The International Cessna 170 Association

Folks with a '52 or earlier inner pressure cowl. I need the distance from the underside of the center flat sheeting to the mid point of the bracket holes. See the red arrows. The blue arrow is the measure I need.

Our front bracket was long ago broke and repaired. I think the repair has the center section sitting to high because the outer cowl lays on it and over the years has worn much of it away.

Anyone have easy access and can measure this for me, I'd appreciate it. Even if it is only a close measure I could use it to compare to mine.

Thanks

I can get that measurement for you, but probably not until Thursday.

Bruce,
Maybe I can save Steve a trip. Mine has been repaired but I believe the dimensions are correct. The two inches I measured are from the top of the bolt to the top (as pictured, actually the bottom) of the .040" metal which attaches to the center plenum sheet. So the distance to the center of the hole should be 1.877". Plus .040"=1.917"

Steve and Gary, thank you VERY much. Gary, outstanding picture. This is perfect.

The bolt hole ears where long ago broke off of mine and repaired perhaps as long as 40 years ago. In that time the center cowl has worn the entire V off the bend (rudder type) skin on the top of this piece by the center cowl where it is bend down and the hinge is attached. Basically only barely leaving the hinge. Of course a picture would be worth a thousand words here but I don't have one. I'm hoping to stop the wear. And yes a new inner baffle and cowl would be nice but not in the picture.

What I think happened is either the repair was a bit long raising the baffle to high or the ears that where added and added to the inside of the stand making it to narrow to bridge the case, caused the top center to bow up towards the outside when the bracket was force over the engine case halves. Probably a little of both. Again a picture would save typing.

I concur with 1-7/8 height to the center of the hole.

Full disclosure: The photo is of an owner-produced part that I made in 2004. I also measured the broken original (which I believe to be an original part), and it measures the same.

Gary and Steve or anyone else with this part close at hand.

Decided maybe I will remanufacture this entire center section. My part is made with a flat sheet of aluminum sandwiched and riveted to same size sheet of aluminum with V ribs like rudder or ailerons. Then edges of both sheets are folded over on the long sides to make a channel for the left and right side opening lids.

Looking at Gary's it looks to be made the same. At least it has a flat sheet, not sure but bet the corrogated sheet is on the other side. Is this what you have Gary? Gary's is for a '52

Steve's only has the corrogated sheet that I can see. Is this right Steve? Steve's would be for a '48

Where they made different in different years? Same part number '48 and '52

Bruce,
Mine doesn't have any corrugated sheet. The long edges are folded like you describe. The fold radius is so tight it had to have been done in the -O or annealed condition.

Really Gary. So one sheet of what? 020, 025 thicker?

I'll check when I get back from work but I would guess .032" or even .040"

Mine is not double layer, only the v-ribbed sheet.
Mine is an owner-produced part, copied from what I thought was original (but who can ever be sure).
My aircraft is a pretty early one (S/N 18073).

I will be back at the hangar tomorrow, and can measure thickness of the both the current and the old one. I have an good friend who also has a '48, and can ask whether his is a double layer.

Steve and Gary. This is great info. Maybe we have discovered yet another unknown difference in 170s. Steve and other '48 owners, lets see if we can make a more definitive observation of what the '48 had. Others with '52s lets look at this and see whats out there.

I have a a feeling that Steve's is missing the flat sheet and Gary's is missing the corrugated sheet and built from thicker material to make up. Hope we can figure this out quick. I started drilling mine apart for the overhaul today.

I'll grab some pictures of my '48 the next time I'm at the hangar. The condition of my pressure cowl is better than just about anything else under the cowl, so I suspect it is relatively new but there isn't anything in the logs.

No extra rivet holes in my '52 center piece.

So my partner Leroy thinks ours was so just the one sheet of v ribbed aluminum and that the previous owner who we both know, wrapped it with the second sheet to repair the folded edges. Looking at the rivets I can believe they are not Cessna and this is exactly how my part came to be. So likely, Cessna used v ribbed stock only and the only thing to figure out is did they stop and use a flat sheet by '52 or is Gary's a repair replacement part.

I'll likely repair with just a flat sheet and so Gary, I'd be interested in how thick yours is. Also I note Airforms uses flat sheet wihich looks like L ribs if anyone could give me the placement and dimensions of the L ribs that would be great.

Bruce, I checked my plane today. My '52 has a single sheet of the ribbed aluminum like in the figure you posted. The pressure cowl looks to be original and nothing in the logbook indicates that the original was ever replaced. In fact, it's in such an state that I am replacing it at my next annual in June. The aluminum is pretty thin and some of the folded edges have separated. So I can understand how someone could add a second sheet as you mentioned.