The Cessna 310 is an American four-to-six-seat, low-wing, twin-engine monoplane produced by Cessna between 1954 and 1980. It was the second twin-engine aircraft that Cessna put into production; the first was the Cessna T-50. It was used by the U.S. military as the L-27, after 1962, U-3. Over six thousand Cessna 310 and 320 aircraft were produced between 1954 and 1980.
Development The 310 first flew on January 3, 1953, with deliveries starting in late 1954. The sleek modern lines of the new twin were backed up by innovative features such as engine exhaust thrust augmenter tubes and the storage of all fuel in tip tanks in early models. In 1964, the engine exhaust was changed to flow under the wing instead of the augmenter tubes, which were considered to be noisy.
Typical of Cessna model naming conventions, a letter was added after the model number to identify changes to the original design over the years. The first significant upgrade to the 310 series was the 310C in 1959, which introduced more powerful Continental IO-470-D engines. In 1960 the 310D featured swept-back vertical tail surfaces. An extra cabin window was added with the 310F.
The turbocharged 320 Skyknight was developed from the 310F. Equipped with TSIO-470-B engines and featuring an extra cabin window on each side, it was in production between 1961 and 1969 (the 320E was named the Executive Skyknight), when it was replaced by the similar Turbo 310.
The 310G was certified in 1961Type Certificate 3A10, p. 11. and introduced the canted wingtip fuel tanks found on the majority of the Cessna twin-engine product line, marketed as "stabila-tip" tanks by Cessna, because they were meant to aid stability in flight. A single side window replaced the rear two windows on the 310K (certified in late 1965), with optional three-blade propellers being introduced as well.Type Certificate 3A10, p. 19. Subsequent developments included the 310Q and turbocharged T310Q with a redesigned rear cabin featuring a skylight window, and the final 310R and T310R, identifiable by a lengthened nose containing a baggage compartment. Production ended in 1980.
Over the years there were several modifications to the 310 to improve performance. Aircraft engineer Jack Riley produced two variants, The Riley Rocket 310 and the Riley Turbostream 310. Riley replaced the standard Continental engines with Lycoming TIO-540 engines. These turbocharged intercooled engines were installed with three-blade Hartzell propellers in a counter-rotating configuration to further increase performance and single-engine safety. At gross weight the aircraft had a weight to power ratio of per horsepower. This resulted in a cruising speed of at and a rate of climb.
Operational history
Commercial applications The Cessna 310 was a common charter aircraft for the many air taxi firms that sprang up in the general aviation boom that followed World War II. The advantages of the Cessna 310 over its contemporaries, such as the Piper PA-23, were its speed, operating costs and aftermarket modifications, such as the Robertson STOL kits that made it popular worldwide for its bush flying characteristics. It could use short runways, while at the same time carrying a large useful load of . or more, at speeds that were high for a twin engine piston aircraft.
Military applications In 1957, the United States Air Force (USAF) selected the Cessna 310 for service as a light utility aircraft for transport and administrative support. The USAF purchased 160 unmodified 310A aircraft with the designation L-27A and unofficially nicknamed Blue Canoe,Krivinyi, Nikolaus: World Military Aviation, page 148. Arco Publishing Co., 1977. later changed to U-3A in 1962. An additional 36 upgraded 310 designated L-27B (later U-3B) were delivered in 1960–61; these aircraft were essentially military 310Fs and as such equipped with the more powerful engines and can be identified by their extra cabin windows, longer nose and swept vertical fin. A USAF study after one year of operational service found the U-3A had direct operating costs of less than $12 an hour.Phillips, Edward H:Wings of Cessna Model 120 to the Citation III, Flying Books, 1986. The U-3 saw active service in a support role when the USAF deployed aircraft to South Vietnam during the Vietnam War, where they were used on courier flights between air bases.Harvey 1966, p. 69.Harvey 1966, p. 80. Some USAF aircraft were later transferred to the U.S. Army and U.S. Navy and the type continued in United States military service into the mid-1970s.
Notable private flights On December 19, 1992, Cuban defector Major Orestes Lorenzo Pérez returned to Cuba in a 1961 Cessna 310 to retrieve his wife and two sons. Flying without lights, at low speed and very low altitude to avoid Cuban radar, Pérez picked up his family by landing on the coastal highway of Varadero beach, Matanzas Province, east of Havana and managed a successful safe return to Marathon, Florida.Google News, Top Cuban Pilot Defects to US The Deseret News, 21 March 1991, retrieved 5 January 2012Cuban Pilot Who Defected Flies Back for Family The New York Times, 21 December 1992, retrieved 29 June 2017
Variants
310 Initial production variant, powered by two Continental O-470-B or O-470-M engines with carburetors, with maximum takeoff weight of ;Type Certificate 3A10, pp. 1–2. in production for 1955-1957 model years, 547 built. 310A Military version of the 310 for the United States Air Force, designated L-27A and later U-3A; with Continental O-470-M engines and maximum takeoff weight of ;Type Certificate 3A10, pp. 2–3. 161 built.Type Certificate 3A10, p. 3. 310B Model produced in 1958, with new instrument panel,Simpson 1995, p. 126 O-470-M engines and maximum takeoff weight of ;Type Certificate 3A10, p. 4. 225 built.Type Certificate 3A10, p. 5. 310C Model produced in 1959, with Continental IO-470-D fuel-injected engines and maximum takeoff weight increased to ;Type Certificate 3A10, pp. 5–6. and minor changes; 260 built.Type Certificate 3A10, p. 6. Unit cost $59,950 in 1959 310D First model with swept vertical tail,Cessna 310 thru 310D (1955–1960) Maintenance Manual, Section 6-10-00. Retrieved June 24, 2017 other minor detail changes; 268 built for 1960 model year. 310E Military version of the 310F, designated the L-27B and later U-3B; with maximum takeoff weight of ;Type Certificate 3A10, p. 8. 36 built.Type Certificate 3A10, p. 9. 310F Model produced in 1961, with extra cabin window each side, pointed nose and other minor changes; maximum takeoff weight of ; 155 built.Type Certificate 3A10, p. 10. 310G First model with canted slimline tip tanks and optional six-seat cabin, with maximum takeoff weight increased to and detail changes, 156 built in 1962. 310H Model produced in 1963 with maximum takeoff weight increased to Type Certificate 3A10, p. 13. and enlarged cabin interior. 148 built. E310H Version of 310H with the maximum takeoff weight of the 310G;Type Certificate 3A10, p. 14. combined total of 148 310H and E310H built. 310I First model with baggage compartments in rear of engine nacelles, Continental IO-470-U engines and minor detail changes; 200 built in 1964. 310J Model produced in 1965 with minor detailed changes and maximum takeoff weight of .Type Certificate 3A10, p. 15. 310J-1 Version of 310J type-certified in the Utility Category; with maximum takeoff weight increased to ; seating limited to four people instead of the 310J's six; and reduced baggage weight limit.Type Certificate 3A10, pp. 16–18. E310J Version of 310J with maximum takeoff weight reduced to ;Type Certificate 3A10, p. 18. combined total of 200 310J, 310J-1 and E310J built.Type Certificate 3A10, pp. 17–19. 310K First model with optional three-blade propellers and long 'vista view' side windows; also increased maximum takeoff weight of with IO-470-V or IO-470-VO engines;Type Certificate 3A10, pp. 19–20. 245 built in 1966. 310L First model with increased fuel capacity via fuel tanks inside wings and optional fuel tanks in engine nacelles,Type Certificate 3A10, p. 21. also single-piece windshield, redesigned landing gear, and minor changes;Taylor 1967, p. 238. 207 built in 1967. 310M Revised designation for the 310E. 310N Model produced in 1968, with revised instrument panel and provision for optional cargo door and fuel;Taylor 1968, p. 254. 198 built.
Model produced in 1969, with Continental IO-470-VO engines,Type Certificate 3A10, p. 23. ventral fin and a shorter nose gear leg.Taylor 1969, p. 301.
Version of 310P with turbocharged Continental TSIO-520-B or TSIO-520-BB engines producing and maximum takeoff weight of ;Type Certificate 3A10, pp. 24–25. combined total of 240 310P and T310P built.
Last short-nose model, introduced in 1970, with maximum takeoff weight increased to Type Certificate 3A10, p. 27. and detailed changes, from the 401st aircraft fitted with a bulged rear cabin roof with rear view window. T310Q Version of 310Q with turbocharged Continental TSIO-520-B or TSIO-520-BB engines and maximum takeoff weight increased to ;Type Certificate 3A10, pp. 28–29. combined total of 871 310Q and T310Q built.
Last production model, introduced in the 1975 model year, with Continental IO-520-M or IO-520-MB engines; three-blade propellers as standard; lengthened nose containing a baggage compartment; and maximum takeoff weight.Type Certificate 3A10, pp. 29–31. T310R Version of 310R with turbocharged Continental TSIO-520-B or TSIO-520-BB engines;Type Certificate 3A10, p. 31. combined total of 1,332 310R and T310R built. 310S Original designation for the Cessna 320. 320 Skyknight Enlarged version of the 310F with six seats, larger cabin and two turbocharged engines; 110 built. 320A Skyknight First model with canted fuel tanks and minor changes; 47 built. 320B Skyknight First model with nacelle baggage lockers, minor changes; 62 built. 320C Skyknight Model with a longer cabin, optional seventh seat and minor changes; 73 built. 320D Executive Skyknight Model with reshaped rear windows and TSIO-520-B engines; 130 built. 320E Executive Skyknight Model with pointed nose, single piece windshield, modified landing gear, increased takeoff weight and minor changes; 110 built. 320F Executive Skyknight Model with minor changes compared to 320E; 45 built. L-27A United States military designation for the 310A, later changed to U-3A. L-27B United States military designation for the 310E/310M, later changed to U-3B. U-3A L-27A redesignated in 1963. U-3B L-27B redesignated in 1963. Colemill Executive 600 Conversion of models 310F to 310Q, replacing the engines with Lycoming TIO-540-J2BDs driving four-bladed propellers.Mitchell 1994, p. 305.
Riley 65 Conversion offered for models 310 to 310G, replacing the engines with two 240-260 hp (179–194 kW) Continental O-470Ds or -470Ms.Taylor 1966, p. 314. Riley Super 310 Conversion of Cessna 310/320 by fitting two 310 hp (231 kW) Continental TSIO-520J or 520N engines.Taylor 1982, pp. 453–454. Riley Turbostream Conversion of Cessna 310 by fitting two 350 hp Lycoming engines. Riley Rocket Conversion of Cessna 310 by fitting two 290 hp (216 kW) Lycoming IO-540-A1A5 engines and more fuel capacity. Riley Turbo-Rocket Riley Rocket with each engine fitted with two Riley-manufactured turbochargers. Cruise speed increased from to .Taylor 1967, p. 340.
Operators
Civil
The aircraft is popular with air charter companies and small feeder airlines, and is operated by private individuals and companies.
Hinterland Aviation
Military operators Countries known to have operated the U-3/310 include.
Argentina Argentine Air Force — Cessna 310 and 320 models Bolivia Colombia Colombian Air ForceForster World Air Power Journal Autumn 1997, p. 136. Republic of the Congo France French Air and Space Force — 12 operatedAndrade 1982, p. 67. Haiti Haiti Air Corps Indonesia Indonesian Air ForceAndrade 1982, p. 106. Indonesian Army Aviation Iran Madagascar Air Force of Madagascar — One 310RAndrade 1982, p. 151.