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Lower cowl fitting after prop mounted

Aiki_Aviator

Aiki_Aviator

Well Known Member
I have an issue with the fitting of the lower cowl now that I am up to final assembly. I have now final mounted the prop and need to find a way that allows for easy assembly of the lower cowl without completely disassembling the prop.

Have people had the same issue after following Vans plans? What did you do to fit the prop? Did you make additional cuts?

Did anyone disassemble the prop spinner mounting plate to complete the cowl fitting?

Pictures would be great.

Thanks in advance
 
Aiki_Aviator said:
I have an issue with the fitting of the lower cowl now that I am up to final assembly. I have now final mounted the prop and need to find a way that allows for easy assembly of the lower cowl without completely disassembling the prop.

Have people had the same issue after following Vans plans? What did you do to fit the prop? Did you make additional cuts?

Did anyone disassemble the prop spinner mounting plate to complete the cowl fitting?

Pictures would be great.

Thanks in advance
Click to expand...

Have you made any cuts to the lower cowl yet? Are you attempting the initial fitting?

I'm confused by your statements, since you don't need to remove the prop or mounting plate to fit the cowl. Are you having issues getting the cowl on? Is it hitting engine accessories? It is an acquired skill getting it on, but it is possible.

My recommendation is to us 1/4" spacers instead of 1/8" spacers per the plans. The cowls are quite flexible and if you aren't careful you can compress them a bit. I used 1/8" spacers and had the top cowl pop forward and consumed the gap when I removed the spacer. I had to do a little work on the forward part of the cowl to compensate, since I made all the other cuts. 1/4" spacer gives you a little more room for error.

Some folks also position the cowl so that the spinner sits about a 1/8" proud on top in anticipation on The Lord mounts compressing ove time, dropping the prop a bit. It really depends on how long you engine has been mounted.
 
I have a 3 blade prop on my 8A and removing the lower cowl is a real pain.
to solve this issue, I cut the scoop off the cowl and glassed a flange on the removable scoop, installed #8 nut plates on the inside of the cowl to attach the scoop. Now with the scoop removable the cowl is a snap to take on and off.
 
With a 3-blade prop is, I'm afraid, a real PITA.

I have cut a longer slot in the bottom as most have, with a screw-on cover. That makes it relatively easy to get it in position below the spinner. However, on the MT prop, the spinner protrudes back about 1/2" behind the back-plate. I have to take the spinner off to get the lower cowl on - at least, I haven't found a way yet to do it without taking it off. Even then, it's going to be difficult not to scratch paint when it is done.
 
I cut a longer slot in the lower cowl that allows it to tilt and slide under the three-blade prop a lot easier. It still takes careful alignment and a second set of hands. I also use a piece of rubber edging on the prop edges to protect it from scratches during off and on tasks of the cowl. The longer slot is reinforced with a metal doubler. Details on my blog at: http://myrv10factory.wordpress.com/...-oil-door-egtcht-wiring-and-ignition-routing/
 
Andrew.
Posts above all have good suggestions. It is tight fit and I would add that the inlet ramp baffle should be cut to allow for clearance when lowering the cowl. If it is too close it will want to force the cowl into the spinner back when the baffle seal drops past the inlet ramp. I used the baffle seal from mcfarlane which added complexity because of the material flexibility.
 
Lower cowl installation

Andrew,

I am struggling with same problem as you. I am close to final assembly and cannot figure out how I am going to get the lower cowl installed with that prop spinner in the way.

I am hoping some one out there has one of those brilliant yet simple ideas to solve this problem.

Failing that I think I am going to trim the inlet ramps and the fiber glass where the baffling attaches to gain a little space.
 
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I have no specific recommendation, but I'd sure encourage finding some way to make cowl R&R easier. Forget the instructions or lack of them; you're the manufacturer, so figure it out and build what you need. It's a safety issue. Simple human nature says if the cowl is hard to remove and replace, the operator(s) won't do it very often. Lack of regular visual inspection is a very bad thing.

"Access for maintenance and preflight" is found in two of the nine areas on the standard EAA judging form. It's important.
 
On my -10 with a two-bladed Hartzell, I had to cut the lower inlet ramps back so that the cowl could drop vertically while the rubber seals simply folded up as the cowl went down. Surprisingly easy to do.

On three blade airplanes, a removable scoop is a good fix.

Best,
 
I know I am just repeating the above posts, but there are three items that will make the removal much easier. It will still take two people so as not to scratch the paint, etc.

1. Trim the lower cowl inlet ramp back to have at least an 1/2-3/4 inch gap when the cowl is installed. You can do this with a combination of trimming the cowl and the actual metal ramp. The lower portion is all that needs to be trimmed. Fill in the gap as called out in the plans. Use the material provided, if you try to use a thicker silicone baffle material it will defeat the purpose of the gap.

2. Extend the lower cowl opening for the nose gear strut. I don't recall how exactly much I extended mine, somewhere around an inch or two.

3. When you fabricate the baffle seal for the FAB, attach the upper seal to the FAB inlet, and the lower seal to the cowl inlet. This allows for no interference when installing the cowl. I posted a couple of photos below

IMG_2646.jpg
IMG_2337.jpg
 
What Bill said. In addition, I made from 0.020 sheet acetate a disk that looks like a giant washer with a slit along one radius. I slip this over the prop shaft between the aft edge of the spinner and the forward face of the cowl. It protects the paint on the cowl from scratches.

Jim Berry
RV-10
 
I have had 3 RV's in the shop in the past year that had the scoop on the lower cowl be removable. In my opinion it's a fantastic idea. Makes getting the lower cowl on or off so easy, even a caveman could do it.
 
I have worked on a -10 with a 3-blade MT that has the bottom cowl in 2 pieces. It splits right down the middle. The really nice part about that is that you can pull off just one side if you want to work just on that side. It would take a guy who enjoys fiberglass to go that far, but it makes service really nice.
 
lower cowl install

Piere/Bill,

Thanks for the suggestions.

A question for Bill. Are you happy with the location of foil heat reflectors on the inside of the lower cowl. Given another chance would you place them any differently?

Thanks in advance.
 
Alan,
I have subsequently added additional heat shield to compliment what is shown. I don't have any photos. I wanted to make sure I didn't have any paint issues from heat.
 
KTM520guy said:
I have had 3 RV's in the shop in the past year that had the scoop on the lower cowl be removable. In my opinion it's a fantastic idea. Makes getting the lower cowl on or off so easy, even a caveman could do it.
Click to expand...

Yes, and it becomes possible to install a really positive seal at the airbox inlet. Can't know how much without measurement, but a poor seal should raise lower cowl pressure and reduce potential MP.
 
Thanks all.

Great feedback.... per normal.

I will look at extending the slot and if required make an additional plate to secure back to the same location it is currently occupying.

Thanks everyone for thier comments.
 
What works for us is to remove the nose gear fairing, install the tail tie down ring and pull the tail down until the pressure is off the nose gear. It makes it a lot easier to install and remove the lower cowl.
 
One sure way that worked well for me is to extend the inlet snout by 1 inch over the recommended length in the plans and cut the FAB front end shorter by 1 inch.

DSCF2155B.jpg


Also cut the cowl flanges at the corners. This will make a big difference.

DSCF1738B.jpg
 
Many good ideas here ...

Absent some kind of major surgery, the key is make the nosegear slot as long as you possibly can. To know for sure, buy the nosegear intersection fairing whether you need it right now or not. Then you know exactly how long you can extend the slot without it being visible from the exterior. I struggled with my lower cowl until I extended the slot at least 2 to 3" further than what Vans said in the plans ...and I still have another 1 1/2" remaining under the intersection fairing.
 
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