| |
Plane Talk MAXIMIZING YOUR INVESTMENT
What You Don’t Know Can Hurt!
 Some people avoid going to the doctor because they don’t like to think about being sick. It’s as though ignoring a problem will make it go away, when most of the time, ignoring a problem makes it worse.
The same can be said about corrosion in older general aviation airplanes. Although many parts of the airplane are inspected annually, few aircraft owners take the extra step of going beyond the annual inspection and looking for corrosion at one of its most likely points of origin: inside the cabin.
That’s because getting to these areas can be difficult, and because treating corrosion can be expensive. And rather than tackle what could be a costly and time-consuming project, many owners and repair shops prefer not to think about it, leave well enough alone, and hope that the damage won't become severe until someone else owns the airplane.
But Dennis Wolter owner of Batavia, Ohio-based interior renovator AirMod, isn't the kind of guy to ignore corrosion problems. “I won’t bring an airplane in here and ignore something like that,” he said.
Wolter said that when refurbishing aircraft interiors, he is seeing more and more aircraft suffering from severe and sometimes debilitating corrosion inside the cabin. It’s an insidious problem that is hard to spot, and then difficult and expensive to treat. And yet like any illness or affliction, it has to be dealt with.
“Most mechanics don't want to mess with it because it’s very time consuming,” Wolter said. “You would have to remove head-liner panels and upholstery … then you remove all the insulation, mask all the wiring, cables and hoses, get some Scotch Bright and you start scrubbing. An easy one is 25 hours, a tough one is done in 60.”
Corrosion is damaging to aircraft because over time it can weaken the metal structure leading to cracks that could render the aircraft grounded and require expensive repairs. It reduces the value of the investment you have in your airplane. So if you want to protect that investment, it makes sense to inspect the aircraft regularly and aggressively seek out corrosion.
In some cases, environmental conditions such as where the aircraft is kept or flown have led to the corrosion. This is why some aircraft buyers prefer “dry country” airplanes, those that are based away from the corrosive salt-sprinkled air of the east and west coasts. In other cases, glues and other chemicals applied to metal surfaces of the airplane cabin, either by the manufacturer or by others modifying the aircraft, can begin a nasty, corrosive process.
Another very common source of corrosion is moisture that gets trapped inside the aircraft on hot, high-humidity days. Wolter said damp air inside the airplane condenses at altitude and gets trapped inside the ceiling and against the walls of the airplane, usually hidden behind the insulation and against the metal structure.
Over time, this trapped moisture can begin a corrosive process in the structural metal of the aircraft. It’s not good on any aircraft, but certainly worse in a high-wing Cessna, which has the bulk of its wing spar structure in the ceiling of the airplane.
Other sources of corrosion include leaks from antennas or poor window fittings that are not repaired, allowing moisture to settle beneath the carpet and the floor of the aircraft, eventually leading to corrosion and weakness of the floor. Low-wing aircraft, if they do not have drain holes in the floor, can also suffer corrosion because the water gets trapped and can threaten the structure and weaken the airplane.
In short, every aircraft can have a problem inside the airplane that can lead to structural issues in some manner down the road.
While your annual inspection may include an inspection of the wing and tail structures, Wolter suggests getting inside the airplane cabin and pulling the insulation away from the metal.
“On a pre-purchase inspection, you can pull the access panels down and pull enough insulation out of there to tell,” Wolter said. “Someone who knows what they’re looking for, it’s not going to take much at all … to see if there’s anything cooking.”
Any corrosion you find should be cleaned and the interior surfaces of the cabin should be corrosion-proofed before insulation and the interior is re-installed.
Wolter suggests checking dry country airplanes every three or four years, while airplanes that are based or regularly fly in areas where there is sea air should be checked annually. He also notes that even aircraft that have been factory corrosion-proofed can have corrosion problems. Some aircraft have had materials glued to a treated piece of metal, and the glue can become a problematic source of corrosion.
If you have corrosion and take the time to fix it, there is an up side later when you go to sell the airplane.
Wolter said clients have told him that having before and after pictures of their aircraft, that show how the problem was dealt with and how future problems were prevented, actually increases the resale value of the airplane.
—Sean Fulton
|
|
|
|
