Per my Avcon drawing, you need the following:

.68 hole in firewall
1000-11 grommet
1000-12 shield
AN931-9-10 Grommet
PK76XZ-8-6 Screw (2 required)
NAS446-4 Nut (2 Required)

These parts are basically the same as the shield I posted, with nuts, screws, and grommets.

Yesterday the STC for tailwheel conversion and 180hp + CSU arrived for my C172.

It took about 60 days to receive the package, Bob told me this, and I was fine with it as I am in no rush.

Both STCs include parts lists, tech drawings and instructions for installation, and of course the STC cover sheet with my aircraft serial number on it.

The installation instructions for both are fairly vague, but no more vague than other STC installs I've done. It's more of a guide than a detailed set of instructions.

The parts list is not all that helpful. Some Of The part numbers are specific to the STC'd parts which are unavailable anyway and need to be supplemented with alternatives such as gearlegs, engine mount and tailwheel bracket. These will likely require a separate approval depending on your country etc..

The scale drawings are great, and in my opinion you don't really need much else to do the conversion paperwork wise.

Hello all. I am new to the group. I have some questions about the Avcon conversion also. We have a 1965 Cessna 172F that was converted to 0-360-A1A with Hartzel constant speed prop using the STC sa807ce back in the mid 70's by the CAP. None of the paperwork besides the actual STC is in the records. Mainly we have a couple questions to the group to see if anyone could help. There is an AUX facet brand fuel pump mounted on the R/H lower side of the firewall and the part number is long gone. The pump has power to it but is not functioning any longer..actually hasn't functioned for quite some time. Question 1- I assume this pump is on the A/C because of the original STC...is this true? Question 2- If question 1 is true then would anyone be able to tell me the part number of the pump? Question 3- When is the pump required to function according to the operating instructions for the STC..during takeoff only?? We appreciate any assistance in the matter Thank you very much.

1. Yes, the pump is required. It is a backup to the engine driven pump mounted on your engine.

2. Sorry, I don’t have a part number.

3. The pump is required to be energized for takeoff and landing. If the :mechanical pump were to fail in one of those evolutions, gravity feed will not be sufficient to provide full power to the engine. This is because of the diameter of the fuel line from the fuel selector to the engine. Fred Dyen was able to field approve removal of both pumps, by installation of a larger diameter line there. Good luck getting that done today.

Williams should be able to get you a part number.

MTV

The STC for the fixed pitch 0-360 conversion lists 476-087 on the parts list, which does cross reference with a 4 PSI facet pump.

MTV, jcadwell thank you for the info! I did send an email to Williams..I will see if he sends back and hopefully does not say I will have to purchase the paperwork to see the P/N. I am thinking that there shouldn't be a difference between the engine set up with the constant speed versus fixed pitch in regards to the Pump part number. If anyone else has any thoughts or info please send our way. Thank you!!

jcadwell wrote:The STC for the fixed pitch 0-360 conversion lists 476-087 on the parts list, which does cross reference with a 4 PSI facet pump.

I've been told that the CS AVCON O-360 conversion can climb with a steeper deck angle than a fixed pitch equipped aircraft with the same engine. Same person said the high deck angle could unport the fuel if 1/4 tank or less. Since it's been several years since that conversation took place, take it for what it's worth... a conversation starter here.

The wing tanks installed in the 170A, 170B, early 172's, and 175's have a single outlet installed just aft of the fuel gauge location in the tank. That is the reason for the "No Takeoff" range, marked in red on the fuel gauges, do to the possibility of the outlet un-porting at high deck angles. I own a 170B with a 180 Lyc and a 80 inch Hartzell constant speed prop. The limited STC documentation, including installation drawings I obtained from the Cessna 170 Assoc, that I have does not include a limitation that the electrical pump is required to be on for takeoff or landing, though that is probably the safest option. I do not use the electrical pump for takeoff or landing unless a maximum angle of climb is required for obstacle clearance. My best guess was that the installation is patterned after the installation of the 180 Lyc in a Cherokee 180 in which case if the engine driven pump were to fail there would be no gravity fuel flow.

Tim

Hello I have a 59 175 S/N: 55787 and it has the Bob Williams STC SA424CE. When I bought the plane there were no drawings with the STC paper work. My lord engine mount need to be replaced and I don’t believe the correct ones are installed (J-7401-8). I have tried to contact Bob Williams and had no luck. Would anyone be able to help out with some drawings or any help with getting the right part number that will be greatly appreciated.

Lugi wrote:Hello I have a 59 175 S/N: 55787 and it has the Bob Williams STC SA424CE. When I bought the plane there were no drawings with the STC paper work. My lord engine mount need to be replaced and I don’t believe the correct ones are installed (J-7401-8). I have tried to contact Bob Williams and had no luck. Would anyone be able to help out with some drawings or any help with getting the right part number that will be greatly appreciated.

I have a 58 with the conversion. I’ll look, but don’t think I have drawings either.

MTV

Thanks MTV, if you could next time you’re by your plane can you take a look at the rubber engine mounts that go between the engine and the metal engine mount itself. There will be a number on them. I currently have J7401-8s installed on mine but I am not sure if they are the correct ones. Thanks

I have the drawings, obtained them from the Williams after many months of contacts about 6 years ago.

" J7402-5 Lord Mount Assy 4 Reqd
AN7 35A Bolt 4 Reqd
AN960-716 Washer 4 Reqd
Install 4 places. Torque nuts to 450-500 in/lbs"

Lugi, can you send me a PM with your email address? I can send you some pictures.

Hello Brady! What year model 172 do you operate? Curious if yours has the same conversion with same parts..thanks!

Good day,

I have a Cessna 175 A here in Botswana fitted with an STC 777CE from Bob Williams. We dont have the installation instruction nor supporting documents. The STC was done back in 1982 and installation instruction seems to have been misplaced. I have tried reaching out to Bob Williams for the papers on [email protected]. He responded once.

Can someone help me with the STC 777 CE documents.

I have a 172 with a Doyn conversion who owns their stc? Mine is SA420CE