The Pilot’s Lounge #66:
What Is That Thing Inside The Cowling?

When you learned how to preflight an aircraft, you probably learned to check certain items for wear or breakage, but were you ever shown examples of what things looked like when they were worn too much? Or do you just guess? AVweb's Rick Durden found a class for pilots to learn enough so they don't have to guess.


Thanks to Professor Lisa Whittaker at Western Michigan University for providing much of the information in this column.

One of the frequent visitors to the pilots lounge, here at the virtual airport, is a pilot who has been flying for three or four years. He is conscientious, works on improving his skills and has fun flying airplanes. The other day I saw him preflighting the rental Arrow when I arrived at the airport. After I got out of my car, he walked up to me and very quietly asked if I’d look at the airplane for a moment. As we headed toward the nose, he looked around, as if to check to see if anyone could hear him, and then said, “The alternator belt doesn’t feel as tight as it usually is, and I frankly don’t know whether it’s OK or not. Would you check it?”I tugged on the belt and, while it wasn’t slack, it had more play than I thought was acceptable. Many years ago, I’d run a battery flat, at night, in a Lance, due to a loose belt, so I suggested that we take a walk over to the mechanic and see what he thought. Because the airplane was a part of the FBO’s rental fleet, Newt came right out, felt the belt and confirmed that it was too loose. It took him about 15 minutes to remedy the condition and my friend was on his way.

It wasn’t the first time that I’d noticed a pilot with a fair amount of experience puzzled about something observed on a preflight. We instructors teach students what pieces and parts of the airplane to gaze at on a preflight, but we don’t always have the tools or knowledge to teach them how to make the judgment calls about such things as acceptable wear, appropriate tension on belts or cables, what too look for in terms of chafing on electrical wires and cables or even explaining just what all that stuff inside the cowling is, and what it does. There are times I’ve been able to walk a student into the shop, pull out some used tires and demonstrate what was acceptable wear and when it was time for a replacement, but those times were the exception rather than the rule. I’ve also found it worthwhile to have students buy the local mechanic lunch in return for some conversation on how to decide when something is wrong with the airplane. Those talks usually expand into how to describe a squawk so that a maintenance technician can understand what the pilot observed and can work efficiently to fix it without having to play guessing games. The real problem is that — while such sessions are very valuable — only a few pilots get to take advantage of sitting down and learning from a mechanic, possibly because they are embarrassed to admit that lack of knowledge.The reality is that I, and many other instructors, have never found a good way of educating pilots about the mechanical workings of the airplanes we fly and how to decide when normal wear and tear has reached the point that the airplane should be refused.

Mechanical Seminar for Non-Mechanics

That was until recently. About two weeks ago I learned about a seminar, now in its third year, at Western Michigan University’s College of Aviation that is offered to provide information to help pilots make an educated preflight inspection of an airplane. The workshop is organized by Lisa Whittaker. She is now an Assistant Professor in the College of Aviation and an instrument flight instructor who spent almost 20 years working in technical product support at several major aircraft manufacturers. The local chapters of the Professional Aviation Maintenance Association (PAMA) and Women In Aviation International (WAI) help out with the workshops by recruiting students, creating handouts, leading the groups and providing instruction at the individual stations that are set up for hands-on work. Professor Whittaker’s background in the maintenance field — combined with her experience as a flight instructor — has given her a good understanding of what pilots should know about the workings of their airplanes without trying to turn them into A&Ps. PAMA members play a significant role in the workshop; at the very least, having pilots get the benefit of listening to, learning from, and talking with aviation maintenance professionals is a very positive event. It is also consistent with my opinion that the more interaction between pilots and mechanics, the better.The seminar runs from 9 on a Saturday morning until 3 in the afternoon, so the students can get out in time for a home football game. After all, following a day getting greasy in the hangar, what’s better than an ice-cold seat in a stadium?The seminar begins with an overview of the day’s activities and a safety briefing. The pilots are then assigned to groups of not more than 10 persons. They face a hangar containing several airplanes with the cowls removed and various portions of their guts exposed at a series of stations. The stations are arranged so that the pilots can easily gain access to engines, wiring, cables, batteries, and portions of the structure and flight controls. Electrical, hydraulic and engine laboratories that are part of the College of Aviation are nearby and become part of the stations through which the pilots rotate.

Multiple Stations, Hands-On Attention

One station covers preflight inspection of a fixed-gear, four-place single, including the FARs that are applicable along with a reminder that the pilot in command is the person ultimately responsible for determining whether the airplane is airworthy. A mechanic is there to help the pilots find discrepancies and make some suggestions as to how to preflight the airplane with an appropriately critical eye and make sure that no-go items are not overlooked. The instructor goes into how to read and check the aircraft maintenance records to make sure required inspections have been done (and pointing out that looking on the maintenance board at the FBO isn’t enough) as well as reviewing what inspections are required, what paperwork has to be in the airplane, lights required, and navigational equipment needed, along with the required checks for IFR. One of the areas stressed is what is legal and what isn’t with regard to inoperative equipment, including what can be disabled and tagged, versus what components on the aircraft equipment list must be in working order for the airplane to be considered airworthy. Fuel sampling is done and examples of fuel contamination shown along with pointing out that if four or five samples continue to show water contamination, there is probably serious contamination of the system that it may not be possible for the pilot to correct so it’s wise to get a mechanic involved because it may be necessary to drain and purge the system.

The engine lab gives pilots personal time with an uncowled engine and propeller. Having the entire powerplant exposed for all to see increases the understanding of just what is going on in the noisy part of the airplane. This helps explain how the parts of the engine work in conjunction with each other, what’s going on in areas one can’t see through the oil access door, the route the cooling air takes as it flows over the engine and need for proper installation of the cowling and baffling, as baffling is critical to engine cooling. Such basics as what to do if one sees evidence of an oil leak and what the oil on the dipstick should look like are covered, along with more sophisticated issues such as examples of oil contamination or oil breakdown that are unacceptable for flight. Pilots learn what a properly installed and tensioned alternator belt looks and feels like and examine examples of belts that are too loose or too badly worn for flight. They see cracks and damage to the exhaust system that can allow carbon monoxide in the cabin or that can lead to loss of portions of the system in flight and how to check it for security.At another station, the pilots get a close-up view of electrical systems, learning what to look for on a preflight and that there are some problems that a pilot can fix. One of the points that struck me as important was how to change the various light bulbs in and on the airplane (yes, I’ve heard most of the changing a light bulb jokes, and they are true). It is surprising to a lot of pilots that what should be a simple act is often not at all intuitive on an airplane. They also learn where fuses are kept and how to change them. The electrical system station allows pilots to see problems with wiring, especially important as airplanes age and wires chafe, losing their insulation — which can lead to shorts, system failures and fires. Evidence of wire chafing definitely means a call to a mechanic for assistance; however, it also requires that the pilot be able to describe precisely where the chafing is noticed and what appears to be rubbing on the wiring, such as an overly tight tie-wrap, structural frame or bracket or other wires. Cuts in insulation and evidence of burned insulation are shown as examples of no-go items. With a mechanic, the pilots engage in a discussion of battery maintenance and condition including low voltage and the dangers of over-voltage. Included with that topic is work with battery cables and attaching hardware, because worn or frayed battery cables can be a no-go item.The pilots also spend some quality, dirty fingernail time with a more advanced airplane, usually a piston twin. With its faster landing speeds, it is a good vehicle for consideration of tire wear, so examples of safe, marginal and unacceptable tires are shown along with instruction on where to find wear limits published. Different types of shock-absorption systems on landing gear are discussed, and wear limits and appropriate servicing of the different types explained. Hydraulic systems are covered, including servicing of reservoirs and an explanation of the servicing a pilot can do, and a warning that some airplanes cannot have fluid added to the hydraulic system unless the airplane is up on jacks and the gear retracted.In another lab session, the grubby-paws opportunities continue with examples of cracked, gouged and seriously worn propellers being available for examination. The effect of aging on hoses and flexible fluid lines is shown.In general, if something can wear out or break and it can be observed on a preflight, the seminar has an example so that the pilots can see the good, the bad and the ugly. To me, the seminar is an extremely worthwhile way to spend part of a day.

Broaden the Audience

I asked Professor Whittaker how the seminar could be taken on the road or somehow made available for pilots to view secretly so that they do not have to admit they are not a mechanical genius. She said that the goal is to continue working with PAMA and WAI to film the seminar and all of the examples and load it onto a DVD. The idea will be for it to be initially available to local PAMA and WAI chapters as the basis and resource for them to put on their own seminars. It is intended that the DVD will be in-depth enough that it will be a stand-alone presentation; however, the chapters will supplement it with examples of components in various stages of wear for hands-on work, and local mechanics will assist with the seminars so that pilots get the opportunity to interact with aircraft maintenance technicians.Professor Whittaker said that another goal is to make the DVD presentation descriptive enough that it is a valuable instructional tool even in the absence of sample parts for hands-on experience by the viewer.I spoke with Brian Finnegan, the president of PAMA, and he enthusiastically supported the idea of the preflight seminar program and getting it onto a DVD for wider circulation. He is a strong supporter of maintenance education for everyone involved in aviation. He pointed out that maintenance education benefits all pilots because it serves to increase their level of knowledge of their airplanes, which increases the level of safety of operation. He encouraged Professor Whittaker to go forward with the DVD program.The Women In Aviation chapter at Western Michigan University has been extremely helpful in facilitating the workshop. The workshop is one that WAI chapters across the country, and even internationally, can organize for the benefit of their members as well as pilots in their communities.I, for one, am looking forward to being able to buy a copy of the DVD. That way I can look at it in the privacy of my home, with the curtains drawn and the lights off, so that I can learn about all those gizmos on the airplanes I fly and do not have to reveal to anyone that my one mechanical gene was surgically removed when I was nine.See you next month.