Does anyone know the USA STC number for
converting a Pawnee from 235 to 250 Hp?

Thanks,

RO

SA1432GL
https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSTC.nsf/0/709179BA4C8E102586256EDD005FC19F?OpenDocument

and SA1456GL
https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSTC.nsf/0/72102702835FE14685256CC10082113F?OpenDocument

On Sunday, July 11, 2021 at 3:51:01 PM UTC-4, youngbl...@gmail.com wrote:
> On Saturday, July 10, 2021 at 9:58:45 PM UTC-4, mrop...@gmail.com wrote:
> > Does anyone know the USA STC number for
> > converting a Pawnee from 235 to 250 Hp?
> >
> > Thanks,
> >
> > RO
> Are you referencing the straight exhaust conversion?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Our 235 Pawnee engine is running strong, but has ~2100
hours on it in a non-commercial application. So, something will
have to be done in the not too distant future. We'd like to
know what the options are beyond just overhauling what we
currently have. We are also running a Hoffman 4 bladed prop
(which keeps the neighbors who are noise conscious happy),
so any power upgrades would have to take that into account.
We have also been offered a very low time IO 540 for a great
price, but don't know something like that can be a player or
not, so like I said, we'd like to know what options are "out there"
so that we can make an informed decision.

RO

Our club purchased a Pawnee in 2015 that had a 250 hp conversion with a Hoffman 4 blade prop.
The STC that we have is actually a 2 step process. 1st STC SE 1433GL will "convert" an 0-540 B2B5 into an 0-540-A1D5 (basically increases the compression ratio). 2nd STC SA1456GL allows you to put this converted engine on a Pawnee. Shortly after we purchased the airplane the 4 bladed prop was damaged (loose prop bolts). We then put the 2 blade on and per the owner of the STC we had to use the heavier 1A200FA prop. Our other Pawnee has the standard 235 HP engine with the lighter tooth pick prop 1P235AFA. The 235 hp Pawnee out climbs the 250 HP STC prop when towing. Both airplanes have the straight exhaust system. You would have to check with Hoffman regarding using your current prop on an increased HP application.
As far as 2100 hours .....if you are operating under part 91, you can keep running that engine....but I understand the uneasiness with a high time engine. Lastly the 0-540 that is for sale cheap....check the suffix of the engine. Not all 0-540s are the same. It should be a B2B5 to match the TCDS.. Good luck and if you have any questions I'd be happy to help.

On Sunday, July 11, 2021 at 3:51:37 PM UTC-5, mrop...@gmail.com wrote:
> On Sunday, July 11, 2021 at 3:51:01 PM UTC-4, youngbl...@gmail.com wrote:
> > On Saturday, July 10, 2021 at 9:58:45 PM UTC-4, mrop...@gmail.com wrote:
> > > Does anyone know the USA STC number for
> > > converting a Pawnee from 235 to 250 Hp?
> > >
> > > Thanks,
> > >
> > > RO
> > Are you referencing the straight exhaust conversion?
> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> Our 235 Pawnee engine is running strong, but has ~2100
> hours on it in a non-commercial application. So, something will
> have to be done in the not too distant future. We'd like to
> know what the options are beyond just overhauling what we
> currently have. We are also running a Hoffman 4 bladed prop
> (which keeps the neighbors who are noise conscious happy),
> so any power upgrades would have to take that into account.
> We have also been offered a very low time IO 540 for a great
> price, but don't know something like that can be a player or
> not, so like I said, we'd like to know what options are "out there"
> so that we can make an informed decision.
>
> RO

On Sunday, July 11, 2021 at 10:37:37 PM UTC-4, needa...@gmail.com wrote:
> Our club purchased a Pawnee in 2015 that had a 250 hp conversion with a Hoffman 4 blade prop.
> The STC that we have is actually a 2 step process. 1st STC SE 1433GL will "convert" an 0-540 B2B5 into an 0-540-A1D5 (basically increases the compression ratio). 2nd STC SA1456GL allows you to put this converted engine on a Pawnee. Shortly after we purchased the airplane the 4 bladed prop was damaged (loose prop bolts). We then put the 2 blade on and per the owner of the STC we had to use the heavier 1A200FA prop. Our other Pawnee has the standard 235 HP engine with the lighter tooth pick prop 1P235AFA. The 235 hp Pawnee out climbs the 250 HP STC prop when towing. Both airplanes have the straight exhaust system. You would have to check with Hoffman regarding using your current prop on an increased HP application.
> As far as 2100 hours .....if you are operating under part 91, you can keep running that engine....but I understand the uneasiness with a high time engine. Lastly the 0-540 that is for sale cheap....check the suffix of the engine. Not all 0-540s are the same. It should be a B2B5 to match the TCDS. Good luck and if you have any questions I'd be happy to help.

> > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Many thanks for the info and offer. It looks like we have some
homework to do now.

RO

On Monday, July 12, 2021 at 8:06:48 AM UTC-4, mrop...@gmail.com wrote:
> On Sunday, July 11, 2021 at 10:37:37 PM UTC-4, needa...@gmail.com wrote:
> > Our club purchased a Pawnee in 2015 that had a 250 hp conversion with a Hoffman 4 blade prop.
> > The STC that we have is actually a 2 step process. 1st STC SE 1433GL will "convert" an 0-540 B2B5 into an 0-540-A1D5 (basically increases the compression ratio). 2nd STC SA1456GL allows you to put this converted engine on a Pawnee. Shortly after we purchased the airplane the 4 bladed prop was damaged (loose prop bolts). We then put the 2 blade on and per the owner of the STC we had to use the heavier 1A200FA prop. Our other Pawnee has the standard 235 HP engine with the lighter tooth pick prop 1P235AFA. The 235 hp Pawnee out climbs the 250 HP STC prop when towing. Both airplanes have the straight exhaust system. You would have to check with Hoffman regarding using your current prop on an increased HP application.
> > As far as 2100 hours .....if you are operating under part 91, you can keep running that engine....but I understand the uneasiness with a high time engine. Lastly the 0-540 that is for sale cheap....check the suffix of the engine. Not all 0-540s are the same. It should be a B2B5 to match the TCDS.. Good luck and if you have any questions I'd be happy to help.
>
> > > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> Many thanks for the info and offer. It looks like we have some
> homework to do now.
>
> RO

I’d be leery of that IO-540, since Pawnees aren’t set up for a fuel injected engine (that’s the “I” in the prefix). Would require 337 paperwork approval for additional mods if not covered in the STCs.

Larry Ruggiero