The Cessna 340 is a pressurized business aircraft with a twin piston engine that was manufactured by Cessna. Appearing externally the same, a less successful unpressurized version of the Cessna 340 is The Cessna 335. This six seat aircraft was designed as a cabin-class development of the successful Cessna 310, with four passenger seats, an aisle and an airstair door. Being one of the first turbocharged piston twins to house intercoolers installed, the Cessna was ultimately proven right in their concept of incorporating turbo-intercooling into general aviation aircraft. Now all turbocharged piston engine aircraft come from the factory with intercoolers installed as standard equipment. The manufacturers have finally given credit to the importance of intercooling, with American Aviation to thank being one of the innovative engineering centers.

Development of the 340 began in 1969. However, the loss of the prototype early in 1970 causes a minor set back in the development program and the production deliveries did not begin until early 1971. The outcome was an aircraft which borrowed heavily from other Cessna twins of the time including the wings from the 414 and the 310′s undercarriage and a similar tail unit. New design features of the aircraft included a pressurization system with a differential of 0.29bars (4.2psi) that kept the cabin’s internal altitude at 8000ft while the aircraft was at 20,000ft, an all new fail safe fuselage and an integral airstair door.

First production 340s were powered by two 210kW (285hp) turbocharged Continental TSIO-520-K engines. Soon after, these were replaced on the improved 340A, which was first introduced in 1976. Two 230kW (310hp) TSIO-520-NBs powered the 340A. Reduced diameter props and a slight increase in weights are just some improvements incorporated in the 340A. Cessna also offered in optional 340A II and 340A III forms with various levels of IFR avionics fitted.

The Cessna 335 differed by its lighter weight thus lowering cost of its development than of the 340. Available from 1979, this unpressurised aircraft had 225kW (300hp) TSIO-520-EB engines. Only 64 335s were built even though Cessna claimed it as the lowest priced cabin class business twin on the market. Production was terminated in 1980.

General characteristics

Crew 1
Passengers 5
Propulsion 2 Piston Engines
Engine Model Continental TSIO-520-NB
Engine Power (each) 231 kW 310 hp
max. Cruise Speed 787 km/h 425 kts
  489 mph
max. Speed (vne) 837 km/h 452 kts
  520 mph
Service Ceiling 9.083 m 29.800 ft
Rate of climb 503 m/min 1650 ft/min
Range 774 km 418 NM
481 mi.
Empty Weight 1.780 kg 3.924 lbs
max. Takeoff Weight 2.720 kg 5.997 lbs
Wing Span 11,62 m 38,1 ft
Wing Area 17,1 m² 184 ft²
Length 10,46 m 34,3 ft
Height 3,84 m 12,6 ft
First Flight 1970
Production Status out of production
Total Production 1351
ICAO Code C335 / C340
FAA TCDS 3A25
Data for (Version) Cessna 340A
Variants 335, 340, 340A

Sources:
http://www.airliners.net/aircraft-data/stats.main?id=151
http://www.flugzeuginfo.net/acdata_php/acdata_c340_en.php
http://www.pilotfriend.com/aircraft%20performance/Cessna/C340%20C335.htm
http://www.americanaviationinc.com/cessna.html
http://www.worldlingo.com/ma/enwiki/en/Cessna_340
http://en.wikipedia.org/wiki/Cessna_340