A stuck valve leads to an impromptu skydiving flight

“You gotta let me pay you for your time and materials,” I said to Art and Goren (not their real names), the two ag pilots who showed us how to free up a stuck valve on the 0-200 Continental engine of our Cessna 150. They simply refused payment of any kind. Then Art said, “Well, I would like to jump from a 150.”

Jump, like parachute jump? That is exactly what he meant.

We had landed two days earlier at Monroe City, Missouri, just to buy gas and continue on to Wisconsin. The exhaust valve on the number four cylinder was stuck again. I say again because we had this problem frequently. Before starting the engine we always rotated the prop to feel for compression. The previous owner was a mechanic and taught us to do this. Rotating the prop leads to a build up of compression in each cylinder, but when a valve is stuck, the feeling is slack. This is caused by the valve being stuck in the open position.

Stuck valve
Those little valves can be a big problem.

Before this flight, this had only happened at our home airport and help was available. Now we were attempting our first long flight out of Texas. It was July 1993, the year of the big flood of the Mississippi and Missouri Rivers. Finding a mechanic in that area would be difficult.

“We can show you what to do, but you will have to do it,” said Art.

The two pilots had many hours of work scheduled for their AgCat and were obviously busy. We saw no choice but to get the job started and then maybe a mechanic could be found. Art and Goren would tell us what to do in between their work cycles of fueling and loading the AgCat. This happened about every fifty minutes. They would land and take a break by our plane then tell us what to do next. It seemed like each task had the right kind of time span, e.g., take off the cowling, take off the valve cover, use these special wrenches to unbolt the cylinder, etc.

It was hot and humid, but there was no threat of rain. This was good because engine parts were carefully laid out on the tarmac in the order they came off the plane. Art explained that very likely the valve guides had to be reamed out and polished, assuming there was no parts failure. I wasn’t totally without experience since I had torn down and rebuilt a VW Beetle engine in the past. In some ways, the 0-200 looks the same, i.e., air cooled, flat opposed cylinders, etc. Yet, we are talking about getting airborne not driving down the highway where we can pull over if there is a problem.

By 3 pm, we identified the stuck exhaust valve, cleaned its valve guide, and started re-assembly. I wasn’t sure that all the parts would go back correctly, but Art and Goren double-checked our work. Finally, we rotated the prop and could feel compression in all four cylinders. After my wife and I replaced the cowling is when I offered to pay for their time and materials. Though Art said no, he did say: “I have close to 100 jumps from different kinds of planes, but never a Cessna 150. If you are game, let’s give it a shot.”

How could I say no? Also, I wanted to fly the plane around the airport to test our work before continuing on. Art disappeared into the AgCat hangar to get his gear, which I assumed was just the parachute.

He emerged in a Day-Glo yellow jump suit along with a white helmet. The parachute package seemed really small to me, about the size of a folded blanket. This made ingress and egress of the small cockpit easier, but it still felt crowded with the two of us as I started the engine. Pre-flight and mag test were normal; we taxied out.

Cessna 150
The Cessna 150 is not what most people think of when they hear “jump plane.”

“Take it to about 4,000 feet and put me over the airport,” said Art.

I put the plane into a slow climb and wondered how this was going to work. Obviously, I had never experienced someone jumping out of our plane. I queried him about what I should do.

“When we get into position, go into slow flight so I can open the door. When I push off, don’t let me get stuck, just push me if I do,” Art said.

Just push him out the door, I thought. That might be easier said than done. But it wasn’t even necessary. At 4,000, Art pushed the door open against the airstream and put one foot on the strut. He looked back at me and smiled, then was gone. I was able to get the door latched and then started a slow bank to see where he was. The chute was bright red and white. Art was circling and maneuvering toward an X he had placed on the grass near the AgCat hangar. I kept in the bank and watched him land within a few feet of his target.

After landing the 150, I congratulated him on his expertise. We thanked him again for all their help and took off for Platteville, Wisconsin. That wasn’t the end of our stuck exhaust valve, by the way. We interviewed countless 0-200 Continental engine owners for comparative data. We tried Marvel Mystery Oil and many other additives. We learned how to pull the valve cover, tie safety wire on the valve and lower it into the cylinder. Then, we could clean and oil the guide. Very carefully we pulled the valve back up and into position to attach the keeper. This is not the best way to deal with the problem but if you are forced down in the middle of the field being sprayed, you learn how to repair your AgCat. The occasional Cessna 150 is even simpler.

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