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Seen at Walt's

DeltaRomeo

doug reeves: unfluencer
Staff member
He sent me this today.

IMG_1079.jpeg
click to enlarge
 
Yeh, ugly... I've rebuilt 3 FABs that were destroyed this way. All had black gooey paste under the filter that acted like wet sand paper eating through the fiberglass. The owners were excessively priming before starting, the excess fuel mixed with dust & dirt or whatever to form this paste on the floor of the FAB & well, this happens.
 
There are a few oddities there...... breather looks odd...

Never a shortage of "first time I've seen that" comments workin on RV's!

And I've seen plenty of worn airboxes but never one where the filter was hanging out the bottom :eek:
 
Ya think this could be an intake leak?
(just uploaded from my phone.. wow!)
 

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Great info - check under the cowl

These posts are really interesting and very helpful, at least for me.

One thing I'm convinced of is that I need to get very good at removing and installing my cowl. It's easy to do, but I'm worried about damage to my paint. What I do now is use a lot of "low tack" painters tape on the edges to protect the paint. Perhaps if I get more experience removing and installing the cowl I won't need it.
 
Mine Also

This was starting to happen to the air filter holder. I epoxied a piece of aluminium to the bottom of the air filter holder. This had to go unseen for a while to get that bad. If i was building, I would install the piece of aluminum from the beginning.
 
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This was starting to happen to the air filter holder. I epoxied a piece of aluminium to the bottom of the air filter holder. This had to go unseen for a while to get that bad. If i was building, I would install the piece of aluminum from the beginning.

A better choice would be to lay up a layer of Kevlar on the bottom.
 
Thanks Walt. I learn a lot from these discrepancies....how much longer till I get my A&P sign off?
 
That first picture is of a new "quick change access panel" for air filters :D. Still in the test phase.:rolleyes:

Seriously, I'm on my third FAB 360 air box but never because of that problem. Mine have been cracks in the aluminum base plate just aft of the carburetor. I keep a spare air box now so the repair won't slow me down.

Chris
 
That first picture is of a new "quick change access panel" for air filters :D. Still in the test phase.:rolleyes:

Seriously, I'm on my third FAB 360 air box but never because of that problem. Mine have been cracks in the aluminum base plate just aft of the carburetor. I keep a spare air box now so the repair won't slow me down.

Chris

Chris, I eliminated that problem with Increased To .090 Thickness, 2024 Aluminum With 45 Degree Linear Brace From Carb To Front Of Air Box (no more mount cracks)
 
A better choice would be to lay up a layer of Kevlar on the bottom.

This is exactly what I did a couple hundred hours ago. Very little sign of wear as yet, but we'll see. I'd re-glassed the bottom a couple times before, but it didn't last long, maybe 5-600 hours. That filter is moving with each pressure pulse I suspect.
 
Chris, I eliminated that problem with Increased To .090 Thickness, 2024 Aluminum With 45 Degree Linear Brace From Carb To Front Of Air Box (no more mount cracks)

Thanks Tracy. I was going to increase the thickness of the aluminum when I realized it was already .064 and figured if that is going to crack then anything might. But I'll give that a try next time, especially the "brace" -- that's probably the key, like the one I use to stabilize the engine baffles near the oil cooler.

Chris
 
Thanks Tracy. I was going to increase the thickness of the aluminum when I realized it was already .064 and figured if that is going to crack then anything might. But I'll give that a try next time, especially the "brace" -- that's probably the key, like the one I use to stabilize the engine baffles near the oil cooler.

Chris

The brace does appear to work Chris - I have them on all of our planes, and once installed, we haven’t had a cracked plate since.
 
The brace does appear to work Chris - I have them on all of our planes, and once installed, we haven’t had a cracked plate since.

I just fabricated & installed a 0.063 top plate as part of my AFP injection conversion. The original plate had a large crack in it. Sounds like I now need to add that brace. Does anyone have a picture? I'm a visual learner. :)
 
Oh, yes it can. I watched an owner remove a filter, clean & re-oil it and put it all back together. 2 months later after a major trip, he came in for an oil change & found his filter trying to escape, not near as severe as OP's example, but if given a few more hours would have been as ugly. The owner commented after the fact that there was a ring groove in the bottom of the FAB but didn't connect it's importance.
 
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