May 9, 2002

What a morning for flying! The first weekend of May is regarded by many as the opening day of the summer flying season, and last Saturday was an incredible spring day. Winds were light, and after a chilly start, the temperatures became quite comfortable under bright sunshine. I knew that my only flying for the weekend would be "on the payroll", so I made the best of my flight home from Syracuse.

The Company plane is supposed to be flown as though it is on tracks. To listen to the corporate and regulatory bigwigs, you could believe that airplanes are required to move through the sky like prisoners in a road gang. One after another in perfect row, cadence, and spacing. At work, I am happy to pretend that this sort of thing is normal, but until birds fly that way, I will always regard commercial aviation to be a bit unnatural.

I chose to fly at 4000 feet, the lowest assignable altitude for the trip, a selection based on sightseeing. I let my course undulate a bit, as dictated by the sights offered by the greening earth below. For a few minutes I traced little figure- eights with on the scenery ahead with the nose of the airplane. Little turns, climbs and descents that pass unnoticed on the big picture of the controller's radar.

It would have been a great morning to jump into my little red airplane and go find the guys at breakfast, but the plane caught a case of the wheeze two weeks ago. I have spent thousands of hours flying behind the small engines made by Continental, and none has ever let me down, but part of that good fortune is borne of the fact that I don't trust them. Before each flight I pull the propeller through several compression strokes, feeling each one and comparing each to the others. I listen for air that might hiss past an exhaust valve.

This simple test, plus other common- sense observations can go a long way in preventing sudden engine trouble. These are basic gasoline engines, and are in most ways no more sophisticated than the farm tractor engines of the late 30s. The fuel comes in through a simple updraft carburetor and the mixture is fired by magnetos just like the old days. The engine is simple enough that it talks to people, not computers, and a lot of trouble can be prevented with a little bit of attention.

Something that I learned a long time ago is to respect the exhaust valves of these engines. Literally bathed in fire when they are open, their life is difficult enough even when things are running right. The edges, the thinnest part of the valve, are cooled by dissipating the heat into the cylinder head during the time that the valve is closed. If a valve is allowed to leak, this heat transfer is interrupted and the valve will not cool effectively or evenly. The extra thermal stress eventually leads to a complete failure of the valve; its head breaks loose and the airplane becomes a glider.

The engines are laid out like the familiar and classic Volkswagen engines, where the cylinder assemblies are bolted to both sides of a central crankcase. I spent the best part of Saturday afternoon in the hangar with my airplane, checking things over, making sure that there were no other problems, and removing the cylinder with the leaky valve. It will have to be taken to someone who has the tools to resurface the valve and its seat, after the worn out valve guide is replaced.

While all my friends no doubt went flying, I gradually trampled the grass around my airplane into mud as I worked. I was isolated from the fun part of aviation but the world continued to turn despite my fate. Planes passed overhead but never saw me, castaway and alone on a small uncharted hilltop airport, far from the comforts of a fly-in restaurant.

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