lower cowling removal difficulty 9A+3-blade

are there any 9A+3-blade combination owners out there who've solved the dance of getting the lower cowling off without scratching the paint (new, in my case) off either the cowling or the plane or the prop between the nose gear, spinner, prop blades and fuselage...... maybe this is my excuse to convert to constant speed...?

or modifications or the cowling to accommodate this particular combo?

sincerely,

dan

I have a 3-blade catto prop but do not have any overly difficult problems when removing the cowling. I make sure one of the blades is pointing straight up in the 12 o'clock position. This allows for the other two blades to be in the 8 o'clock and 4 o'clock positions. With the prop in this position I stand directly in front of the spinner and grasp the lower cowl on each side. Then I slowly begin sliding the lower cowl down and forward while keeping the cowl pitched pretty close to the normal mounted position. Once I slide it forward enough for the 8 and 4 o'clock blades to come close to the hinge eyelets on the upper edge of the cowl edge I will slowly begin to pitch the tail end of the cowl down towards the ground and slowly let the cowl come forward. This will allow the cowl eyelets to gently slide below the two prop blades. Once I have an adequate amount of clearance from the prop I continue pulling forward with the cowl until there is a point where the eyelets are no longer at risk of hitting the prop. At this point the cowl will easily clear the prop blades.

I will say I did cut out the nose gear slot on the lower cowl further forward than the standard plans call for. There is a bulbous cutout on the fore end of the slot and it is a bit longer than I think may be called out for in the plans. Once I had the correct amount cut out I fabricated a cover plate to fill in the cowl slot. The plate completely covers any openings once everything is secured in place. I am not sure I have any pictures of this setup or not. I am due to change the oil soon so perhaps I can remember to snap some pics of this setup.

Hope this helps.

Glad to see I'm not the only one !

...that struggles to get the bottom cowl on and off! I dread that task every time it arises. I have a couple of paint scratches (not deep) on the back of the prop resulting from the removal process. I have a Sam James long cowl with a 4" prop extension ... I thought my remove/install problem was thus not shared by the Vans cowl owners. Looks like I was wrong.
I have the nosegear slot cut per the Vans specs, but after reading this thread, I'm thinking I may extend it a bit. With an assistant, installation is not bad at all, but solo it's a PITA.

RVbySDI said:

I have a 3-blade catto prop but ..... I make sure one of the blades is pointing straight up in the 12 o'clock position.... in the 8 o'clock and 4 o'clock positions. .... I slowly begin sliding the lower cowl down (the nose gear leg fairing?) and forward while keeping the cowl pitched pretty close to the normal mounted position. Once I slide it forward enough for the 8 and 4 o'clock blades to come close to the hinge eyelets on the upper edge of the cowl edge I will slowly begin to pitch the tail end of the cowl down towards the ground and slowly let the cowl come forward. This will allow the cowl eyelets to gently slide below the two prop blades. Once I have an adequate amount of clearance from the prop I continue pulling forward with the cowl until there is a point where the eyelets are no longer at risk of hitting the prop. At this point the cowl will easily clear the prop blades.

I will say I did cut out the nose gear slot on the lower cowl further forward than the standard plans call for. There is a bulbous cutout on the fore end of the slot and it is a bit longer than I think may be called out for in the plans. Once I had the correct amount cut out I fabricated a cover plate to fill in the cowl slot. The plate completely covers any openings once everything is secured in place. I am not sure I have any pictures of this setup or not. I am due to change the oil soon so perhaps I can remember to snap some pics of this setup. (that would be cool... or you don't even have to take it off just snap a pic from where you'd be standing, looking up at the nose and slot from in front of the nose wheel. how far aft of the back edge of the spinner is the slot extending forward?)

Hope this helps.

Click to expand...

that is pretty much the technique i've tried to employ. i've only got about 3/8" between my cowling and the rear edge of the spinner, barely enough to clear the piano hinges at the rear, then i lower it straight down until it is resting on the nose gear leg fairing, and it is here that i run into trouble. tilting it forward get mixed with the back of the spinner, blades tilting it back gets the hinges messing with the fuselage where i now have protective tape. i think i'm going to have to extend the nose gear slot further forward to allow a significantly greater vertical drop before any forward movement of the cowling takes place. GREAT IDEA.... thanks!

i've even tried lowering the tail to take all the weight off the nose gear to let it spring down as far as possible.... but i still managed to carve another scratch. i've even contemplated making it a three piece cowling by splitting the lower cowling into two pieces..... but extending the slot, if only temporarily and fabricating that removable piece is probably the most practical solution.

i guess i'm still gonna have to wait for the constant speed prop.....

I have the same problem getting the lower cowl off of my -10. In addition to what has already been mentioned, I made a protective disk that fits between the back of my spinner and the forward face of the cowl. Made of 0.020 acetate sheet, approx. 18" diameter, with a 9" diameter hole in the center. Cut along one radius, so that it can be slipped over the prop. Does a great job of protecting the cowl from spinner scratches. I also put a layer of duct tape on the forward edge of the fuselage skin, just aft of the aft edge of the lower cowl. No new scratches in my beatiful GLO paint job since I started doing this.

Jim Berry
RV-10

Another solution, during the build/cowl-fitting, is to completely remove the lower intake snout and re-attach with camloks.

A friend of mine has this setup on his three-bladed -10.

Best,

A rubberised 'bib' helps

A pal of mine has a 9A with a Catto 3 blade and a beautiful paint job (self-painted too). I spent a day at his hangar some time ago while he worked on his plane and this is how he protected the prop while getting the cowl off: I think the black 'bib' was made from the type of material used for soft-sided semi trailers. There is a cut from the bottom edge to a central hole and the two sides of the cut are held together with the string laces you can see hanging down (yes that is carpet tile on his hangar floor)



Perhaps there was another bib for the front gear leg but I don't recall.

One of those cheap door mats with carpet on one side and rubber on the other would be an ideal substitute material but I'm sure almost anything you have lying around would do just as well.

Mike, if you see this, I hope you don't mind me broadcasting some of your great ideas

flylevel said:

that is pretty much the technique i've tried to employ. i've only got about 3/8" between my cowling and the rear edge of the spinner, barely enough to clear the piano hinges at the rear, then i lower it straight down until it is resting on the nose gear leg fairing, and it is here that i run into trouble. tilting it forward get mixed with the back of the spinner, blades tilting it back gets the hinges messing with the fuselage where i now have protective tape. i think i'm going to have to extend the nose gear slot further forward to allow a significantly greater vertical drop before any forward movement of the cowling takes place. GREAT IDEA.... thanks!

Click to expand...

I have a pic of the cowl I took last night. I will try to post when I can but right now I cannot get it uploaded with the iPad.

flylevel said:

... i've only got about 3/8" between my cowling and the rear edge of the spinner, barely enough to clear the piano hinges at the rear, then i lower it straight down until it is resting on the nose gear leg fairing, and it is here that i run into trouble. tilting it forward get mixed with the back of the spinner, blades tilting it back gets the hinges messing with the fuselage where i now have protective tape.

Click to expand...

You perfectly described the process - and resulting problems - that I have. My problems are not just scratching the so- far-nonexistent paint ... It's trying to clear all the major parts and pieces that get in the way. This morning I extended the nose gear slot another 3/4 in .... I'll know in the next half hour if that helps.

N15JB said:

I have the same problem .... I made a protective disk that fits between the back of my spinner and the forward face of the cowl. Made of 0.020 acetate sheet, approx. 18" diameter, with a 9" diameter hole in the center. Cut along one radius, so that it can be slipped over the prop. Does a great job of protecting the cowl from spinner scratches. (what a freakin' great idea!)I also put a layer of duct tape on the forward edge of the fuselage skin, just aft of the aft edge of the lower cowl. No new scratches in my beatiful GLO paint job since I started doing this.

Jim Berry
RV-10

Click to expand...

i have a huge roll of mylar... i suppose that'd work too

Rupester said:

You perfectly described the process - and resulting problems - that I have. My problems are not just scratching the so- far-nonexistent paint ... It's trying to clear all the major parts and pieces that get in the way. This morning I extended the nose gear slot another 3/4 in .... I'll know in the next half hour if that helps.

Click to expand...

definitely interested in how far aft of the spinner you have to extend your slot

Fairings etc. has a really well done upper intersection fairing for the tri gears that allows you to cut a really long way forward and the slot still be covered up when it's in place.

Best,

As promised ....

I cut the gear leg slot another 3/4" longer (i.e. forward). That either helped quite a bit ... or I'm just getting used to the lower cowl wrestling match. I did not have the interference issues with the prop as before. Now, with just a little rocking of the prop R & L, I was able to thread the cowl up and on ...or as they say, "onward and upward."

(Don't know why I didn't think of that before. Doh!!!)

pierre smith said:

Fairings etc. has a really well done upper intersection fairing for the tri gears that allows you to cut a really long way forward and the slot still be covered up when it's in place.

Best,

Click to expand...

i imagine that would allow for as small of a gear slot and decreased drag due to turbulence, after it is replaced onto the cowling in flight. this might be the best answer so far.

I promised some pics of my lower cowl gear leg slot. I took my cowl off Sunday for an oil change and have some pics of everything but have had trouble getting them posted. Will do so as soon as I can.

Removing my cowl Sunday reminded me of a trick I failed to mention in my previous post that really helps. Once I have the lower cowl free I gently lower the entire cowl straight down and let it slowly slide down the nose gear leg. I am usually standing behind and to one side of the prop when I start the process. Once I have the cowl free from the hing eyelets on the firewall I work my way around until I am standing directly in front of the prop while holding onto the lower cowl with each hand directly on top of the top edges and the hing eyelets on the cowl. As I slide the cowl forward I keep my hands directly underneath the prop blades. This ensures that my hands act as a protecting surface that comes in contact with the prop instead of the cowl eyelets. I can then slowly work the cowl forward until there is just about 6" or so of the aft end of the cowl left below the prop blades. At this point I can tilt the forward section of the cowl up enough to allow the back 6" or so of the cowl to continue dropping down far enough to pull it forward clear of the prop blades. Again, the key for me is to place my hands between the prop blades and the top edge of the cowl so the only thing touching the blades is the top of my hands.

Hope this is helpful. I will get some pics posted as soon as I can figure out what is failing on the upload process.

Great description ...

You just did a nice job describing what I call the "9A/3 blade lower cowl mambo".

Rupester said:

You just did a nice job describing what I call the "9A/3 blade lower cowl mambo".

Click to expand...

i think this "jig" is up.

RVbySDI said:

I promised some pics of my lower cowl gear leg slot. I took my cowl off Sunday for an oil change and have some pics of everything but have had trouble getting them posted. Will do so as soon as I can. Good luck with that..... i'm eager to see.

Removing my cowl Sunday reminded me of a trick I failed to mention in my previous post that really helps. Once I have the lower cowl free I gently lower the entire cowl straight down and let it slowly slide down the nose gear leg. I am usually standing behind and to one side of the prop when I start the process. Once I have the cowl free from the hing eyelets on the firewall I work my way around until I am standing directly in front of the prop while holding onto the lower cowl with each hand directly on top of the top edges and the hing eyelets on the cowl. As I slide the cowl forward I keep my hands directly underneath the prop blades. This ensures that my hands act as a protecting surface that comes in contact with the prop instead of the cowl eyelets. I can then slowly work the cowl forward until there is just about 6" or so of the aft end of the cowl left below the prop blades. At this point I can tilt the forward section of the cowl up enough to allow the back 6" or so of the cowl to continue dropping down far enough to pull it forward clear of the prop blades. Again, the key for me is to place my hands between the prop blades and the top edge of the cowl so the only thing touching the blades is the top of my hands.This is pretty much the same dance that i do.

Hope this is helpful. I will get some pics posted as soon as I can figure out what is failing on the upload process.

Click to expand...

One thing that's complicating my procedure is that i have attempted to replace the scat tube intake from both the cowling intake to the filter and the tubing from the filter to the carburetor. The pre-existing tube from the cowling to the airfilter was always a pain and too short. so i took this opportunity to lengthen it, but may've made it too long. plus i'm wondering if its not actually a 3' but a 3-1/8 or 3-1/16. Either way I need more hands than I have. blah blah blah blah....

pierre smith said:

Fairings etc. has a really well done upper intersection fairing for the tri gears that allows you to cut a really long way forward and the slot still be covered up when it's in place.

Best,

Click to expand...

When I went to "fairings etc." I looked at it and wondered how much movement the gearleg has at that intersection of the cowling and the gearleg. and where to put the attachment screws of the fairing to the cowling for deflective purposes. or... does this cowling not move at all and only the gearleg fairing slide back and forth within the confines of the fixed intersection fairling?

We never saw any evidence of gear leg flexing up high. Most of the gear leg action seems to be in the lower end of the gearleg.

We did use some clear, flap tape around the upper part of the leg fairing, in case there was some movement there but we had the airplane for 500 hours/5 years and trained over 80 guys in it, with piles of landings during all that transition training.

Best,

Well, I finally was able to upload the photos. Below are pics of my nose gear leg cutouts on the lower cowl. Looking closely you can see the outline of the intersection fairing. Looking at that outline you can see where I cut the slot further forward than where the intersection fairing would cover the open space. Because of this I fabricated a cover plate to extend forward of that fairing. You can see how that plate fits into the slot in the second pic. Hope this helps.

Steve, there's supposed to be a rear cowl support bracket that is attached to the lower firewall. It has a flat plate attached to it, horizontally with six screws, three on each side of the slot at the rear.

I don't see any holes there in your cowl.


Best,

pierre smith said:

Steve, there's supposed to be a rear cowl support bracket that is attached to the lower firewall. It has a flat plate attached to it, horizontally with six screws, three on each side of the slot at the rear.

I don't see any holes there in your cowl.


Best,

Click to expand...

Not exactly sure if I have the same plate you are referring to but the third picture shows the two plates my cowl uses. The plate on the left attaches to the support bracket you mention via the two center screw holes. The fiberglass on each edge of the slot in the cowl is basically sandwiched between this plate and a slot in the support bracket. The two screw holes on the aft end of the plate secure the aft end of that plate to the slotted support bracket.

Not sure if I described that very well but I do know my cowl is very securely attached to the support bracket that is mounted to the engine mount/nose gear mount at the exhaust end of the slot.

I found this picture from when I was working on the firewall forward that shows the support bracket for the aft lower cowl. I am not sure if this helps with my above description but basically there are two pieces of aluminum that are spaced apart so that the fiberglass slides between the two pieces on the bracket to fill that gap. Then the plate in the above post is installed on the outside of the fiberglass and fills the remainder of the gear leg slot in the lower cowl. It is secured with two screws that insert into the bracket seen in this pic. I might add there are a total of 8 screws (4 on each side of the exhaust opening) that secure the entire trailing edge of the lower cowl to the firewall flange also. You can just make out the nut plates for those screws on this picture also. They are on the belly skin that protrudes forward of the firewall.

Lower Cowling Modification

Does anyone have pictures of the modification that Pierre Smith suggests above that they could post? I have a -6 with a carbureted engine. My lower cowling is miserable to remove and a big part of the difficulty is getting the air intake snout to slide downward past the intake on the air box during removal. I'm thinking of making a section of the cowling removable in that area. I know I've seen this mod somewhere, but can't remember the details. Thanks.