Joe, great write up. Glad everything worked out in getting her on the ground. Your observations and reflections on what you had seen is as valuable information as I have seen on the KRNet. Good stuff Joe, get her back flying soon.
Dana Overall 1999 & 2000 National KR Gathering host Richmond, KY i39 RV-7 slider "Black Magic" Flying..well sorta, useta, kinda Barrett Precision O 360 A1A Hartzell C2YR-1BFP/F7497-2 http://rvflying.tripod.com/blackmagic.jpg http://www.youtube.com/watch?v=MMi05-WU2D0#GU5U2spHI_4 http://rvflying.tripod.com do not archive > From: joe.kr2s.buil...@juno.com > Date: Tue, 15 Jun 2010 23:31:24 +0000 > To: kr...@mylist.net; corvaircr...@mylist.net > CC: > Subject: KR> dropped seat up-date > > Good Morning Guys, > As most of you may know On my way to landing at the Virginia Regional Fly Inn > I suffered a engine malfunction. While the engine was indeed running rough, I > was able to quickly identify the cylinder that was in-distress and made > several tries at correcting the problem from cockpit controls by varying > throttle and mixture. I was still producing power and was able to accelerate > and climb. I made the decision to land normal nd not screw u the pattern that > was very busy. I was able to taxi to a parking spot and shut down all with > out anyone else being aware that I had a issue. > On the ground it was determined that there was no compression at all in > the center passenger side cylinder. > I made the decision to truck N357CJ home. > This brings us to the forensics of the problem. I did a static leak > test and found it to be a full leak thru the intake. I also could see the > valve seat thru the spark plug hole. I pulled the head off and was able to > see exactly what was suspected. The valve seat had come completely out and > turned some what sideways and the valve had beat the seat into the head. As i > understand this is something that happens to the corvair occasionally. > The most important information i am leading up to here are the signs > that I pretty much ignored that might have prevented as much damage and > certainly saved a $1000 in travel expenses. > A couple weeks before the trip to Virginia i had changed the spark > plugs. The actual event of the valve seat becoming loose may or may not have > happened either right before i changed plugs or the very next flight after. > In any case I did not notice the temperature change until the first flight > after changing the plugs. The front cylinder on the right bank had a higher > temp than normal by 20 to 30 deg. The middle cylinder head temp was lower by > 90 to 100 deg and the rear cylinder head temp was normal. I had put this > info out on the net and got a couple responses that I had not considered and > that was that I may have damaged the temp sensors. I had not thought that I > damaged them but became more nonchalant about the problem. The other thing > was that i had more trouble getting consistent exhaust temps. And in fact the > entire bank of temps would switch from one bank to the other as far as the > high exhaust temps with changes in throttle settings and even change when > sett at one setting for 3 or 4 minutes at a time. > I present this information for everyone else to learn from.. I have a > full set of instruments to draw information from. I did not properly process > the information I received from them. For those that do not have full sensors > I believe that you are putting yourself at a disadvantage to start with but > would give you an excuse for not realizing a problem. For the pilots that do > have full engine monitoring i would strongly encourage vigilance in > processing the information that is presented. I should have verified the > probes were indeed faulty or not. Then I would have known that something was > amiss. I still may not have known what so I am saying now that if you > experience a low cylinder head temp that can not be changed by throttle > settings or mixture changes you should certainly consider that you may be on > the way to loosing a valve seat. > As a side note I burn 100ll all the time. when i had the heads off at > 280 hours there was a very thick build up of lead on the entire combustion > chamber. At this time there is over 200 hours on the cleaned up combustion > chamber. There is again a lead deposit but not near a bad. More like 20% as > much as it was 2 years ago. The difference is only that i have been using > Marvel Mystery Oil in the fuel. Not by any means a scientific test nor am I > encouraging the use. Merely stating that I am trying it and it seems to make > difference. The worst part of the lead is that it is attaching to the valves > and making deposits on the seats that probably keep them from sealing > completely at some point in time. > I'm not sure how I am going to have the head problem resolved yet or > when i will get to give a flight report again but it won't be that long til > I'm free to time travel again. > Joe Horton, Coopersburg Pa. > > > > ____________________________________________________________ > Penny Stock Jumping 2000% > Sign up to the #1 voted penny stock newsletter for free today! > http://thirdpartyoffers.juno.com/TGL3141/4c180d9cbf4fc403282st02duc > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html _________________________________________________________________ The New Busy is not the too busy. 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