GEAR COLLAPSE UPON LNDG. NOSE GEAR IS EXTENDED; MAIN GEAR NOT LOCKED IN EXTENDED POS.

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PROB WAS THAT THE MAIN LNDG GEAR COLLAPSED ON LNDG. NOSE GEAR WAS DOWN AND LOCKED IN POS. PROB NOTICED ON LNDG WHEN GRATING NOISE OCCURRED. PLANE WAS MANEUVERED TO SIDE OF RWY AT THIS TIME. CHAIN OF EVENTS: PLT TAKING DELIVERY ON NEW ACFT THAT HAD RECENTLY BEEN REPAINTED. 6 HR FLT MADE THAT DAY AS A PAX IN PVT ACFT WITH 2 FRIENDS. FRIENDS DECIDED TO TRAVEL TO ANOTHER DEST AND REPEATEDLY MADE ENCOURAGEMENTS TO FOLLOW. RELUCTANTLY MADE DECISION TO FOLLOW THEM ON AN APPROX 45 MIN FLT. NOT VERY FAMILIAR WITH DEP ARPT; LCL AREA OR DEST ARPT. DEPARTED BARTOW AND ON CLB EXPERIENCED DIFFICULTY WITH GPS WHICH WAS RADIO THAT WAS PLANNED TO BE UTILIZED ON FLT. SINCE DID NOT REALLY DESIRE TO MAKE THE FLT; MADE A DECISION TO MAKE A TURN AND RETURN TO BARTOW. DID NOT KNOW HOW I WAS GOING TO CONTACT FRIENDS AND TELL THEM OF THIS FINAL DECISION. FLAPS AND GEAR LEVERS WERE DEPRESSED ON DOWNWIND AND OBSERVATION MADE THAT GEAR WERE EXTENDED. AGAIN; ON TURN TO FINAL; GEAR WERE OBSERVED WITH NOTHING NOTED. ON TOUCHDOWN ACFT LANDED SMOOTHLY. THOUGHT THAT THIS REALLY WAS A VERY SMOOTH LNDG UNTIL NOISE WAS HEARD AS BOTTOM TOUCHED SURFACE. VERY SURPRISED SINCE FELT STRONGLY THAT GEAR HAD BEEN LOWERED. PLANE WAS EASILY MANEUVERED TO THE SIDE OF THE RWY WITHOUT DIFFICULTY AND UNEVENTFULLY OTHER THAN IT WAS ON THE HULL. NO CORRECTIVE ACTION WAS TAKEN OTHER THAN TO MANEUVER TO THE SIDE OF THE FIELD SINCE IT WAS TOO LATE TO HAVE MADE ANY OTHER ACTION. HUMAN FACTORS: A LONG TRIP HAD BEEN MADE THAT DAY. EXCITEMENT SURROUNDING A NEW ACFT. NOT OVERLY FAMILIAR WITH ARPT AND AREA. DID NOT REALLY DESIRE TO MAKE A FLT TO ANOTHER DEST BUT GAVE INTO PLEADINGS FROM FRIENDS. OVER 200 HRS TIME IN A LAKE ACFT; HOWEVER; THIS WAS FIRST SOLO PIC FLT IN THIS MODEL ACFT WHICH IS SIMILAR BUT HAS DIFFERENCES. PROB WITH RADIO CAUSED DISTR. HAD PROB WITH FUEL PUMP NOISE WHICH CAUSED DISTR. OBSERVED GEAR TO BE IN POS BUT APPARENTLY THEY WERE NOT LOCKED; SEATS IN THIS ACFT POSITIONED HIGHER NOT ALLOWING QUITE THE SAME RANGE OF VIEW OF THE MAIN GEAR AS MY OTHER LAKE ACFT. THIS; I FEEL; CAUSED A PERCEPTION PROB FOR ME AND CAUSED ME NOT TO TAKE ANY ACTION. I AM ASSUMING THAT THE GEAR WERE NEVER LOCKED INTO POS PRIOR TO LNDG. I DO NOT RECALL LOOKING AT HYD PRESSURE GAUGE WHILE INFLT BUT 500 LBS WAS INDICATED AFTER TOUCHDOWN. UPON CYCLING THE GEAR LATER WE WERE NOT ABLE TO GET THE GEAR LIGHT TO MALFUNCTION; SO I ASSUME IT WAS NOT OBSERVED. SINCE A MALFUNCTION COULD NOT BE REPEATED; THE PROB I MUST ASSUME WAS DUE TO HUMAN PERFORMANCE. THE LACK OF CORRECT PERFORMANCE WAS DUE TO A NUMBER OF EVENTS AND DISTRS WHICH IN THEMSELVES WAS NOT SIGNIFICANT BUT TOGETHER WAS ENOUGH TO CAUSE THE NON OBSERVANCE OF A CRITICAL CHK THAT OF THE LNDG GEAR LIGHT AND HYD PRESSURE. SINCE THE EVENT; I HAVE TALKED WITH A NUMBER OF OTHER LAKE ACFT OWNERS AND HAVE GIVEN THIS CONSIDERABLE THOUGHT. SEVERAL OTHER PLTS HAVE RELATED THAT THEY HAVE EITHER HAD A PROB OR A CLOSE CALL WITH SIMILAR CIRCUMSTANCES. MOST AMPHIBIAN PLTS ARE TRAINED TO TAKE GREAT CARE IN WHETHER THE GEAR ARE UP OR DOWN AND IF POSSIBLE MAKE AN OBSERVATION. I MAKE A VERBAL CALL AS TO GEAR UP OR DOWN AND WHETHER THE LNDG IS ON THE LAND OR WATER AND LOOK AT THE GEAR. IT HAS BEEN MY EXPERIENCE AND OTHERS THAT DUE TO WATER CONDITIONS THAT GEAR LIGHT MALFUNCTIONS OCCUR WITH SOME FREQ. I DO NOT KNOW IF ANYTHING CAN HELP THIS BUT IT DOES CAUSE ONE TO NOT ALWAYS PLACE FAITH ON THIS LIGHT. THE OTHER ISSUE IS THE HYD PUMP AND PRESSURE IN THE SYS. I BELIEVE THAT THE PUMP IN MY ACFT MUST NOT HAVE BEEN ON OR NOT OPERATING PROPERLY. PRESSURE WAS IN THE SYS BUT IT WAS NOT SUFFICIENT TO LOCK THE GEAR IN POS. I MADE INCORRECT GEAR POS OBSERVATIONS AND DID NOT NOTICE LOW HYD PRESSURE. I AM NOT AN ACFT DESIGNER OR VERY KNOWLEDGEABLE ABOUT HYD SYS BUT WHY IS THE HYD PUMP NOT ALWAYS WIRES TO BE FUNCTIONAL WHEN THE ENG IS OPERATIONAL. THIS WOULD INSURE ADEQUATE PRESSURE AND ELIMINATE ONE POSSIBILITY FOR PLT ERROR IN ALLOWING PRESSURE TO BECOME INADEQUATE FOR FULL OP OF GEAR; FLAPS; AND TRIM IN THIS ACFT. ANOTHER SOLUTION WOULD BE THE DEVELOPMENT OF A WARNING DEVICE SUCH AS A HORN OR LIGHT THAT WOULD ACTIVATE AT A CERTAIN LOW PRESSURE LEVEL. ALSO; AN OVERRIDE SWITCH COULD BE PLACED THAT WOULD TURN ON THE PUMP AT A CERTAIN LOW PRESSURE IF IT WAS MISTAKENLY TURNED OFF OR NOT TURNED ON. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR CALLED TO DETERMINE WHAT WAS REQUIRED TO KNOW GEAR WAS DOWN AND LOCKED. THE NOSE GEAR WAS DOWN WHICH MEANS THE GEAR LEVER WAS PLACED IN THE DOWN POS. PLT SAW THAT THE MAIN GEAR HAD EXTENDED; BUT HE FAILED TO VERIFY IT WAS LOCKED IN THE DOWN POS. THE HYD GAUGE SHOWED 500 PSI AFTER TOUCHDOWN; IT NORMALLY HAS 1000 PSI WHEN GEAR IS EXTENDED. HE STATES HE KNEW HE PLACED THE GEAR LEVER DOWN; BUT EVIDENTLY FAILED TO CHK PRESSURE AND LOCK INDICATIONS.