Air box for Avcon conversions and split cowling

How to keep the Cessna 170 flying and airworthy.

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marathonrunner
Posts: 449
Joined: Mon Dec 13, 2010 3:49 am

Air box for Avcon conversions and split cowling

Post by marathonrunner »

Ok I'm hoping this lets me post my photos. I guess I can only post 5 and I have nine so I will post 5 here and maybe 5 more on another post. When I put my Avcon conversion on in the early 1990's. I knew the orange scat hose for the air on would be an issue. I always see them in poor condition with holes which greatly reduces volumetric efficiency. Not wanting to have hose I made an airbox inlet that attaches to the airbox and it was an easy field approval.

In addition to not having to deal with the hose on cowling installation it also does not shake and crack the nose owl at the air filter. If left unclamped they don't shake it and crack it with the hose but to install the hose you have to remove the airbox and reinstall if you don't use the clamp at the forward end.

I also didn't want a nose bowl that you had to remove the propeller to get to the front of the engine. In the hoots you can see I split mine and have 3 machine screws per side with nutplates. I also got rid of all cowling screws and put in plus flush cam locs.

If the pictures down come through I will have Bruce post them.

Cheers, happy flying and happy 4th
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It's not done till it's overdone
flyboy122
Posts: 324
Joined: Mon Apr 21, 2014 2:30 am

Re: Air box for Avcon conversions and split cowling

Post by flyboy122 »

My Avcon converted 170 came with a split cowl just like yours. I thought that's how they all were?! If not, they certainly should be.

I definitely like your intake mod. The biggest PIA to my current setup is unscrewing the filter box anytime I have to remove the bottom cowl, and trying to re-find the screw holes during installation again. Plus I ended up with a cracked mounting flange last year that was no fun to fix. Yours looks much better!

DEM
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DaveF
Posts: 1516
Joined: Sat Nov 03, 2007 1:44 am

Re: Air box for Avcon conversions and split cowling

Post by DaveF »

My Avcon is as shown on drawing 17002 -- split cowl and induction flange removable from the front.
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marathonrunner
Posts: 449
Joined: Mon Dec 13, 2010 3:49 am

Re: Air box for Avcon conversions and split cowling

Post by marathonrunner »

Dave I got rid of all those airbox pieces and went with one piece that has been hassle free and doesn’t crack the cowlingvarea
It's not done till it's overdone
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ghostflyer
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Joined: Mon Apr 21, 2008 3:06 am

Re: Air box for Avcon conversions and split cowling

Post by ghostflyer »

I used Harry’s STC and used all the parts supplied that’s what in the bottom of the drawing but he used a different intake cowling with 2 intakes . However Harry,s drawing never included where to put the blisters . It was a measure yourself and guess. However with the 2 intake hole system there was a problem with the right hand intake position. My no3 used to run about 100degs hotter than no1 in cruise . It was only in a steep climb that my CHT,s stabilized cooler.[strange] ,after a big bird strike and being unable to purchase a new intake a rebuild had to be done . The intake internal design had a slight change done to it so a larger mass airflow can occur with a greater duct pressure recovery internally. With no1 cylinder so close to the intake originally ,I felt the airflow was choking and only cooling no 1. So flight testing will occur next week . However when looking at later drawings of the intakes I noticed that a change has been made to the drawings and looking at aircraft at the convention this change has been incorporated in later STC,s issued . [with the same number STC].

Please note. The Bradley mod had been done to the baffling at the factory so airflow around no3 wasn’t the issue.
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