Joseph E. (Jeb) Burnside
A Jug In Time
On April 5, 2003, after a cruise climb from 8,000 to 9,000 feet MSL on the return flight from my annual pilgrimage to Sun 'n Fun in Lakeland, Fla., my airplane's engine suffered a partial failure just a few miles southwest of Jacksonville, Fla. I didn't know it at the time, but the #5 cylinder cracked near the intake valve. This apparently allowed the intake valve seat to loosen and lose position. Once this happened, the valve repeatedly slammed into the out-of-position seat, breaking itself into at least five pieces.
This was a pretty strong indication I was finished flying for the day.
We (I had two friends with me, both of whom are pilots) declared an emergency and landed at the nearest airport (Cecil Field, a former Naval Air Station). Once we cleaned the three seats, we set about the task of finding the problem, fixing it and getting the airplane back home.
Below are some images of the cylinder, piston and pieces of the valve. See further below for the rest of the story.
Click any image to view a larger version and use your browser's "Back" button to return...
 The engine with the #5 cylinder and alternator removed. A new piston is already installed, replacing the damaged one |
 Working on the airplane in the hangar at Cecil Field, Jacksonville, Fla. That's Lee Stikeleather, my IA, aka "The Man In Black." All of the people at Cecil Field (VQQ) were extremely helpful and supportive. I can't say enough about their attitude. Best place to land with an emergency I've ever found... |
 A close-up view of the damaged cylinder. The offending intake valve is the one on the right... |
 Another view, with the damaged piston partially viewable in the upper right. |
 The damaged piston. |
 The broken pieces of the valve. |
|
|
|
To get the airplane back home to Manassas, Va. (HEF), we procured a used cylinder and new piston/rings, etc. Lee drove down to Jacksonville to get the engine repaired. When he hung the used jug, Lee pulled the intake piping on the right side, looked all through it, etc. He also looked into the balance tube, as well as into the exhaust system. Since the flame cone on the right muffler was missing, we figured the valve pieces had departed via the exhaust system. There was no discernable damage to the exhaust valve and we did not attempt to pull it from the jug.
After replacing the jug and conducting a ground run-up to full power, Lee pronounced the engine good to go. To demonstrate his confidence, he rode along when I did the first test flight. Shortly after taking off and establishing a "loiter" pattern (how one can be loitering at 160 KIAS and 2,000 feet AGL is another story...), I pulled the mixture back to a lean-of-peak-EGT condition. A few moments later, I felt and heard the engine stumble. Figuring I leaned too far, I went ahead and enrichened the mixture. After a couple of minutes, the engine stumbled again. Needing no further encouragement, I promptly landed.
Lee and I tore into the engine, especially the fuel system and the spark plugs. Finding nothing wrong, we took off again. Sure enough, the engine repeatedly stumbled. This time, we noticed dropping EGT values on both the #5 (the replaced jug) and the #3 cylinders when the engine stumbled. The behavior was simultaneous and repeatable. We promptly landed again.
After tearing out our hair and calling anyone we could think of, we decided the problem was the used jug. We pulled it, the intake, etc., as well as the lifters, thinking it *had* to be a valve problem. Could not find a damn thing -- everything was as it should be. We pulled the air filter and looked down through it and the servo to the wye-shaped intake tubes. Nothing.
Then we happened to glance at the balance tube. Two pieces of the old #5's intake valve were barely visible. Also, there was some very fine aluminum alloy powder in the tube. Closer investigation revealed at least one of the pieces was loose in the tube and free to flap around and, inevitably, restrict airflow through the tube and, then, to the #5 jug and on down- (up- ?) stream to the #3 jug. Eureka!
Of course, getting the blasted things out was easier said than done. Two were wedged in pretty tight, having deformed the tube -- there's a *lot* of air moving around in that tube. On the Bonanza, the tube cannot be removed without at least raising the front of the engine out of its mounts. Not easy to do in the field, but we were getting ready to go buy a crane and had already located a new tube locally.
To make a long story short, Lee managed to fish the pieces out of the tube with some curved needle-nose pliers, a homemade "swab" comprised of twisted safety wire and a shop rag -- plus some elbow grease and appropriate language. We removed four pieces of the valve from the balance tube and were able to match them against what remained in the cylinder.
After a test flight, plus some "I Follow Roads" work to get the plane to my mother's home in Georgia, we flew it home to Manassas. Smooth flights, no issues.
A couple of months later, the engine was completely overhauled to new specifications, including Millennium cylinders. I now have more than 500 hours on the overhauled engine, with no problems whatsoever.
Moral of the story? Don't presume all those valve pieces departed in the same direction as you would like and check the intake system *thoroughly,* all of the intake system...
All images taken with a Nikon Coolpix 950
April 18, 2003
Copyright © Joseph E. (Jeb) Burnside. 2009. All rights reserved.
