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 North Star.
four-seat prototypes, and production model
Max T/O Wt:
One 250 hp Continental IO-470-P six-cylinder air-cooled engine
34 ft 1.5 in (10.40 m)
24 ft 3.5 in (7.40 m)
10 ft 7 in (3.23 m)
163 sq.ft (15.14 sq.m)
2,304 lb (1,045 kg)
3,274 lb (1,485 kg)
177 mph (285 km/h) at sea level
1,220 ft (372 m)/min at sea level
18,504 ft (5,640 m)
559 mls (900 km)