THE LNDG GEAR COLLAPSED DURING A TOUCH AND GO.

Narrative

THE LNDG GEAR WAS EXTENDED AND CHKED ON THE DOWNWIND LEG OF THE TFC PATTERN FOR THE RWY. I FLEW AN EXTENDED-LENGTH DOWNWIND LEG TO ALLOW SAFE SPACING BEHIND THE CESSNA 172 IN THE PATTERN AHEAD OF US. I RE-CHKED THE LNDG GEAR STATUS ON THE FINAL LEG. WE MADE A SUCCESSFUL NORMAL FULL-FLAP LNDG WITH A GENTLE TOUCHDOWN OCCURRING NEAR THE APCH END (THE 'NUMBERS'). WE PROCEEDED TO ROLL ALONG ON THE RWY WITH NO APPARENT PROB. THE INSTRUCTOR REQUESTED THAT I IMMEDIATELY TKOF. I MOVED THE THROTTLE TO APPLY FULL PWR FOR TKOF. EITHER DURING OR SHORTLY AFTER THIS PROCESS; THE NOSE APPEARED TO DROP AND I WAS UNABLE TO MAINTAIN CTL OF THE ACFT. (THE INSTRUCTOR RPTED THAT HE ATTEMPTED TO TAKE CTL OF THE ACFT BUT WAS ALSO UNABLE TO MAINTAIN POSITIVE DIRECTIONAL CTL). THE ACFT THEN SKIDDED ALONG THE RWY EVENTUALLY COMING TO REST ALONG THE L SIDE OF THE RWY WITH THE LNDG GEAR MOSTLY RETRACTED. THE L WING WAS LOCATED OVER THE GRASS WHILE THE R WING WAS LOCATED OVER THE ASPHALT. THERE WERE SIGNS OF SMOKE AROUND THE EXTERIOR OF THE COCKPIT. I SHUT OFF THE FUEL VALVE; TURNED OFF THE BATTERY; TURNED OFF THE IGNITION; OPENED THE CANOPY; AND EXITED THE ACFT. THERE WERE NO APPARENT WITNESSES TO THE ACTUAL LNDG. THERE WERE NO APPARENT INJURIES SUSTAINED BY THE ACFT PAX. THERE WERE NO OTHER NON-CREW PERSONS IN THE VICINITY OF THE ACFT DURING THE LNDG. THE ACFT DAMAGED SOME OF THE RWY EDGE LIGHTING DURING THE SKID. NO OTHER PROPERTY WAS DAMAGED. THERE ARE 2 IMMEDIATE APPARENT EXPLANATIONS FOR THIS MISHAP: MECHANICAL FAILURE OR PLT ERROR. THE ACFT MECHANICAL SYS HAVE NOT BEEN ANALYZED AT THIS TIME. NOTHING UNUSUAL WAS DETECTED DURING THE PREFLT INSPECTION. (HOWEVER; THE INSTRUCTOR RPTED SEEING A PUFF OF SMOKE NEAR THE FRONT OF THE ACFT AT THE APPROX TIME OF THE LOSS OF CTL). THE MOST OBVIOUS PLT ERROR CAUSING THIS IS THE PREMATURE PLACEMENT OF THE LNDG GEAR HANDLE IN THE UP POS. I HAVE NO RECOLLECTION OF TOUCHING THE LNDG GEAR DURING THIS PROC. IF I HAD MOVED THE GEAR HANDLE TO THE UP POS; THE GEAR SHOULD NOT HAVE RETRACTED IF THE WT ON THE MAIN GEAR WAS SUFFICIENT. ALSO; THE GEAR WARNING HORN SHOULD HAVE SOUNDED. (THE GEAR WARNING HORN WAS FUNCTIONING PROPERLY DURING THE IN-AIR MANEUVERS PERFORMED EARLIER). THE GEAR WARNING HORN DEFINITELY WAS NOT HEARD BY THE INSTRUCTOR OR MYSELF DURING THE LNDG/TKOF ROLL. ANOTHER POSSIBLE EXPLANATION IS THE INADVERTENT ACTIVATION OF THE EMER GEAR RETRACT SWITCH. I DO NOT HAVE ANY RECOLLECTION OF ACTIVATING THIS. THE INTENTIONAL ACTIVATION OF THIS REQUIRES A VERY DELIBERATE ACTION TO BREAK OPEN THE SAFETY-WIRED GUARD WHICH COVERS THE ACTIVATION TOGGLE SWITCH. (IT IS POSSIBLE THAT THERE WAS A MALFUNCTION IN THIS SYS). CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE NAVY HAS CONDUCTED AN ACCIDENT INVESTIGATION REGARDING THIS INCIDENT AND HAS NOT FOUND THE CAUSE. THE RPT STATED 'POSSIBLE PLT ERROR OR POSSIBLE MECHANICAL FAILURE.' THE ACFT ANTENNAS; FLAPS; EXHAUST AND PROP WERE ALL DAMAGED. THE RPTR WAS NOT HELD TO BLAME AS HE WAS NOT THE PIC. W29 IS AN UNCTLED ARPT.