S

StuBob

Well Known Member
Doing an oil change today and, as always, struggling to get the bottom cowl off without scratching it, scratching the spinner, etc. It seems like the baffles on the front of the air box are too long, too stiff, or both. If there were no rubber there, or if the rubber was softer, it seems it wouldn’t be a problem. As it is, I have to push the lower cowl forward a couple of inches to get it around the baffles, but there isn’t that much clearance between the spinner and the cowl. The only way to get adequate clearance is to lower the aft portion and jiggle the front. Scratches result.

That’s just the removal. Replacement is just as hard. Doing it alone is a non-starter.

This is an RV7 with an O-360-A1A the Van’s carb air box.

This sounds like a Dear Abby letter, so sign me. . . . .
Aggravated at the Airport
 
I had read a lot of posts with similar complaints about the difficulty in removing the cowl due to the stiff rubber baffle material. I used very flexible silicone rubber for my baffles, and that makes removing the cowl much easier. I also strategically place some microfiber cloths around the edges of the cowl that might touch the spinner or the sides of the fuselage to add a bit of protection. Still, I agree completely, it seems like it should be a bit easier - perhaps a place for some innovation by someone clever.
 
There is a trick to install the lower cowling with one person. I don't have a photo yet but I took me about 10 mins to re-install the lower fairing on my RV8.
With regard to the front baffle material, I use masking tape to fold them out of the way and that helped it to clear the inlet ramp. I will post a picture of my contraption later this weekend when I get a chance to visit the hangar. Some people at the airport was saying it was too simple, there is no-way it will work.
 
I made the baffle seals on the inlet ramps removable. This provides clearance to get the lower cowl off.

Sorry - these are only photos I could find but they should give you the idea.

Carl
 

Attachments

  • 20230601_135515.jpeg
    20230601_135515.jpeg
    1.5 MB · Views: 174
  • 20230601_135520.jpeg
    20230601_135520.jpeg
    1.7 MB · Views: 172
  • 20230601_135503.jpeg
    20230601_135503.jpeg
    1.8 MB · Views: 172
  • 20230601_135508.jpeg
    20230601_135508.jpeg
    1.6 MB · Views: 183
On my -10, I split the lower cowl and used skybolts. One person, easy on, easy off. No scratches, no prop interference.

Best mod ever.
 
I agree, removing the cowl, especially the lower cowl with a three blade prop, is a massive effort by yourself. Unfortunately I have scratched and chipped my paint around the back of the spinner on the cowl a little and started to scratch the nose gear fairing. I recently purchased the Antisplat nose gear fairing and find it a useful guard to protect the fairing as I remove the lower cowl. I did have to trim it a bit to get a better fit for my RV7A.

I’ll try just about anything to make this job easier. The Antisplat product does help.

antisplataero.com

Nose Wheel Fairing Protector - AntiSplatAero

Anti-Splat-Aero is very proud to offer the latest addition, to our fine line of high-quality, specialty, problem solving tools and accessories. The A.S.A. “ NOSE WHEEL FAIRING PROTECTOR”. We have made several handmade variations of various covers with different materials (fiber glass...
antisplataero.com antisplataero.com
 
PhatRV said:
There is a trick to install the lower cowling with one person. I don't have a photo yet but I took me about 10 mins to re-install the lower fairing on my RV8.
With regard to the front baffle material, I use masking tape to fold them out of the way and that helped it to clear the inlet ramp. I will post a picture of my contraption later this weekend when I get a chance to visit the hangar. Some people at the airport was saying it was too simple, there is no-way it will work.
Click to expand...
I do a similar thing with mine (RV6), but I use regular black pvc electrical tape. I tape the cowl inlet baffle rubbers folded up over the inlet scoop, 3 pieces of tape on each inlet. Makes it so much easier to fit the lower cowl up into place. After it’s in position and pinned in place, I just pull on the stretchy pvc tape and it pops right out, leaving the front ramp baffle seals in place. I learned this technique from Steve Melton and he has an RV9A, which should be more difficult than my taildragger. My bottom cowl does rub on the prop spinner back plate while doing this because I have a tight fit (3/16”). I put on a couple strip of 3M slippery tape on the face of the lower cowl where it contacts the backplate. It’s very thin, and you can’t see it when the cowl is installed because of the small gap.
PhatRV says it only takes 10 minutes to install his bottom cowl. I’ll bet it’s much less than that if you put a stop watch to it. Mine takes maybe 3-4 minutes if I’m dragging my feet.
Consider using the tape to get the cowl lip baffle pieces out of the way. Slippery tape on the lip works too, at least for me, and it’s invisible when the cowl is on.
 
Zero4Zulu said:
View attachment 59527

I use this contraption along with tape and propeller protection. Plastic sleeves on the prop.
Click to expand...
That TOTALLY illustrates my problem. It looks like this allows you to drop the cowling straight down. Is that it? Because my airbox — or at least the baffling — extends forward such that I have to move the cowling forward to get around it, and that movement is blocked by the spinner.

I really like the idea of splitting the cowl and holding it together with Skybolts or camlocks. I wish a previous owner had done that, but I’m chicken.
 
StuBob said:
That TOTALLY illustrates my problem. It looks like this allows you to drop the cowling straight down. Is that it? Because my airbox — or at least the baffling — extends forward such that I have to move the cowling forward to get around it, and that movement is blocked by the spinner.
Click to expand...
After buying my -9A, I eventually noticed my airbox had no baffling “tube” connecting it to the scoop in the bottom of the cowl. I dutifully installed baffling per the plans. Used flexible silicone baffling material but it still made cowl removal a pain. Eventually the baffling got damaged during a particularly ham handed cowl removal at a remote location. I removed it and flew home, figuring it had flown fine for years without it.

Key discovery, after a before/after analysis using engine analyzer data and the Savvy website: no discernible difference in any measured parameter with or without the baffling. In my carbureted plane, at least, it seems to be overkill. Possibly something the previous owner had already figured out. :ROFLMAO: Cowl removal is much easier without it.
 
I was just going through this last night with my 4.

The rubber surrounding the baffles is quite stiff, and it's a bit of a puzzle getting the snorkel lined up at the same time as everything else.

My approach is to put tape on the cowling where it would contact the spinner, and a line of tape along the skin where the piano hinges meet up. I then start by lining up the snorkel hole, followed by stretching the cowling apart around the top of the gear legs, which can scrape them a little, but only where it's hidden underneath the fairing and has unfinished paint anyway. There's inevitably a bit of swearing, like last night when it all seemed to go smoothly until I noticed one side of the cowling ended up on the wrong side of a baffle. 😅

I like the idea of softer rubber or silicone.
 
After trying to balance on one leg while also trying to hold up the bottom cowl with the other knee, I knew that I needed some help.
My roller seat with a heavy soft tool bag on top of it positioned just forward of the firewall provided the extra hand that I needed.
It was easy enough to lift the rear of the bottom cowl onto the top of the supported toolbag.
After that, I had both hands free to work the front of the cowl into place.
Taping the flexible inlet seals toward the front of the cowl inlets helped also.
 
I've actually successfully used an automotive floor jack with something (box, foam or whatever) on top of it. You can easily adjust height and roll the cowling in under the engine.
Not as elegant as previously pictured contraption because you still have to balance the cowl with a hand.
 
Dugaru said:
After buying my -9A, I eventually noticed my airbox had no baffling “tube” connecting it to the scoop in the bottom of the cowl. I dutifully installed baffling per the plans. Used flexible silicone baffling material but it still made cowl removal a pain. Eventually the baffling got damaged during a particularly ham handed cowl removal at a remote location. I removed it and flew home, figuring it had flown fine for years without it.

Key discovery, after a before/after analysis using engine analyzer data and the Savvy website: no discernible difference in any measured parameter with or without the baffling. In my carbureted plane, at least, it seems to be overkill. Possibly something the previous owner had already figured out. :ROFLMAO: Cowl removal is much easier without it.
Click to expand...
I've wondered about this option.
 
Someone posted a rolling pvc pipe cradle they used along with some plastic carabiner things and pieces of a binder clip to lower the bottom cowling. Works great. I used one my buddy made today to lower my bottom cowl to begin my condition inspection. Try searching for it
 
MED said:
Someone posted a rolling pvc pipe cradle they used along with some plastic carabiner things and pieces of a binder clip to lower the bottom cowling. Works great. I used one my buddy made today to lower my bottom cowl to begin my condition inspection. Try searching for it
Click to expand...
I think I have that included in one of my photo albums. https://photos.app.goo.gl/n8mysr5Xdpu1KLzK9

Some thread URLs are in the title of the album and can be cut and pasted.
 
Last edited:
This is one of the uses for my Harbor Freight hydraulic lift table, blanket on top and pump up to just under the snorkel, release the cowl sides and then try to drop the cowl straight down and clear the baffling on the intake and snorkel. I do tape the back of the spinner and prop blades (3 blade Catto). Still a pain but doable with one person and some 🤬 language. Very interesting comment about the flexible baffling around the airbox intake as I wonder without that there would also be some airflow through the lower cowling, would that help pull more upper cowling air through the cylinders or just add drag?
Figs
 
Dugaru said:
After buying my -9A, I eventually noticed my airbox had no baffling “tube” connecting it to the scoop in the bottom of the cowl. I dutifully installed baffling per the plans. Used flexible silicone baffling material but it still made cowl removal a pain. Eventually the baffling got damaged during a particularly ham handed cowl removal at a remote location. I removed it and flew home, figuring it had flown fine for years without it.

Key discovery, after a before/after analysis using engine analyzer data and the Savvy website: no discernible difference in any measured parameter with or without the baffling. In my carbureted plane, at least, it seems to be overkill. Possibly something the previous owner had already figured out. :ROFLMAO: Cowl removal is much easier without it.
Click to expand...

I doubt your analysis included any cowl pressure data.
 
OH! Interesting thought. It could be that inadequate baffling around the carb box over-pressurizes the low pressure area. Hmmmmm.
 
StuBob said:
OH! Interesting thought. It could be that inadequate baffling around the carb box over-pressurizes the low pressure area. Hmmmmm.
Click to expand...
Depends on exit area. If the exit is large enough, the unsealed airbox inlet probably wouldn't make much difference.
 
DanH said:
Depends on exit area. If the exit is large enough, the unsealed airbox inlet probably wouldn't make much difference.
Click to expand...
And ISTM that one could watch CHTs and know whether the pressure differential was adversely affected.

I’m kind of interested in trimming the baffle back a little and seeing if that makes an operational difference, and if it makes a difference in ease of maintenance.
 
I use the step ladder as a wedge and put a thick foam sheet between the step ladder and the lower cowl to keep it in place. This is a really stable position and it allows me to fit the front cowl inlet and not worry about it moving.
 

Attachments

  • IMG_0711.JPG
    IMG_0711.JPG
    590.1 KB · Views: 60
On my -7 I tape the front of the gear leg fairings to minimize scuffing and then sit on my folding creeper, the ones that can either be a creeper or a rolling stool, and us hands to clear the I let ramps and then one hand on an inlet, one on the snorkel and a knee to balance and seems to work well, once you have “learned” the nuances after 4 times on/off.
 
uk_figs said:
This is one of the uses for my Harbor Freight hydraulic lift table, blanket on top and pump up to just under the snorkel, release the cowl sides and then try to drop the cowl straight down and clear the baffling on the intake and snorkel. I do tape the back of the spinner and prop blades (3 blade Catto). Still a pain but doable with one person and some 🤬 language. Very interesting comment about the flexible baffling around the airbox intake as I wonder without that there would also be some airflow through the lower cowling, would that help pull more upper cowling air through the cylinders or just add drag?
Figs
Click to expand...
I bought one of these HF lift tables following Figs advice in a previous thread and used it during my condition inspection and also for a Piet restoration project. All I've got to say is it's the best money I've spent in quite a while. A few pillows placed on the table hold the cowl in position while you raise it and fuss with the seals around the inlets. Also works a great on lifting the tail. Well worth the cost while saving my aging back. I highly recommend it.
 
Does it change the difficulty of removing the cowl if you use hinges or camlocs? I use camlocs. Never tried hinges. I remove all the camlocs except two on each side, then remove two on the left while holding the cowl in place with my other hand, work my way over to the right while holding the cowl, and then remove the last two. Then, I have both hands free to carefully lower the cowl. Also helps that I don't have a nosewheel.
 
I found my buddy’s cowling cradle pictures, but don’t know how to put a link here. Just search hhking. cfiidon posted the info about using binder clips and camjam caribiner things to lower the cowling. I can attest it makes the job easy. 😎
 
MED said:
I found my buddy’s cowling cradle pictures, but don’t know how to put a link here. Just search hhking...
Click to expand...

Here's HHKing:

Tip: Lower Cowl Installation by Yourself

I came up with this method of putting the lower cowl in place on my RV-8. Others have also supplied tips, but I wanted something that was small and lightweight to carry in the airplane. I envisioned having to replace the lower cowl on a windy ramp at night on an isolated ramp somewhere. The...
vansairforce.net vansairforce.net
 
I can remove the cowling by myself but t's a PITA to re-cowl my -9A (w/ camloks and plenum). The plenum does simplify the process, however. Rather than the hassle of lifts or cradles (just one more thing to store in my hangar), I just find another person...I only need them for a few minutes not including chat time. Failing that, line guys are always willing to help (gotta tip them though) or I grab a family member (my 10-y/o granddaughter is more expensive than the line guys because her assistance always includes a trip to Starbucks).
 
rv8ch said:
Does it change the difficulty of removing the cowl if you use hinges or camlocs? I use camlocs. Never tried hinges. I remove all the camlocs except two on each side, then remove two on the left while holding the cowl in place with my other hand, work my way over to the right while holding the cowl, and then remove the last two. Then, I have both hands free to carefully lower the cowl. Also helps that I don't have a nosewheel.
Click to expand...
It wouldn't make a difference as far as my OP problem goes. But I'm sure camlocs all around make it easier to put it all back together.
 
That HF hydraulic lift table is an absolute turn-on! I suspect it'll be useful when fooling with the cowling. But even if it isn't, it'll be good to place under the tail when it's elevated.
 
StuBob said:
And ISTM that one could watch CHTs and know whether the pressure differential was adversely affected.

I’m kind of interested in trimming the baffle back a little and seeing if that makes an operational difference, and if it makes a difference in ease of maintenance.
Click to expand...
My CHTs were unchanged after I removed the stuff entirely. Definitely made removing the cowl easier.
 
Dugaru said:
Your doubt is fully justified! What might measuring that reveal?
Click to expand...
It would define the change with more accuracy than a CHT snapshot.

Do note a possibility...perhaps the inconvenient airbox seal wasn't very good. If it wasn't actually sealing, removing it wouldn't make a difference.

Poor sealing may also result in a loss of dynamic pressure to the engine intake.

Dugaru said:
My CHTs were unchanged after I removed the stuff entirely.
Click to expand...
Which were?
 
DanH said:
It would define the change with more accuracy than a CHT snapshot.
Click to expand...
Not sure what you mean by “snapshot.”

CHTs have always been well within the Mike Busch & Lycoming acceptable range. Hottest one gets to 400 in cruise in the hottest part of the summer. Plenum seems to do a good job.
 
On my planes I use a round (like) artificial leather on which I cut a round hole in it. It also has a radial cut which separates it and allows it to put it around the spinner backplate. I sewed velcro on the separated ends to hold it in place on the plane.
So, when removing the cowl the leather is between the spinner and cowling and so protects both surfaces:

i7GakHWh.jpg
 
You must log in or register to reply here.