The underside of an airplane is out of sight and thus usually out of mind until the owner peeks downstairs to check something. And there, in all its filthy resplendence, is a flying Super Fund site. How to clean it up? To find out, we recently tested a crate full of commercial cleaners designed if not specifically for this task, then for general degreasing and clean-up. Lasering right to the findings, all of them work, some are better than others, but the overarching consideration is to have a strategy to get this messy job done just frequently enough to keep the airplane clean without getting obsessive about it.
Why Do it?
The reasons for doing this go beyond the cosmetic. Greasy dirt can conceal things youd like to see, like loose fasteners, degrading paint or cracks. The larger issue is belly-mounted transponder and DME antennas, which don’t work well-and sometimes not at all-with a slathering of dirty oil. So, what are we looking for in a degreaser? Something that allows doing the job quickly, easily and without having to slide under the airplane with a creeper much, if at all. Preferably, the product should be just aggressive enough to get the filth off, but not so harsh as to soften the paint. (Some of these degreasers will do that.)
Where possible, we would prefer to avoid having to wear protective equipment for breathing, eyes and skin and, again, some of these cleaners require that. Generally, belly degreasing is going to happen outside, so ventilation isn’t an issue. In a hangar, however, it could be.
Cost is not much of a driver here, but ease of application is. If whatever method you use to degrease is more of a hassle than it needs to be, you wont do it as often as you should.
With these criteria in mind, we bought 16 commercial products from Aircraft Spruce, which constitutes most but not all of whats on the market. Conceding there are other products that might be as good or better, feel free to contact us with your own suggestions.
Cleaner Classes
There are two ways to sort these cleaners-by chemical makeup or by packaging. In the chart on page 10, we sorted the cleaners into three categories-aerosols, spray bottles and mixed solutions, since these relate directly to one of our primary criteria: ease of use.
First, the aerosols. We bought seven varieties of these ranging in price from $5.80 to $24.95. At the expensive end, are LPSs Super Degreaser and CRC Super Degreaser. In addition to being expensive, these aggressive chemical solvents showed signs of going after the paint and, to be fair, they are really not suited for this job. The same is true of LPSs HDX, a trichloroethylene-based solvent. Best to use these sparingly and with both eye and breathing protection. We would spray a bit on a rag and degrease that way, rather than spraying the