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Lower cowl install with MT 3-blade prop

JackinMichigan

Well Known Member
Last night was the first time we attempted to install the lower cowl with the prop in place (MT 3-blade composite). We found it near impossible to do without removing the spinner cone and several of the attachment brackets, and we stripped out the head on a couple of screws in the process. We did extend the front landing gear slot as recommended by several people.

I suspect this is going to be an ongoing issue, and I just want to ask the more experienced community if there's an easier or better way to do this. Did you construct any special tools or jigs? What is the best order of assembly (top cowl first or bottom)? How do I get the piano hinge pins installed without buggering up the paint job? Our plane isn't painted yet, but we had to do a fair amount of prying in order to install the second cowl's firewall hinge pin.

As I'm sure everyone knows removing the lower cowl is essential to maintenance, and I want to get it down to a choreographed science so there's minimal damage and frustration. I think maybe a YouTube instructional video is in my future.
 
If the nose gear slot is cut far enough fwd to allow lowering the front of the cowl to easily clear the prop blades, the removal/installation shouldn't really be much more difficult than with a two blade prop. It may be that you just need to cut the slot longer, but it could also be some other factors (inlet seals that are bigger than optimal, baffle inlet ramp to cowl inlet gaps that are too small, etc.)
The need to do prying to insert cowl pins is a concern. Particularly in the context of longevity. Pre-load on hinges is what kills them in short order when coupled with vibration.
 
I have no experience with the cowl, but if you haven't, spray some silicone or something on the hinge pins to lube them, trying to push dry pins in is always a bear.

Lynn
 
Last night was the first time we attempted to install the lower cowl with the prop in place (MT 3-blade composite). We found it near impossible to do without removing the spinner cone and several of the attachment brackets, and we stripped out the head on a couple of screws in the process. We did extend the front landing gear slot as recommended by several people.

I suspect this is going to be an ongoing issue, and I just want to ask the more experienced community if there's an easier or better way to do this. Did you construct any special tools or jigs? What is the best order of assembly (top cowl first or bottom)? How do I get the piano hinge pins installed without buggering up the paint job? Our plane isn't painted yet, but we had to do a fair amount of prying in order to install the second cowl's firewall hinge pin.

As I'm sure everyone knows removing the lower cowl is essential to maintenance, and I want to get it down to a choreographed science so there's minimal damage and frustration. I think maybe a YouTube instructional video is in my future.

As someone who has the same configuration you do, I can attest to the fact you must remove the spinner and the two "lower" (usually at 4 and 7 o'clock) spinner brackets that attach behind the blades in that position.

Extending the nose gear slot is a must but it's still a PITA to remove the lower cowl. I find myself using the backs of my hands as "padding" between the blades and the top edge of the lower cowl. I figure flesh can heal.
 
As someone who has the same configuration you do, I can attest to the fact you must remove the spinner and the two "lower" (usually at 4 and 7 o'clock) spinner brackets that attach behind the blades in that position.

Extending the nose gear slot is a must but it's still a PITA to remove the lower cowl. I find myself using the backs of my hands as "padding" between the blades and the top edge of the lower cowl. I figure flesh can heal.

Clamp a microfiber towel to the front of the cowl so it protects the prop from the cowl or vice versa.
 
I can't attest to your situation if you are using the stock cowl, I have the Showplanes cowl with an extended slot and the fairing that fills it in.
No matter what, it's a pain. I don't have to disassemble anything. I do have paint protection film on my gear leg, which is crucial once your plane is painted. If it's two of us, it's a mild pain. If I have to do it by myself, I put a towel on the gear leg and let the cowl "ride" down the leg while keeping the front low enough to clear the prop...
I also did Skybolts on the firewall, and if I had to do it over again, I'd put them on the on the sides as well. The hinges are awful.
 
Glad to here it...

I went back and forth on the side hinges for awhile. I ended up doing skybolts instead...they look good and it takes literally a minute to unlock them and remove the top cowl.

I have the showplanes cowl. Now I have to figure out the length of the slot needed to remove the lower cowl with the prop on...(I used a spinner jig to fit the cowl)
 
I went back and forth on the side hinges for awhile. I ended up doing skybolts instead...they look good and it takes literally a minute to unlock them and remove the top cowl.

For others still trying to decide.... I can remove the top cowl of the RV-10 prototype (with per the plans hinges) in about the same amount of time.

As with anything (including camlocks) proper installation is going to have a big influence on the level of difficulty involved for cowl installation/removal.
 
Hinges

Personally, I thought the skybolts were easier to install than the hinges would have been, what with messing with the joint where the end of the hinge pin must be retained, not to mention twice the rivets driven. Oh, and trying to PUSH a wire through 39" of hinge knuckles...twice. We're the skybolts more expensive? Absolutely...but for me, the convenience and ease of removal and installation was worth the added cost...

I love experimental aircraft...
 
Sorry to hear you are having problems. I've built 2 of the 10's and installed 3-bladed MT's on both of them, and installed 3-bladed MT's on others. I've never had to remove the spinner. I do have the slot lengthened on the bottom cowl, and then covered with a filler plate when it is installed, and I do remove the nose gear fairing.
Scott is right on that you don't want any preload or the hinges will break for sure. I've always used a .040 or stiffer plate across the aft bottom cowl, riveted to the fueselage in place of the hinges, and then 6 each 10/32 screws across each bottom, left and right of the exhaust stacks. It seems to carry the load better (the 10 cowl is heavy). On 10's with the hinges they seem to need replacing every so often.

The slot for the nose gear begins 10" AFT of the inlet scoop on mine.

Vic
 
You might also talk to Saint Aviation....They have a neat way of splitting the bottom cowl in half for ease of removal.
 
No, it's not easy.......:D

However, i have now got the knack and can do it relatively painlessly with 2 people without disassembling anything else. Bit late now, but a decent gap between the spinner and cowl helps - I have 1/4 to 3/8". Second, you must extend the gear slot by about 10" (sorry, can't measure right now) and use a removeable cover plate.

Start with the cowl tilted up at the back and (pretty obviously), the lower blades at 4/8 o'clock. You should then be able to slide the cowl over the gear fairing and under the blades. Then tilt it so that the back is slightly lower, get it as far back as possible and bring up. The baffle seals around the air intake are going to foul underneath the baffle ramps and it takes a fair amount of "persuading" to get them past. Some people recommend using stiff wire to pull them through but brute force also works..... It is a tight fit behind the spinner but it will go. Once you get here, you are home and dry and it just requires a bit of jiggling to get it in place. Make sure you have all the baffle seal material lying in the right place before you start fixing anything.

Hope this helps. You'll love the prop.
 
You might also talk to Saint Aviation....They have a neat way of splitting the bottom cowl in half for ease of removal.

I wonder if Jesse could be persuaded to post some pics or a video demonstrating the split lower cowl configuration.

Threads like this cause me to make mental notes-to-self, such as: 1) skip the hinges everywhere on the cowl. Buy once, cry once.

2) sexy three-blade props cost more to go slower. Don't set yourself up to wrestle the lower cowl off around one of these beauties, or you'll skimp on good maintenance and inspection habits to avoid the hassle.

Maybe Jesse has a workaround for the above with the split lower cowl. :confused:
 
sexy three-blade props cost more to go slower. Don't set yourself up to wrestle the lower cowl off around one of these beauties, or you'll skimp on good maintenance and inspection habits to avoid the hassle.

It's not just about being "sexy". Yes, the 3 blade is supposed to be a few knots slower in the cruise but take-off and climb are supposedly improved. My AP looks after several RV-10s and mine is the only one with the MT prop - he has remarked on several occasions about how smooth it is. The composite prop just takes away all the harshness. I'm happy to trade a couple of knots for less vibration.

Yes, the lower cowl removal can be a PITA but it only took me a few removals to get the hang of it. Whilst I am sure it is not as easy as the 2 blade, it is no longer a major issue. All things being equal, it only has to come off at the 50 hour oil change. Since that can't be done without removing the lower cowl, I fail to see how any inspections can be skimped on.......
 
And...

I find it kind of amusing the talk about the 3 blade being a couple of knots slower in cruise seeing as a bunch of people fly the ten at less than max speed anyway, to get the fuel flow lower...

Thought about the two blade and opted for the MT three blade...
 
MT prop and Skybolt

Was wondering if anybody has installed the Skybolt on the horizontal cowl split line that has a 3 blade prop.
It was brought to my attention that you cannot get the lower cowl off if you have both the 3 blade prop and the skybolt fasteners.
The reason is the lower cowl apparently wont fit under the prop with the skybolt flanges sticking up.
Thanks for any help.
 
cowl

I have the showplanes cowl with skybolts at all joints.

The showplanes cowl allows for a substantial slot in the lower cowl allowing it to
drop almost straight down. I don't think it will be an issue...
 
Follow Vic's post suggestions. I did that and it works great. I wouldn't split the cowl in half. I have to believe a split cowl hinged together for installation must be weaker than a not split composite cowl. The value of the 3-blade MT outways the additional few modifications noted. You will be happy with the end product.
 
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