SMA ON TRAINING FLT HAS LNDG GEAR PROBS.

Narrative

WE WERE IN A 1960 CESSNA 310D MODEL. I WAS GIVING FLT INSTRUCTION TO THE OWNER. WE DEPARTED 5W9 ENRTE TO DPL FOR FUEL AND TRAINING. WE HAD DONE SEVERAL MANEUVERS WHICH CALL FOR THE GEAR TO COME UP AND DOWN. ONE TIME WE DID NOT GET A GREEN LIGHT AND WE CHKED THE MIRROR AND CONFIRMED THE GEAR WAS NOT FULLY EXTENDED. WE WENT THROUGH THE EMER CHKLIST; BUT THE HAND CRANK APPEARED TO BE STRIPPED. WE WERE ABLE TO PULL THE GEAR UP; BUT NOT DOWN. I TRIED PUTTING HVY POSITIVE AND NEGATIVE G'S ON THE ACFT; BUT NOTHING WORKED. I DECIDED TO GO TO ISO. WE NOTIFIED THEM OF OUR PROBS AND OUR INTENTIONS. WE TRIED WORKING WITH THE GEAR ANOTHER 30 MIN. WE DID A LOW FLY AND THE CFR CONFIRMED THAT THE MAINS WERE DOWN BUT THE NOSE GEAR WAS NOT FULLY EXTENDED. WE DECIDED TO LAND WITH 2 DOWN SO WENT LINED UP WITH THE RWY AND ON SHORT FINAL I OPENED THE DOOR; TURNED OFF THE FUEL SHUTOFF VALVE; AND ALL THE ELECTRICAL EQUIP AND THE MAGNETOS. WE TOUCHED ON THE MAINS; AND HELD OUT TO REDUCE SPD. WE TOUCHED ON THE NOSE OF THE ACFT. THE DAMAGE TO THE ACFT WAS MINOR; AND NO DAMAGE TO THE OCCUPANTS.