Franklin O-335

The Franklin 6A4 (US military designation O-335) was a series of air-cooled aircraft engines of flat-6 configuration. These engines were commonly vertically-mounted and used to power many early helicopters in the US. They were closely related to the 2A4 and 4A4 2- and 4-cylinder engines. In various subtypes, the 6A4 remained in continuous production from 1945 to the time Franklin's US operations ceased in 1975, with versions continuing in Polish production into the 1990s.

Applications

• Aero-Flight Streak
• Aeronca Sedan
• Bartlett Zephyr
• Bell 47
• Bellanca Cruisair
• Goodyear Duck
• H-23 Raven
• Hiller 360
• Seibel S-4
• Sikorsky S-52
• Stinson Voyager
• Taylorcraft 15
• Temco TE-1B
• YT-35 Buckaroo

Specifications (6A4-165)

References

• Gunston, Bill. (1986) World Encyclopedia of Aero Engines. Patrick Stephens: Wellingborough. p.57
• Erickson, Jack. Horizontally-Opposed Piston Aero Engines
• US Department of Transportation Federal Aviation Administration Type Certificate Data Sheet E-238 Revision 12, December 8, 1994.