Having owned seven airplanes in the past 20 years, I can tell you that saving money on airplane ownership is a high priority. One of the areas I save on is maintenance. No, not by cutting corners or deferring things that need to be fixed — in fact, I've learned that the more you spend on preventive maintenance, the less it costs you, and the more reliable your airplane becomes. Rather, I've discovered that I can reduce the cost of ownership by thinking like a mechanic. For example, when I bought my present airplane, a Cessna 185, cylinder-head temperature indications were higher than they should have been. If you closed the cowl flaps in cruise, the CHT needle would climb right past the red line. Take an airplane to a mechanic with a problem like this, telling him, "The CHT is a little high; I'll be back tomorrow morning to pick it up," and you have just handed him a blank check.
There is a better way, and it involves becoming a part of the team that produces solutions for airplane problems. Here's how it works: Pretend that you are a mechanic who reads the squawk list provided by the owner of an airplane. The write-up reads "CHT high." What do you do?
When a mechanic gets a squawk like this, his first question is probably going to be "How high is it?" This may be followed by more questions such as, "Is the temperature high from startup to shutdown, or just in cruise? Are you running the cowl flaps open, trailed, or can you close them? Did this problem develop suddenly or has it crept up over time? What is the outside air temperature (OAT) when this problem shows up? How much time is on the engine? How is the compression? Is the temperature steady or intermittent; all flights or just some? Is the oil temperature also high? Has the CHT gauge ever been calibrated? Have you changed anything recently in the engine compartment? How long have you had this problem?"
In other words, the mechanic begins methodically troubleshooting with a series of questions designed to reveal a probable cause — then, with this new conjecture, develops a plan to investigate and prove or disprove that possibility. If you don't know the answers to the kinds of questions a mechanic might ask, you are probably in for some pretty expensive troubleshooting (at $40 to $75 an hour) or a test flight to verify the problem. This can be reduced by developing the mindset of a mechanic and beginning the question-and-answer process yourself.
By asking questions and providing answers to the mechanic, you become a part of the problem-solving team. Since you probably know the history of your airplane better than anyone — and certainly spend more time sitting in front of its many gauges and dials, listening to its normal and abnormal sounds — this should be easier for you than for a mechanic who might see your airplane only once or twice a year.
The best results are obtained with detailed written squawks and notes for the maintenance people. This prevents the missed squawk, "I don't remember your saying anything about the landing gear motor being noisy ..." and the unclear "but I thought you said you heard the thump only when you extended the flaps." Bottom line: the airplane doesn't get fixed. These notes and the squawk list should be complete, too. When most of us write up a squawk, we tend to write too little, as if we are being charged by the word. Remember, writers get paid by the word; mechanics get paid by the hour until the problem is identified and corrected.
Typical write-ups that frustrate mechanics are: "CHT inop" or "Nose gear light intermittent." But those two squawks can be improved by telling the mechanic how the CHT failed, when, and if it was intermittent before going west. With the nose gear light problem, you might note what percentage of the time it is intermittent, if it occurs only at high extensions speeds, or if the light eventually shines steady when the speed is reduced or when electrical load is off the system. Improving the quality of your write-up only improves the possibility of the squawk's being eliminated.
A good place to start your questions might be with the age-old journalistic standbys: who, what, where, when, why, and how. Then you might expand that knowledge-gathering process with some of that dazzling system knowledge that you have gleaned from studying the pilot's operating handbook, combined with your experience in the saddle. Better yet, get the service and parts manuals.
I've always had a great memory, but my retrieval system leaves a lot to be desired. So, I carry a small notebook in my airplane for these troubleshooting notes and recording squawks. The notebook takes the embarrassment out of those moments when the mechanic asks, "What's the CHT read in cruise with the cowl flaps closed, mixture leaned, and the OAT standard?" Blank stares only cost you money. A $2 notebook can save you from $100-an-hour test flights or $75-an-hour troubleshooting time with your mechanic.
Membership on this problem-solving team is welcomed by most mechanics because it helps them to reduce the dead ends that they may try along the road to solving your problem, thus reducing their work load. It also reduces your bill; and there are few things most mechanics would rather avoid than presenting you with a bill that they know you'll choke on, because of cost incurred by hours of needless trouble-shooting and parts replacement.
I did finally solve my CHT problem with help from several sharp mechanics, but only after replacing all baffle seals, cleaning and flow-checking the fuel injector nozzles, resetting the timing, replacing the CHT probe, and calibrating the gauge to the new probe — and a host of other little things. Throughout the year-long process, I was integral to the troubleshooting team; sure, I spent money on mechanics' time and parts, but in the end, the trouble turned out to be radio-frequency noise from the alternator. When the alternator was on in cruise, the CHT read high; when I turned it off (after first shutting down the radio master and most other high-load electrical items), the temperature dropped back to normal. Not one of the many mechanics who had helped me had ever heard of this happening. We all learned something. A noise filter installed in the alternator output lead solved the problem.
This could have been an extremely expensive squawk to ferret out and fix (instead of just very expensive), but the cost was undoubtedly reduced by my participation. Want to get your airplane fixed and back in the air in minimum time for the fewest dollars? Learn to think like a mechanic.
