Baffling folding back

[markejackson02]

Have a relatively new engine in the plane (77 201). Before every flight I get the baffling aligned correctly. After every flight the portion at the top of the cowling over the rear cylinders is folded back. Only way I can keep the temp reasonable is to fly with open cowl flaps.

I am leaning towards fabricating metal braces, drilling out the baffling rivets, and riveting there in place holding the baffling forward.

Has anyone else had this issue? I tried putting rivets through the silicon baffling and it worked at the corners but not behind the rear cylinders.

Mark Jackson

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[Guest]

I would suggest that the baffle tapes are too short or too thin which allows the air pressure to fold then backward.

Clarence

[jetdriven]

We had that problem. The gap between the cowl and the metal rear baffle is too great. What fixed it was two 1.5"x3" pieces of .032 aluminum riveted right to the silicone baffle material. It then couldn't roll under the cowl. I'll look for a picture.

[markejackson02]

We had that problem. The gap between the cowl and the metal rear baffle is too great. What fixed it was two 1.5"x3" pieces of .032 aluminum riveted right to the silicone baffle material. It then couldn't roll under the cowl. I'll look for a picture.

 

So riveted to the top of the baffling and then folded forward.  Makes sense.  I have a fair amount of 0.032 lying around from the RV-8.  My give that a shot.

 

Thanks very much,

[KSMooniac]

My '77 didn't need any fixes like that FWIW.  I replaced the OEM stuff with silicone soon after I got the plane and had no issues with it afterwards.

[jetdriven]

No, a doubler plate riveted about a half inch above the airplane metal baffling. It is only riveted to the baffle seal material to make it stiff. It makes the silicone baffle material stiff, so it can't roll under the cowl.

[markejackson02]

I installed three fasteners in the baffling material.  They are aluminum screw post fasteners from the PMA department at Lowe's.  Put one at each corner of the baffling and one over the center of the engine where the two baffle pieces meet.  Took two flights to get it right, the first time I installed it near the top of the baffling, and the second I installed it about 1/2" north of where the baffling meets the cowl.  Cylinder temps were 30-40 degrees cooler.

 

My mechanic stopped by while I was working on it.  He recommended two things - first trimming some off the baffling material.  When installed the material is too long and needs to be trimmed to fit.  Second was in the event of continued issue to put a piece of sheet metal on to raise the back baffling by 1/2" (Jetdriven's solution.)  

 

Hopefully this will cure it.

[jetdriven]

My solution was to rivet aluminum to the silicone baffle material only. Although I would guess that raising the top of the metal baffle along the rear may fix the problem also.

[FloridaMan]

I had the same problem. My solution was to take a 1/2x1/2 inch piece of foam insulation glued to the inside of the top of the cowling with red RTV. 

[Cruiser]

get some nylon cable ties, the wide ones long enough to be pushed up from under the back of the baffling material but in front of the metal base part the baffling is riveted to. Let the pointy end of the nylon cable ties stick up above the baffle material two or three inches. Place a cable tie or two of them between the rivet point to stiffen the baffling against the top cowl. The baffle material to metal base overlap should be tight enough to hold the cable ties in place just by the pressure. When you put the cowling on, place the back of the cowling first and roll it forward so it presses the nylon cable ties against the back of the baffle material and folding forward toward the prop.

I guarantee the baffle material will not fold back under the top cowl.

[helitim]

Mark,

If you still have heating issues after repairing the baffles, consider the oil cooler. While mine was down for engine repairs, I sent it down south and had a cooler flush/overhaul done. Came back like new and made a significant difference in operating temp. Hopefully the baffle repair will fix it.

Tim

[markejackson02]

Still having cooling issues with #4.  I have worked on the baffling and have gotten it working except for these little kinks.  Trying to figure out how to get rid of these.  I still can't keep #4 < 420 in cruise with the cowl flaps closed.

Any thoughts on how to get rid of the kinks?

 

[N201MKTurbo]

Cut darts in the baffle material.

[Bob_Belville]

Bob Kromer told us last weekend that they (Mooney Test Pilots) found that cruising with cowl flaps partially open was actually faster than closed. He further suggested rigging the cowl flaps to be 1" open when in the closed position, the exit cross section is just not adequate. I can imagine that there will be less pressure on the baffle seals with cowl flaps open. Faster, cooler... what's not to like? (I know his comments apply to "vintage" and confirm my own experience, I'm not positive about Js which have better balanced cooling.

[EDNR-Cruiser]

That might be true if you still fly the old dog-house style cowling, which was a real air-brake at that time...
If you have a modern cowling installed, it is contra-productive and my original 1966 POH mentions a max speed for cowl-flaps extended...

[jetdriven]

Still having cooling issues with #4.  I have worked on the baffling and have gotten it working except for these little kinks.  Trying to figure out how to get rid of these.  I still can't keep #4 < 420 in cruise with the cowl flaps closed.

Any thoughts on how to get rid of the kinks?

 

remove the oil cooler ramp baffle.  I did. 

[Bob_Belville]

That might be true if you still fly the old dog-house style cowling, which was a real air-brake at that time...
If you have a modern cowling installed, it is contra-productive and my original 1966 POH mentions a max speed for cowl-flaps extended...

Nope. I have a 201 style cowl and baffles. But I do have vintage cowl flaps which are smaller than 201.

http://mooneyspace.com/gallery/image/33685-replace-engine-baffle-seals/

http://mooneyspace.com/gallery/image/36717-led-lights-wide-angle-to-taxi-spot-for-landing/

[Andy95W]

Cut darts in the baffle material.

remove the oil cooler ramp baffle.  I did. 

+1

[Nemesis]

Perhaps the fastener shown in the upper right of the picture is in the wrong position. If there were no fastener there, maybe with air pressure under the cowl the seal material would be better able to stretch or extend a bit farther to the right in the photo (farther to the left side of the cowl) and would flatten the kinked areas. Or, if the fastener was pulling a bit farther to the right in the photo (pulling farther to the left side of the airplane), that also would take out the kinks.

I thought about writing to cut a slit along the center of the kink and that might let the kinked material edges to lay on top of each other. However, I think that is the wrong way to go and is partly destroying that nice new seal that you installed. Also, if it were cut, even if all of the other material correctly sealed against the top cowl, there is a good chance that the weakened material near the slits might fold back and you would still have the same problem.

So, I would opt to remove the fastener, stretch the seal material a bit farther to the right in the photo (farther to the left side of the airplane) and reinstall the fastener to a better position. Pulling the material farther to the right in the photo would remove the kinks.

Dave

[INA201]

My 3 and 4 cylinders would get into the low 400 range on occasion so I decided to redo the old baffling with silicone.  I have been having the same problem with the new baffling flipping back.  I was told to tighten up the baffling in the left and right sides to pull the baffling in so that it can't flip back.  If you look at the photo it does seem that it should cup inward vs sticking straight up.  I'm also seeing the ripple effect like jetdriven has.  I'm thinking that tightening it in the corners will fix both issues.  By the way, my CHTs are about 15-20 degrees cooler even with the flipping back ripple effect so I'm hoping tightening it up will subtract 15 more. Hopefully I will get to it this week and let you guys know. 

[jetdriven]

The cowl inflates in flight too and then the gap between the metal baffle and the cowl gets larger.  Carbon fiber stiffens it where it doesnt inflate. 

[Danb]

I decided not to rummage through tax returns and garbage financial data today then I tackled my baffling that folded down in a couple places, I suspect at my annual the MSC did not ensure the baffling was in the proper position,prior to putting on the cowling and presto it formed folded down. On a trip to West Palm last month I noticed my temps were up on some cylinders  so I looked at the baffles and yep.

I purchased the materials from Aircraft spruce last week and used the bad pieces as a template, then used a pop rivet thingie for the first time, geez worked great. Fit great looked great.

Took it for a test fly, they stayed  in place, plus the temps are back to normal, I can't believe I did it and it worked.

I attached the before pix and after pix. My Observation every time I bring it in for service I'll mention to the mechanic did he make sure the cowling is over the baffling properly, grab my flashlight and check it before leaving, It's a real shame having to look over the shoulders of the MSC mechanic but lesson learned.

[Bob_Belville]

Good for you Dan! I spend a lot of time tweaking baffle seals on my old E. Every little gap hurts CHTs.

[Danb]

Hard to believe Bob, my cht's were up by 30* on cyl2+4. plus +20 on the others. Amazing how much difference they make, I'm having a hard time believing a top MSC wouldn't put the cowling on correct 

[Bob_Belville]

1 minute ago, Danb said:

Hard to believe Bob, my cht's were up by 30* on cyl2+4. plus +20 on the others. Amazing how much difference they make, I'm having a hard time believing a top MSC wouldn't put the cowling on correct 

Bring it to AGL!  Maybe you and Marauder can work out your schedules and I'll take you home. We'll put Chris in the back of my E.