This amphibian was designed by the Italian Nardi firm (hence FN =
Fratelli Nardi) and was intended to have folding wings, but this
configuration was never adopted. The three-seat F.N. 333
prototype first flew from Aeroporto Forlanini in Milan on December 4,
1952. It was fitted with rounded tail fins and an 145 hp Continental
engine, while the prototype of the enlarged four-seat F.N. 333S with
enlarged squared tail fins and a 225 hp Continental C-125 engine,
first flew on December 8, 1954.
Two more prototypes were constructed, the first of those, I-EUST,
flew on October 14, 1956, the model getting its CAA Type Certificate
on December 15, 1958. One (probably the first prototype) of the F.N.
333s built by Nardi had fixed wing floats, while in all other
aircraft they were retractable in the wing tips. One aircraft,
piloted by Guiseppi Alesini set up 6 international records.
Unfortunately, at that time Nardi was not able to establish a
production line, plans for manufacturing by Fiat did not materialise.
Finally production was undertaken by SIAI-Marchetti in Sesto Calende,
the aircraft receiving the name Riviera and a 250 hp Continental
engine. First production model flew in February 1962 and 23 (c/n 001
to 012 and 101 to 111) were built untill production ended 1966, the
most of the aircraft were sold in USA, where it was marketed as the