SMA SEL FLOAT PLANE SANK DURING TAXI FROM THE DOCK DUE TO WATER IN THE FLOATS.

Narrative

THE ACFT INVOLVED WAS A CESSNA 185 AMPHIBIOUS FLOAT PLANE. I WAS THE PLT OF THE ACFT WHEN ON TAXI OUT THE ACFT SUBMERGED INTO LAKE NORMAN; A LAKE APPROX 30 MI N OF CHARLOTTE; NC. PRIOR TO THIS EVENT THE ACFT WAS BROUGHT DOWN TO LAKE NORMAN BY ME ON A FERRY PERMIT BECAUSE THE ACFT WAS OUT OF ANNUAL INSPECTION; AND WAS TO BE BROUGHT TO FORT LAUDERDALE FOR ITS OWNER. UPON ARR TO THE LAKE THE FLOAT PLANE WAS DOCKED AT MY RESIDENCE IN WHICH IT WAS THEN I DECIDED TO CHK THE FLOATS FOR WATER. ONLY TO FIND OUT LESS THAN A CUPFUL CAME OUT OF EACH PUMP OUT AND REMEMBERING THAT NONE CAME OUT OF THE FORWARD PUMP OUT (PRETTY MUCH AIR). BECAUSE OF THE SMALL AMOUNT FOUND IN THE OTHER PUMP OUTS I RECOGNIZED THE LACK OF WATER FOUND IN THE FORWARD COMPARTMENT WAS A NON ISSUE. ONLY LATER DURING TAXI OUT TO DISCOVER DIFFERENTLY WHEN A SMALL AMOUNT OF PWR WAS APPLIED AND THE FLOATS BURIED AND PULLED THE ACFT UNDER. THE CAUSE COULD BE FAULTY PUMP OUT LINES ON ICE DUE TO COLD WINTER OP. THEREFORE I FEEL THAT THE FLOAT DESIGNER SHOULD GIVE THE PLT A BUBBLE GAUGE OR INDICATOR SO THAT IF THIS IS THE PROB; THE PLT WOULD NOT ATTEMPT MOVEMENT OF ACFT UNTIL THE PROB WAS SOLVED.