Erik,
I could not see any visible damage to the exhuast
valve on my #5 when it ate a screw but when tested by the cylinder shop the
exhuast valve was leaking due to damage from the screw exiting. Even if the
valve was fine the shop ground off all the burrs and high points caused by the
screw to prevent them from becoming a source of heat that causes the mixture to
ignite early. Preignition will quickly ruin your day and the engine.
Maybe I missed it. Did your friend pull #2
cyl and have it checked and cleaned up? I not an A&P, but I would recommend
it. I did the R&R myself for the cost of a few gaskets. The local shop
charges a flat $300 for the job. That, plus the cost of any cylinder work is
cheap insurance, in my humble opinion.
Your fix sounds like a good approach. My
Ram Air is still off the plane while I decided how to not have a repeat
episode. Your fix sounds like a good one.
Good luck
Paul Bricker
N63PB
From: Lancair Mailing
List [mailto:lml@lancaironline.net] On Behalf
Of asw20747@aol.com
Sent: Tuesday, August 28, 2007
10:43 AM
To: lml@lancaironline.net
Subject: [LML] Fwd: Ram Air Valve
- More Loose Screws!!
-----Original
Message-----
From: asw20747@aol.com
To: lml-digest@lancaironline.net
Sent: Tue, 28 Aug 2007 9:18 am
Subject: Ram Air Valve - More Loose Screws!!
Just a heads up the group......
The (2) 6-32 Allen Cap Screws that hold the butterfly ram air valve on the
Legacy can and DO come loose!!! (see previous post with an ES also)
This didn't happen to me directly but another Legacy that I'm well aware of. We
have been checking these screws, with a small flashlight and a mirror inserted
in the tube opening, about every other flight. On this particular Legacy,
the screws looked to be fully seated with ALL the threads showing on the back
side and then on a subsequent check, 3 days (2 flights) later, we found one
screw missing and the other one half way backed out. When they come
loose, it apparently happens pretty fast!!!
Borescope inspection revealed that this screw ended up in the number #2
cyl and bounced around a bit without doing much damage before it exited......
LUCKY!!!
The next occurrence may NOT be so lucky.
This is what we did for a fix. NOT a recommendation necessarily..... just
what we did.
* Took the inlet tube/valve off the airplane
* Made a long extraction/insertion tool with a 7/64 ball driver and a
"T" handle at one end to remove the screws (one at a time if you
still have them both!)
* Replace the 6-32 (3/8" long) with high quality 6-32 (1/2")
long Allen Cap Screws
* To hold the screws in place on the end of the ball driver we used a
small piece of plastic tygon tubing inserted over the end of the ball driver
* Put the new screw in, this can take a while but can be done with
patience.
* After the screw is inserted, backed it out so maximum threads were
showing
* With a LONG Q-tip inserted down the tube, spread Loctite #267 (EXTRA
high strength RED) over the backed-out threads and then immedaitely tightened
it down
Notes- we found it was best to get both new screws in place BEFORE tightening
with Loctite. The reason we didn't put the Locktite on the threads FIRST,
and then insert the screws, is that the Locktite 267 with its integrated
primer, was actually starting to dry BEFORE we could get the screw started.
Our test samples showed, one thing. If we EVER need to get those screws
out..... WE CAN"T!!!!
I don't know if Lancair has yet come up with a comprehensive list of who has
what valve and which were prepared correctly, but I don't think this is
anything to fool around with.
Prior to this event, we thought that by keeping an eye on the screws, we would
be OK until we heard from Lancair. THAT
IS NOT THE CASE!!!
Hope this helps.
Best regards,
Erik Larson
Legacy
N74FX
ASW20747@aol.com
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