extension issues with 489C. As you are aware (but others may not be), your aircraft has a different gear indicating system than other M200s. 489C has a transit lights, where stock aircraft have UP (red) and DOWN (green) lights.
The Gear system of the M200 is quite simple: an engine driven hydraulic pump with a backup hand pump, and Uplock release cables attached to the gear handle, with backup Uplock release cables that may be manually pulled if the others fail.
Here are a few thoughts to help walk through an analysis of a landing gear anomaly:
If there is hydraulic pressure indicated on the pressure gage, then pumping the hand pump won’t provide any benefit as the engine driven pump will provide more pressure than the pilot can achieve with the hand pump (especially while flying). If an Uplock cable attached to the gear handle breaks (or malfunctions), then raising the gear handle (assuming hydraulic pressure is indicated) to get the weight of the gear off the Uplock, pulling the Uplock manual cables and lowering the gear (with the manual cables held in the fully pulled position), should allow the gear to drop. Air loads will not hold the mains Up (even without hydraulic pressure), but may slow the nose from dropping. A quick wing rock will lock the mains and a quick pull up should extend the nose.
If there is zero hydraulic pressure indicated on the gage when the gear handle is lifted to energize the hydraulic system, one of 3 issues may be at play; (1) bad gage, (2) the engine driven hydraulic pump has failed, (3) there is a leak in the hydraulic system and the fluid has bled out (100 psi when in bypass will bleed the system empty quickly). You can verify a leak vs engine driven pump failure by hand pumping; no pressure = no fluid, pressure = pump failure. If no pressure (seen on the gage or felt while pumping) is gained when hand pumping, then there is probably no fluid in the system. Good news is that lowering the gear handle will release the Uplocks and allow the landing gear to fall into the DOWN position. If pressure is gained by pumping, then pump the hand pump to pressurize the system. If time permits, you may pump the hand pump with the gear handle in the UP position to raise the gear off of the Uplocks prior to moving to the DOWN position, but it shouldn’t be required if the Uplock rollers are properly lubricated. Hydraulic pressure will bleed down quickly if using the hand pump, so use of flaps will require occasional pumping to keep them down (if fluid is available and pressure can be built up). Easiest to accomplish a no flap landing to a paved runway. Be cognizant that without hydraulic pressure, small bumps may cause the gear to lose over center and collapse. Be gentle and minimize gear side loads with hydraulic emergencies.
Ray, I’m curious as to what caused the main gear to get stuck in the UP position… Did a gear door cable catch on the scissor link, or did the tire catch on the sheet metal with the retracted strut?
An easy way to get some air in a collapsed start is to jack up the aircraft and add air to the strut using the strut pump (if Nitrogen isn’t readily available). By jacking the aircraft you are not trying to lift the plane’s weight while charging the strut. It won’t get you to the 700+ psi required, but it should get it off the fully bottomed position. Final pressure will be determined by length of strut extension desired. New seals will be required if it bled down, but your mechanic should be able to rebuild the strut as it is straight forward. Also, you may want to replace the bushings while the strut is off the plane.
Practicing gear emergencies during annual maintenance landing gear swings while the aircraft is on jacks is a good opportunity to witness gear transits and learn hand pumping techniques. You may need to “backhand” the pump lever to keep from scraping your knuckles on the circuit breakers. Been there, done that, have the scars…