Cessna 185 Conversion

 

Davis Aviation offers engine upgrades available for all Cessna 185 aircraft. Our STC removes the IO-470 F or IO-520 D and replaces it with the 300 HP continuous IO-550 D. This powerful engine is installed with your choice of various propeller options. The early model 185s may require some additional changes not needed on the later model aircraft.

Formerly known worldwide as the “Bonaire 550”, this conversion provides phenomenal performance with shorter takeoff roll, increased rate of climb, and faster cruise speeds. Basically, we picked up where Cessna left off when manufacturing stopped in the late 1980’s. Most of the older propellers have become obsolete and require replacement. The higher horsepower engine installed with the newer design propeller change, makes a cost effective difference for your Cessna 185 at minimal expense.

While any of the propeller options do well with an IO-550 engine, the Hartzell 80 inch Top Prop, 82 inch Paddle Blade and McCauley Black Mac (offered at 80, 82, 84, 86 or 88 inch) models are designed more for takeoff and climb performance, where the Hartzell Scimitar (78 inch) is designed for cruise. The Hartzell 3 blade Super Scimitar (80 or 82 inch) is kind of the best of both worlds with the 82 inch diameter for takeoff and climb and swept blade for cruise. The larger diameter (above 82 inch diameter) McCauley will provide the best take off performance but will not provide as much change in cruise with the added diameter. The new 86 inch Harrzell 8429 Voyager model will be available with the 550 engine soon. This propeller will provide comparable performance to the larger diameter Black Mac model but with the swept design to keep cruise speed up and noise to a minimum. The composite MT propeller is an 82 inch propeller and will perform similar to the other models. The real advantage of the MT propeller is the weight decrease. This propeller is about 26 lbs lighter than the other models. This will help improve your useful load. For those that like the 2 blade model, we can offer the 86 inch McCauley 228 propeller. This propeller is restricted to wheels only as manufacturer testing was not done for the float option.

Note that the Davis Aviation 550 STC shows most of the propeller models on the engine and propeller STC. However, other models may be installed with a 2nd prop only STC that calls out our IO-550 STC. The proper STC documents will be provided with our kit package.

If you have upgraded your propeller already, generally the model you have installed is compatible with our IO-550 STC. Give us the model number of the existing propeller upgrade and we can determine compatibility.

IO-550 Conversion Improvements

  • 400 inch lbs more torque over the IO-520 engine/15% More Horsepower at Cruise.
  • 40 more Horsepower with the IO-470 F installation
  • Quieter operation: the noise level at 2700 RPM is greatly reduced with the 80 or 82 inch propellers.
  • 10-20 MPH additional cruise speed improvement depending on propeller choice.
  • 10%-20% better rate of climb at gross Continuous 300HP without limitations.
  • Short field take-off 10%-20% less at full gross weight.
  • Cost difference is normally offset by the added value to the plane.

 

What Our Clients Are Saying about our Cessna 185 Conversion

 

The Davis conversion to the Continental 550 with the Black Mac 88″ prop was the the best investment I have and could have made to my 1976 Cessna 185. The plane is now turbine smooth, the performance is night and day difference.  On floats especially, it is almost instantly on the step upon full application of power, where as the old engine would chew up a significant amount of water trying to achieve the same results. I am able to operate in smaller lakes with a larger safety margin than before. In cruise with the power pulled back to 22.5″ squared I see the same fuel burn I did with my Continental 520 with the same indicated airspeed on floats. I could not be happier. Donna was great to work with, she made all the coordination through my mechanic shop and the installation / shipping to Alaska was painless.

 

Joe Head, Cessna 185 Owner