Dec 2010/Jan 2011 Annual

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cjensen
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Dec 2010/Jan 2011 Annual

Post by cjensen »

I decided to annual my 7 a bit early to set up future winter annuals so I'm not down for an extended time in the summer...so, I put up a page on my website that will get updated each day (already has three entries) as I progress thru it...

http://www.chadandbrittne.com/December% ... annual.htm

The first thing I want to point out is something that matches exactly what Brian (Chesteen) ended up with after the first several hours...cracked baffling at the oil cooler. I noticed mine was cracked about a half inch after the 5 hour oil change, but between then and hour 25, it had progressed to about two inches. From 25-30, it ended up like this...

Image

I'd say another hour or two, and the oil cooler would've been dangling off the back! :o I should've fixed it at the 25 hour oil change, but for reasons I can't remember, I didn't.

The other big squawk (I have several small issues to address, but only two big ones), and it's not really even a squawk, technically...the compression on cylinder 3 was "only" 62/80. All the others were 72+. This raised my eyebrow, and even tho it is within Lycoming limits, I wanted to investigate further. After a day and a half looking at it with a borescope (every A&P in the shop had a look), we determined that it was not a burned valve, and that it was probably some carbon built up on the seat. That may still be the case, but we found the hydraulic lifter for the exhaust valve had some "gunk" in it that wasn't allowing the valve to seat fully. After that time consuming journey, we did a cold compression check, and it's up to 68 pounds, which should translate to somewhere back in the 70's when hot. The diagnosis is to fly it 5-10 hours, and check it again.

Just an fyi...if ya care to know what I'm doing instead of flying for a couple of weeks... :wink:
Chad Jensen
Missing my RV-7...
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smithhb
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Post by smithhb »

Chad,

I had heard of others having the baffles crack so I reinforced mine like this. So far, after 165 hrs no problems...

Image

Image

Hope this helps![/img]
Bret Smith
9A Flying (N16BL)
Blue Ridge, GA
http://www.FlightInnovations.com
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cjensen
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Post by cjensen »

Great idea Bret...unfortunately it won't work with my plenum.

I'm thinking of using some AL angle down the side and thicker AL sheet to replace the broken piece...
Chad Jensen
Missing my RV-7...
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Spike
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Post by Spike »

Very interesting Chad. It really shows how vibrations and our brittle aluminum can interact. Thanx for showing us whats up.

Spike
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hydroguy2
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Post by hydroguy2 »

interesting, I would have thought the plenum would stabilize that area. I'll be taking a real close look at mine, plus I have an angle standoff for my cooler.
Brian
Townsend, MT

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painless
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Post by painless »

Chad, sorry to see this crack. There is another way I have seen guys use to prevent this. A support rod, or aluminum angle is attached to the engine lift point (the bolt and loop amidships of the engine) and then attached to the baffle upper outside corner where the cooler is mounted. Should work with your plenum. This would give your baffle more support and rigidity.

Chill'n in southern Cal...... Literally!!! Go Bucky.
Jeff Orear
RV6A N782P
Hatz Classic, Welding fuselage
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Peshtigo, WI

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Mike Balzer
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Post by Mike Balzer »

Chad,
some 5052-h32 aluminum would be less prone to cracking and maybe you could make a doubler out of .125 and rivet it to your baffle and stop drill the crack so it does not continue.

2024-t3 aluminum is brittle and when subject to vibration and stress will cause it to crack.

I also recommend adding Marvel Mystery Oil to your fuel at about 4-6 ounces per gallon on one tank and fly it. This will help bring up compression also. It helps remove the lead and carbon build up on the valve seats and cant hurt.

We did this on a friends o-235 that has little time left on it and it brought compression up to specs when it was well below specs before.

During compression test could you tell where the Loss was. EX: intake valve, exhaust valve or crankcase? This may help determine what the cause is.

Happy New Year,

Mike Balzer
It is better to be on the ground wishing you were in the air, then being in the air and wishing you were on the ground. N78MB

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cjensen
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Post by cjensen »

I'll post a pic of the baffle fix later tonight...

I may try the mystery oil. Heard good things about it.

It's out the exhaust valve for sure, less so now with the lifter cleared out. I'll fly it a few hours and recheck it.
Chad Jensen
Missing my RV-7...
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Wicked Stick
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Post by Wicked Stick »

Chad,

Get some .125 aluminum angle stock and fabricate two pieces like you see here below. One on each side. This worked out great for me and really makes it bullet proof. It should work fine with your plenum.

Also I noticed on your photo that you don't have the 3/4 brace down the side of the baffle either? Add one there too if you don't have it.
Image
Image
Dave "WS" Rogers
RV-8 (125 hrs & counting)
N173DR

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cjensen
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Post by cjensen »

Here's my fix for the oil cooler baffle crack. I didn't add another piece because the plenum does provide support for the baffle along the sides. The main concern is the vibration from the cooler...

Image
Chad Jensen
Missing my RV-7...
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Mike Balzer
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Post by Mike Balzer »

Nice work,
Looks like it will last forever now?


Happy New Year,

Mike
It is better to be on the ground wishing you were in the air, then being in the air and wishing you were on the ground. N78MB

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cjensen
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Post by cjensen »

That'd be nice, but I don't think I can count on that for sure! :)
Chad Jensen
Missing my RV-7...
Vertical Power support
920.216.3699
http://verticalpower.com

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