Larson Aircraft Sales

  1978 Cessna 310R 
(Colemill IO-550 Bearcat Conversion and Known-Ice)

The Colemill IO-550 Bearcat conversion gives the ultimate normally aspirated performance for the Cessna 310R airframe.  The IO-550 is very conservatively rated at 300 hp, and most that really know the engine agree that it is comparable to the 300 hp IO-520 at 325+ hp.

The IO-550 is also approved for continuous operation at the 300 hp rating, and also approved for lean of peak operations.

The IO-550 Conversion gives near turbo performance without the expense of the turbo system. This plane at high RPM (2500) will produce over 200 KTAS at 7500 feet.

The following quote is from an article titled Colemill Foxstar Baron: A Better Baron? by Peter A. Bedell, AOPA magazine Sept 2000:

"The IO-520 is a good engine, but it was not built under the minimum-horsepower concept like the newer IO-550. Under this rule, the IO-550 must produce at least 300 hp plus 10 percent and minus zero percent. The 520 can be within plus or minus 10 percent of 285 hp. That means that with all of its accessories dragging it down, an IO-550 will deliver the full 300 hp (and probably more) for a net horsepower increase better than the 30 hp total listed on the specifications sheet. Not surprisingly, owners who've made the conversion see cruise speeds of their airplanes increase by 10 knots or so. In addition there are proportional gains in takeoff and climb performance."

There is also a good article showing the merits of the IO-550 engine which was written on the Atlantic Aero IO-550 conversion for the Cessna 210.

Back to AEST-SALES.COM Home Page

Cessna 310R



        • 7370 Hours Total Time Since New
        • Logbook, Airframe, NTSB/Incident Reports and Form 337 review indicate No Major Damage History.
        • Recent Extensive Annual done Jan 2010 with Cessna 300/400 Specialist
        • No Corrosion Issues - Midwest Plane to 2008, Arizona 2008-2010 and Hangared Since New
        • 1800 lb. + Useful Load with VG's / Gross Weight Increase
        • SK414-8E (Sidebrace Kit) done 1991

        Optional Equipment:

        • Three-Blade Propellers
        • Strobe Lights
        • Known Ice (Boots tight, good condition with some patches)
        • 163 Gal Fuel Cap
        • Reiff Engine Preheat System
        • GAMI Injectors



        • Garmin GMA-340 Audio Panel with Marker Beacon
        • Garmin GNS-530 WAAS GPS  (Nav / Com / Map IFR Certified)
        • King KCS-55A Slaved HSI
        • King KI-256 Flight Director
        • King KY-196 Digital Comm
        • King KNS-80 RNAV / Nav #2 with Glideslope
        • King KI-209 Nav Indicator
        • Garmin 330 Digital Transponder #1 with Traffic Information
        • King KT-76C Digital Transponder #2
        • Bendix-King RDR-2000 Vertical Profiling Radar, Heading Stabilized (A $24,000 radar system uninstalled, the best radar you will find in a 310!)
        • Norton Radome
        • WX-950 Stormscope
        • S-Tec 65 Autopilot with Altitude Preselect, Altitude Hold, Approach Coupling, Optional Yaw Damper, and GPS Steering ($45k+ today to install)
        • Terra Radar Altimeter
        • Shadin Digital Fuel Management System
        • Insight GEMINI 1200 Graphic Engine Monitor
        • Co-pilot's Electric attitude indicator

Engines & Propellers
    • Continental IO-550 (300 rated HP, 1700 Hour Recommended TBO)
    • 845 Hours Since Factory Remanufactured Engine (Left)
    • 570 Since Prop Overhaul (Left)
    • 1570 Hours Since Factory Remanufactured Engine (Right)
    • 0 Since Prop Overhaul (Right)

Paint & Interior

Paint was done in the early 1990's, base with with burgundy and grey accents. Paint is starting to show its age but the plane is still very presentable and a little detailing will go a long way. I would rate the paint a 6/10 as it sits - with some polishing and limited touchup the plane would be a solid 7/10.

Interior was done in the early 1990's in pale beige leather and is in fair to good condition.  Some significant wear showing on the front seats and armrests, but no rips, tears or abuse.  The rear four seats show little use, and are in exellent condition.

Back to Larson Aircraft Sales Home Page

Larson Aircraft Sales
Phone: 303-503-8356
Fax: 303-413-9728
Physical Location:
Longmont - Vance Brand Airport (KLMO)
229 Airport Rd.  (Hangar H-1B)
Longmont, CO 80503
Mailing Address:
Larson Aircraft
PO Box 19641
Boulder, CO 80308

© Larson Aircraft Sales (All rights reserved)