Continuing Ed

A benefit of cleaning up our act

You can't deny the catchy appeal of the clich� promising the exhilaration of the enlightenment that surely comes if only we would "Think outside the box!" Well, forget it. As pilots, our attention is rightfully focused inside, if not the box then the airplane. (Of course, we're not so focused inside that we don't spend most of our time looking outside of the aircraft for traffic.)

That clich� refers to a metaphorical box, the confines created by habit, repetition, and familiarity. An airplane, on the other hand, is a physical "box," a machine with an exterior skin, internal structure, one or more engines, and a cockpit. The cockpit, with its yoke, pedals, panel, switches, instruments, gauges, and avionics, is the pilot's box. It's where we spend our time and expend our energies.

That's not to say we never come out of the box, that we completely ignore the rest of the airplane. Why, we do preflight inspections--the walkaround, where we look at this, wiggle that, check, feel, and confirm. It's our opportunity to look at and evaluate the condition of the entire structure, although admittedly it's a cursory examination of a relatively complex piece of work.

If ever you want to take a crack a much closer, more detailed look at the airframe, you might try washing and waxing the airplane and cleaning the interior.

My son and I are in the midst of doing just that. We went to the airport the other day to detail the airplane--degrease the bottom and landing gear, wash and wax the exterior, clean the cabin, and shampoo the carpets. It's a big job, somebody's got to do it, and that somebody was my 16-year-old son. He's in need of discretionary funds (something about the cost of maintaining a girlfriend), and he gets paid handsomely for rubbing on the airplane. I get to help him--gratis, of course.

It's worth the considerable effort. When all is finished the airplane looks just great. We're proud of our airplane, and when it sparkles inside and out we're even more pleased with it. People notice, and that makes it even more pleasurable to own and fly. The thorough cleaning and waxing may even save some money in the long run by extending the life of the exterior paint and interior leather and carpets.

My son probably wouldn't understand, but the benefit for me of sharing in the backbreaking work is the opportunity it affords to examine the airplane inch by inch, rivet by rivet, strut by strut. The painstaking cleaning and polishing process always reveals something--an inlet, outlet, vent, or tube I hadn't noticed before or had forgotten about. What is on the other end of that vent or inlet? What is the slight stain trailing aft from the mouth of that tube? Is it a cause for concern? Such a discovery sometimes calls for a trip to the pilot's operating handbook or maintenance manual to research the answer.

The worst part of the job--degreasing the landing gear and belly--also can be the most revealing, especially if it's a retractable landing gear. What better way than scrubbing on brake calipers, hydraulic lines, struts, and trunions to try and identify all the parts and pieces of the component and figure out what role each plays in the big picture?

Have you ever spent time on your hands and knees underneath a low-wing airplane just staring at the brake assemblies, wheel axles, gear wells (if retractable gear), and gear doors? It's the best way I know of putting confusing POH schematics into context to understand how the system actually works, and what the parts look like.

It's also a good way to identify the more vulnerable parts, items that should be closely checked on every preflight inspection. For example, most nosewheels have a tow limit--the maximum angle that the nosewheel can be turned while being towed before something will snap. If that occurs, you've probably lost all steering control except with differential braking. This would be very nice to know before you taxi away from the parking spot.

The detailing process also is a great opportunity to look for trends and problems that aren't readily discernable on a typical preflight inspection. About a year ago we were cleaning the airplane at the end of a cloudless day when the sun was low on the horizon. The tail was pointed directly into the setting sun, which meant that golden sunlight flooded the entire skin on the top side of the airplane. The only shadows cast downstream came from the slightest bump or rise on the skin--in other words, every rivet and seam.

As I wiped down the vertical fin, I noticed a strange shadow pattern falling across the surface of the fin. I couldn't identify the source until I inspected even more closely. It turned out to be slight bubbling in the paint caused by unseen corrosion.

The airplane lives in southwest Florida, and around here minor surface corrosion on the aluminum skins of airplanes is fairly common. It's not a serious problem as long as it is detected before it begins to eat into the cladding on the aluminum, and is treated. Although we had failed to detect the corrosion previously, the late-afternoon discovery during the cleaning exercise enabled us to nip the problem in time. No harm, no foul other than the cost of the fix.

Previously undetected subsurface corrosion was an unusual find, even during the kind of detailed inspection that occurs when washing and waxing the aircraft. More typical is tracking down the source of fluid leaks, especially on the underside of the aircraft, and identifying the cause of the leak. And there can be lots of them--dirty, black streaks of dirt, dust, metal, oil, grease, hydraulic fluid, gasoline, battery acid, even soda spilled inside the cabin that has leaked through a drain hole or skin lap.

When I crawled underneath the airplane the other day to degrease the belly (my son drew topside duties this time), I discovered a new gash of gook trailing back from a skin lap just behind the nosewheel door. The thick, reddish goo looked like hydraulic fluid. If so, it had to be coming from the brake master cylinder or hydraulic power pack that operates the landing gear and flaps.

I thumbed through the maintenance manual, which we keep in a file drawer in the hangar, but it did not answer my questions so I called Edd Switlik, who runs the local maintenance shop. He guided me through some troubleshooting procedures, and on the basis of the findings and my description concluded that it's old hydraulic fluid that has oozed out. Watch it closely for further signs of leaking, he said. In the meantime, the airplane should be good to go.

Thus satisfied, I crawled back under the belly and, with degreaser wand in hand, resumed my search for enlightenment outside the box.

Mark Twombly is a writer and editor who has been flying since 1968. He is a commercial pilot with instrument and multiengine ratings and co-owner of a Piper Aztec.