Dependable aircraft maintenance since 1966 – Family owned and operated since 1977


STC Services - C182

FAA Approved Supplemental Type Certificates (STC)

Better than new plane performance, at less than a new plane price.

John Jewell Aircraft, Inc offers engine and propeller upgrades, along with a 3-blade prop-only option for the C182 Legacy series aircraft.

Our 252hp – O470U upgrade for all legacy models through 1986 "Better than new plane performance, without Better than new plane price" is accomplished through:

  • Modified accessories in the C182-252
    • STC modified carburetor.
    • Larger diameter balance tube (induction cross-over tube).
  • RPM increased to 2625
    • Prop Blade angle change
    • McCauley Prop Governor change
  • Requires engine, prop, accessories change for models through 1976
    • Requires ONLY accessories change for 1977-1986 models
    • Two prop options: C204 (McCauley 2-blade) & 7691 (Hartzell 3-blade) NOTE: 3-blade option requires additional STC engine mount change

The JJA C182-252 STC does not require any external cowling modifications. With the exception of the 3-blade prop option, aircraft does not differ from its pre-modified appearance.

The JJA C182 STC power plant used is not considered "highly modified" engines and therefore O470U engine retains full core value for future overhauls and exchanges. The STC documentation/data plates provide the information required continuing the 252hp performance into future overhauls of your STC'd C182.

This conversion allows upgrade to an O470U (2000 hour TBO) along with a 252hp @ 2625 rpm conversion. Two prop options are available: McCauley 2-blade 204 or Hartzell 7691 3-blade. NOTE: 1977 and newer C182 models are factory equipped with O470U and McCauley C204 prop, therefore existing equipment may be used.

Benefits of the 252hp STC

  • 2000 TBO (2200 TBO on engine serial numbers 1006000 and greater)
  • Available 252hp @ 2625 rpm
  • Maximum horsepower achieved without expense of fuel injection modification
  • Up to 400 fpm increase in rate of climb
  • 5-8 kts increase in cruise, at gross weight
  • Average fuel consumption remains unchanged &ndash to one gph increase
  • Most economical cost-to-value C182 Performance Upgrade for Legacy C182's
  • Decrease in operation costs over original 230hp engine
  • True airspeeds in excess of 170mph!

Frequently Asked Questions

FAQ: What is difference between my existing O470-R or S and the O47OU?
The O470-R/S models were designed to only produce 230 horsepower. The O470U is a carbureted version of the IO470 model that was designed to produce up to 260 horsepower as an injected model. The JJA 252 STC allows the O470U to produce 252hp at 2625 RPM without the expense of injection modification.
FAQ: Can I convert my existing O470-R or S to an O470U?
In most cases no. Some O470S models can be converted by crankcase modification, using different crankshaft, counterweights and cylinders. However, most times, converting existing engines becomes cost prohibitive.
FAQ: Is there a core difference when exchanging my O470-R or S with the Factory for an O470U?
No. The O470-R, -S, and –U all have the same core value.
FAQ: Am I required to purchase an O470U from the Factory to install this STC?
No. However, an “unlike core” exchange with the Factory in most cases is the easiest and most economical.
FAQ: Can I reuse my existing 2-blade prop from the O470-R or S?
No. One of the differences between the O470R/S models and the O470U is the number of counterweights. The 2-blade prop that is used with the O470-R/S mates with a 2-counterweight engine. The O470U is a 4-countereweight system and the prop must also match accordingly.
FAQ: Am I required to purchase a brand new C204 prop from the Factory?
No. Our price for brand a new prop is usually most economical over other sources for brand new props. Our props will be supplied with the blade angles factory-set for the STC limitations. However, you and your installation facility are welcome to use a C204 prop from the vendor of choice. The prop blade angles required for C182-252 installation will not be the same as used on a stock O470U. Inform the prop vendor of this in order for the proper blade angles to be included at “build-up”.
FAQ: Since I will have to purchase a new prop when changing from an O470-R or S, would it not be best to go ahead and go 3-bladed?
Not necessarily. Some applications do require extremely short take-offs. However, JJA has found that the over-all best value and performance is to remain 2-blade propeller when remaining carbureted. When increasing the horsepower, along with the 3-blade propeller, the engine mount cradle must be changed. The 3-blade prop will give better climb; however, in cruise the 2-blade prop will be more efficient with equal performance.
FAQ: I already have Factory-equipped O470U and C204 prop. What labor is required?
We estimate approximately 10 hours for STC installation when engine is not being exchanged. New STC requires exchange of carburetor, prop governor, balance tube (proper fitting for clearance on some serial numbers) and exchange of mechanical tach and R&R of prop for blade angle change
FAQ: Are there additional services that are required?
When aircraft is equipped with digital tachs, the mechanical tach is optional. However, the digital tach may require changes for the RPM limitation changes. Refer to the digital equipment’s manufacturer.

For existing C204 prop installations, the prop blade angles will require change for the change in RPM’s. This can be accomplished at prop overhaul at no additional charge. However, prop overhaul is not necessarily required. The nature of the C204 hub does not allow for blade angle change to be accomplished externally. A prop shop usually can perform this for a nominal fee. Consult log books and installation facility.

Cessna Flyer Association - More Mods, More Modern: Even More Good Things for the 182
Modifications for the Cessna 182.