The Machine

Consider your relationship with your car. The familiarity you have of its quirks and idiosyncrasies. The tricks you do to get it started on a cold morning. That smell it makes when you turn on the heater. The way it tracks if you let go of the wheel on the highway. That grinding noise when you put it in reverse. Think of all the things—the little rattles and squeaks—that cue you to the health of your vehicle.

   Pilots have the same relationship to their planes, but to a more refined degree—a reflection of the complexity of the machine, the training and nature of pilots, and the environment in which planes operate. Which is to say, if something breaks while airborne, there’s no pulling over to the side of the road to sort things out.

   The process begins before you start the engine with the “walkaround,” a visual check of the aircraft and its essential components. This includes fuel and oil levels; freedom of movement of the flight controls; tire inflation; lights; a check of the engine compartment for oil leaks or drips, hose connections, fuel lines and spark plugs—really, anything obviously the matter. The walkaround is done methodically the same way every time. It is part of a series of checklists outlining each step of aircraft operation. For some reason (at least in the few planes I’ve flown), the walkaround is always done going in a counterclockwise movement around the plane. Why? I don’t know.

            After engine startup and before takeoff, there’s another series of checks—the run-up. Here you apply not-quite full power and check the oil temperature and pressure, engine speed and temperatures, the magnetos, apply carburetor heat (if necessary), check the propeller control, elevator trim, vacuum system (for gyroscopically controlled instruments), the doors, check again the fuel gauges and tank selector, as well as set the communication and navigation radios.

            Once airborne, pilots continually scan their engine instruments to check on the engine’s performance. The oil temperature and pressure. Fuel flow. Cylinder head and exhaust temperatures. Electrical output. They also rely on their own sense and experience to assess their plane’s health. Does the engine seem happiest when running at 2,400 rpms or 2,200 rpms? Do the cylinder head temperatures tend to level off around 320 degrees or 360 degrees? How many hours does the plane go before you need to add a quart of oil? Every plane has its peculiarities, even planes of the same type, and pilots learn to attune themselves to these traits, alert to anything amiss.

            Again, all of this is the result of training, not paranoia. Aircraft engines are remarkably reliable, designed to produce at or near full power continuously over the course of their useful life. My plane’s 250 horsepower Lycoming engine is rated to go 2,000 hours between overhauls. Given a cruise speed of 155 knots, that translates to 356,000 miles. How many automotive engines can claim that level of reliability?

            Nevertheless, it was an aviator who came up with the adage, “Anything that can go wrong will go wrong,” and it was an aviator flying at night in clouds who said, “Anything that can go wrong will go wrong—at the worst possible time.” It’s why at night that I always seem to hear a strange new sound coming from the engine, or an odd vibration through the control yoke.

            Last month, I was returning from a late afternoon flight to New Jersey. The sun was setting as I leveled off over a layer of clouds that covered northern New Jersey and metropolitan New York, and for a few moments I allowed myself to take in the beauty of the scene before me. Then I looked at my engine gauges and saw that my Number 1 cylinder was running cooler than usual—nothing huge, but noticeable—a good 35-40 degrees off where it tends to settle.

            I contemplated this for a few moments and tried to figure an explanation. The engine sounded fine and seemed to be performing normally. Perhaps one of the cylinder’s two spark plugs had fouled or gone bad. So I tried leaning the mixture to see if that cleared things. Nope. I then did a magneto check to see if by turning off the sparkplug the cylinder went cold. Nope.

            I continued to puzzle over the matter when it occurred to me that the Number 1 cylinder was the first cylinder behind the propeller, the first cylinder to be blasted by the air blowing by the airplane, and that maybe the difference could be explained by the fact that we were on the verge of winter, and that the cylinder’s colder temperature was the result of colder air hitting it. Maybe.

            Whatever the cause, I wasn’t going to resolve it in the air. By the same token, I concluded the situation didn’t warrant an emergency landing,  so I decided to continue to my home airport. I also took a photo of the readings on the engine gauge to show my mechanic. 

            By then the cloud deck below me had given way to clear air and the lights of the towns and cities of Connecticut stretching up to Rhode Island and southeastern Massachusetts. I might have enjoyed the view, but the temperature discrepancy continued to bother me.

            Being a firm believer in Murphy’s Law, I pulled up my sectional chart, which showed me all the airports both large and small along my route. For the next 30 minutes, I picked out the nearest field to me. Those that were dark but had pilot-controlled runway lighting I tuned to the frequency to turn on the runway lights. Those that had no lights I tried to pick out of the blackness where the airport was and determine the runway orientation. Just in case…

            Landing safely at home, the next day I took my story and the gauge readings to my mechanic. He agreed the temperature difference was a little unusual, but had no explanation of why. “Keep an eye on it,” he said. Besides, the plane was going in for its annual inspection the next week.

            The day after pulling my plane into his hangar for annual, my mechanic called me.

            “Bad news,” he said. “I found pieces of metal in the oil screen.” He explained my engine needed to be removed, shipped to an engine shop for disassembly and inspection, and then rebuilt. My plane’s out of commission for three to four months.

            “But it’s a good thing we discovered it on the ground rather than you discovering it in the air. It might have been catastrophic.”

            Yes, I admitted with bittersweet relief, a very good thing.