I have to disagree with the canadian with the perfect Amphib record. On the older EDO floats eg 4580" or the streatched 4930" and you can include the Edo amphibd for thr Otter. The main gear is held in the retracted position by hydraulic pressure ONLY. There are no mechanical catches. If the pressure in the system is released the main gear will drop. We had a lot of trouble when operating in salt water with the salt eating into the steel hydraulic lines causing holes and therefore leaks to develop. I know of several cases where the steel cable which retracts the front wheels has failed causing the pilot to land on the water with one front gear locked in the down position.
The older systems did not have a back up hydraulic system. if for any reason a break occured between the pump and the landing occurs the pump simply empties the oil [ normally onto the pilot's feet ] . I have personally had this happen in an Otter and ended up with the nose gear up and secure but the main wheels dangling halfway between full up and full down. After much deliberation we landed very gingerly on the water. We pulled up very quickly but safely with no damage. a quick pipe replacement and some new oil and away we went.
The whiplines have a dual pump and tank system and the gear has mechanical locks so the Edo problems do not occur.
The only method to avoid gear stuff ups is to look out the window. Have a set of mirrors the enables the crew to visually check all wheels. Add the visual check to your check list and never ever fail to use your written check list. This will keep you from getting wet and having to fill out lots of paperwork.
