LettersFromFlyoverCountry

LettersFromFlyoverCountry

Well Known Member
I finally got the oil cooler bracket doubler and such finished. I got it as high as it could go and, because it's a slightly larger cooler than standard, couldn't go inboard too far because of the interference from the engine mount (I -- or rather Pete Howell -- cut the flange away).

Everything fit great until I noticed this...

nutplate_cooler.jpg


The lower nutplate hitting the cylinder fin in this lovely IO-360 from Mattituck. I tried grinding bit of it away but it's still not going to be good. Building buddy Brad Benson suggests getting rid of the nutplate and finding a low profile nut, but I'm not sure that's not going to interfere either.

Anyone else ever had a problem with this location?
 
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Bob,

I think I would lose the whole nutplate.

Two screws on the inboard and 3 or 4 on the outboard is plenty,
just so you put a doubler on the outboard corner.

My .02
 
Yep same here 4 bolts total.... top 2 bolts on the I/B side and top and bottom bolts on the O/B side (I used large diameter washers and nuts rather than nut plates)

IMG_4379aa.jpg
 
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//just so you put a doubler on the outboard corner.

Yes, I put a .125 hunk of aluminum as well as the .063 (I think it was .063) spacer. on the outside corner.

The only problem with losing the bolt entirely is that it's the center of the the flange that's cut away to clear the engine mount, so there would only be one long bolt and one short one here.
 
How about relocating the lower inboard mounting hole

How about relocating the lower inboard mounting hole. The inboard and outboard mounting flanges of the oil cooler are just two parallel flanges on the oil coolers I have had and I assume the same is true for yours. If there is room above the current inboard lower mounting location and the flange cutout I would carefully relocate that mounting location upward. This would require drilling new holes in the oil cooler flanges and the baffle and relocating the platenut installation. That is the easy fix. Beyond that you have to get more creative and I am reluctant to make suggestions at a distance for someone else's airplane. I will say there are options that you can come up with to anchor the inboard side of the oil cooler with at least two fasteners if you think about the requirements and the constraints. These kinds of awkward situations are where we builders earn our spurs.

Bob Axsom
 
It might be possible to move that hole higher but just looking at the picture, it looks like it'll have to come up a fair amount to clear the fins, looks like there's only about 3/4" before the nutplates would collide. I'll get the tape measure out.
 
Bob Collins said:
It might be possible to move that hole higher but just looking at the picture, it looks like it'll have to come up a fair amount to clear the fins, looks like there's only about 3/4" before the nutplates would collide. I'll get the tape measure out.
Click to expand...

Move it upwards and reorient the nutplate (angled 45 degrees or so) or use a one-legged one, attached sideways instead of verticallyl?
 
Vlad said:
Double checked, not found
Click to expand...

That's the one I have. It was drawn in 2001. The OP-27 that comes with Van's baffle kit, however, is a newer drawing and shows three bolts on each side instead of two.

Also worth noting that Van's drawing puts the oil cooler VERY low on that baffle, while the instructions note to get it up as high as possible, which is why the middle of the flange (at least on an "A" model) is ground away rather than the top, as in this picture.
 
Bob Collins said:
That's the one I have. It was drawn in 2001. The OP-27 that comes with Van's baffle kit, however, is a newer drawing and shows three bolts on each side instead of two.

Also worth noting that Van's drawing puts the oil cooler VERY low on that baffle, while the instructions note to get it up as high as possible, which is why the middle of the flange (at least on an "A" model) is ground away rather than the top, as in this picture.
Click to expand...

Bob,

I have Van's baffle kit circa last year, and my OP-27 looks like the picture Vlad posted: two bolts on the outboard side (I'm using three) and two bolts on the inboard, one short and one long, with the bottom inboard hole ignored. If I was in your shoes, I probably would just close up the offending baffle hole and build on.

mcb
 
mburch said:
Bob,

I have Van's baffle kit circa last year, and my OP-27 looks like the picture Vlad posted: two bolts on the outboard side (I'm using three) and two bolts on the inboard, one short and one long, with the bottom inboard hole ignored. If I was in your shoes, I probably would just close up the offending baffle hole and build on.

mcb
Click to expand...

I can do that. The question I have, though, is whether there would be a problem having only ONE bolt on the most inboard flange since the aft flange has been filed out so that the middle hole is removed from it -- to allow it to fit with the engine mount. I wonder of a doubler that skirted around the gap would help (of course, part of it would block the cooling area.

I stuck a few more pictures here.
 
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Bob Collins said:
I can do that. The question I have, though, is whether there would be a problem having only ONE bolt on the most inboard flange since the aft flange has been filed out so that the middle hole is removed from it -- to allow it to fit with the engine mount. I wonder of a doubler that skirted around the gap would help (of course, part of it would block the cooling area.
Click to expand...

Hmm, I see now. It's hard to tell from the photos, but I tend to agree with Bob Axsom here - you might try drilling a new hole through the inboard oil cooler flanges (fore and aft) at the convenient location to your particular setup. Barring that, it seems to me like it might be okay to have the inboard side of the cooler attached only via the forward flange, with short bolts, if that's the only thing that will work.

I feel your pain, by the way, as I just scrapped my entire #4 baffle assembly and ordered new parts so I can move my oil cooler to a better position! I'm starting to think it would be easier to build a second canopy instead of these darn baffles... :rolleyes:

mcb
 
To bring this to a close, and to provide some guidance to people who haven't come to this yet...

On the advice of both Mahlon Russell at Mattituck Teledyne and Ken Scott at Van's, I drill out the lower nutplate and covered the hole and will go with two bolts on the right side.

oil_cooler_apr_18.jpg


The Van's instructions with the baffle kit are very contradictory here, so I'll pass this along for people who haven't go this way before.

The main problem in this location is the pre-punched parts that come with the Van's baffle kit and the optional oil cooler doubler. The doubler is prepunched and has three holes for the bolts on the right side. OP-27, the drawing, shows only two.

There's also a brace that goes in the front of the oil cooler doubler/baffle area. This is also pre-punched and is supposed to match the pre-punched holes across the top of the oil cooler cutout doubler.

If you do as I did -- take Van's advice and wait to do the oil cooler brace until the baffling is done -- you'll likely end up in trouble, at least if you do the oil cooler cutout and drill for the doubler. You'll have to drill out the top row of doubler rivets because the brace's holes won't line up with them. The brace can only go in one way, but the location of the oil cooler could be any number of places.

So do the oil cooler cutout, match drill the oil cooler doubler with the exception of the top row of rivets, fit the brace, backdrill the five or six holes through the the brace, the baffle, and the cutout doubler.

You'll also want to leave the most-aft rivet hole unriveted on the horizontal angle/stiffener on the #4 cylinder baffle because if you rivet this, you'll find it hard to fit the brace for final drilling.

Also if you use a .125 angle to beef up the corner, you'll probably have to abandon one of the holes in the doubler since it will interfere with the angle.
 
mburch said:
Barring that, it seems to me like it might be okay to have the inboard side of the cooler attached only via the forward flange, with short bolts, if that's the only thing that will work.
.....mcb
Click to expand...

That's exactly the setup on my O-360 Tiger. It also uses AN526 low profile head screws for the inboard locations for less interference with the cylinder.

tiger-oil-cooler.jpg


Note the thick doubler strip (11) against the soft lower flanges of the oil cooler
 
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Niagra 20003. I probably wouldn't have chosen this particular cooler if I had to purchase one but a very nice person won one from the Minnesota Wing of the VAF (now Twin Cities RV Builders Group) years ago because I "let" him stop by the house when I was first building to see the project. Since he wasn't building -- dreaming -- he gave it to me and it's been sitting on the shelf for a few years.
 
Fatigue cracking prevention tip

Bob,

One other piece of advice if you're not already aware of it is to install washers both ends of the spacer tubing running between the oil cooler flanges. (washers to be installed in the inside flanges of oil cooler) If you don't install these, you run the risk of having these flanges break off as documented by Dan Checkoway some time ago. Installing washers here will spread the load across the flange and seems to prevent fatigue cracking of the flange over time.

Cheers and good luck,:)

Greg (RV-7A IOF-360, WW200RV)
 
nut plate interference

From a totally ignorant guy, why not just grind a little cooling fin away to prevent interference. Have seen this done a lot on motorcycles. Does this create a stress riser? Can't imagine this would have a serious effect on cooling?.Or am I missing something.?
 
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