Rust Never Sleeps


Over they years whenever I’ve had a chance to talk to folks who worked at Beech and Cessna and the other aircraft companies, I always asked them what time frame they designed these single-engine planes and light twins for. Of course they always tend to not want to be specific, probably since they didn’t really know, but I’m sure it was not for even half the number of years and hours the typical GA fleet plane has on it now.

They probably designed then more for hours than years, when gas was cheap and people did lots of flying. The point I’m trying to make right now is the average fleet airplane is well over 30 something years old—well over the design.

Often it’s so deceptive as you can make a 35-year-old plane look great on both the inside and outside (ask for the photos of what the plane looked like during restoration. Any proud craftsman will have such a record to proof the quality and detail to what they went to make this a “like new” airplane.

The big issue is that even the well taken care of 35-year-old plane may look fabulous on the outside with fresh paint and interior, but there will be corrosion in varying degrees, some of it in extremely dangerous places. (At least with planes that have not spent their entire time in a climate-controlled hangar and hardly ever flown.)

Many planes have had both good, attentive owners and far less caring types (hey it’s just a machine. No—it’s a bauxite-based life form). Most owners feel strongly about their airplane.

And just as important was how well the plane was protected from the environment for all those years, as was how often the plane flew and in what kinds of weather, and how it was cleaned on both the inside and outside, and how frequently.

Some poor planes worked their lives for training schools and had a truly tough time in many respects, though their problems may more be from hard use and abuse, while others may have been hangar queens. The point is at these ages, corrosion condition is all over the map on the same age planes.

We Need a Voluntary Corrosion Inspection Program

Most of it you can do on your own when you do your annual preparation or other routine work on the plane. I don’t know how different I am from other owners, but I loved being in and around the plane always inspecting. I continue to both see and read about near disasters, and with these older planes still the vast majority, we are often looking at corrosion as the cause or instigator of the failure, such as we point out often in the monthly Hotline column.

Work with your IA. Tell him why you are interested and any decent inspector (all have different planes they may be particularly knowledgeable about) will tell you where to look in your particular airplane (or he can give you the name of an IA who can tell you) for common trouble spots.

Then you don’t have to wait a year between checks for problems, as that is too long on old planes in our view. What I’d like to see is proactive owner extra efforts to keep an eye out for corrosion. We have to be careful here to stay legal and not start disassembling the plane unless under supervision, say for an owner annual. Though it would be fine to do some dissembling, checking, lubrication and reassembling with a trusted (and lower pay rate) A&P. Check with your inspector first. Some want the plane untouched.

Actually some owners and mechanics make a case for too much inspection and disassembly that can end up doing more harm than good, although I never bought into this argument if the inspection is done properly. I agree there are some really brutal, impatient mechanics out there that I have personally observed.

I think that’s how such thoughts get promoted. It’s the “don’t fix what ain’t broke argument.” Old planes are well past that argument because of the consequences of what happens if they do break.

The last thing I want to see is more FAA legislation, but I’m afraid if we don’t start doing this on our own, voluntarily, there will start to be accidents attributable to corrosion. And if some celebrity or politician gets killed, suddenly there could be way too much of a spotlight on old planes, and additional inspection requirements for all planes over, say, 25 years old or some other arbitrary number—like a special annual checklist for planes over 25 emphasizing corrosion inspection may take place.

There are already ACs out on old planes, and fortunately they are generally proactive and helpful. We don’t want to turn the FAA against us by having them have to respond to political pressure. The Airborne Vacuum Pump business (who virtually owned the market) went out almost overnight a number of years ago when a Senator who was a passenger was killed some years back and vacuum failure was questionably implicated as part of the cause in a twin aircraft. The son was flying, so pilot error was out of the question. Something else had to be blamed in this case rather than pilot error (in our view).

There is a bit of a paradigm shift here in that half-decent video scopes are now available at low prices that allow for not having to disassemble planes beyond normal requirements. You just have to make the effort to use them, and not cause damage with careless use, which is possible.

Work with your IA and find one who knows your type of plane, not just the guy who has the reputation who will sign off anything as long as your check doesn’t bounce, because in the long run you will loose—if not you then your friend or family who trust that you take care of the plane properly. It’s not only your life here, otherwise we would be saying what you do is your business and no one else should care. But we all are involved.

In one recent Hotline write-up, during an inspection in the Jan 2013 issue of Light Plane Maintenance “Corrosion was found on the forward and aft wing spars under the fuel tank spacer blocks (P/N 0523524) in the fuel tank mounting bay. This problem was discovered when the fuel tanks were removed for repair. No visual corrosion indications were noted around the spacers when mounted.” You really need to be on the lookout.

If we don’t start making some special efforts at closely inspecting for corrosion and other vestiges of old age, these old planes are going to start falling out of the sky. Don’t count on a typical annual where the owner wants the cheapest thing possible as a safety guarantee. These are people who actually risk other’s lives, and often try to sneak defects past the IA.

Many IA’s just don’t check that closely or dig that deep since it’s not required (at least not yet). If you read the FARs of the annual it gives an extreme degree of latitude to the inspector how deep to dig for trouble, with very generalized wording.

Another important way to check is look at the logs to see if important checklist items have been done. All maintenance manuals have these hourly checklists. If not much is recorded in the logs, it’s a bad sign.

Many Wings Are Bolted On

That’s not designed so much to scare you, but most wings such as on a Bonanza have 4 very special bolts on each side that have small adjustments that hold the wings on. The true one-piece wing is a rarity and the Mooney is one of the few such airplanes.

But it doesn’t even have to be the wing bolts that fail from corrosion to take a plane out of the sky, but those are not always as easy to inspect compared to an aileron bolt, which can also take a plane out of the sky if it fails. (Warning—You do not pull a wing bolt out to see what condition it is in. A special tool is used to put them in and remove them properly, as well as a rigging jig and special high torque.)

The same concern holds for all the paint jobs and whether the ruddervators or conventional tails or any required control surfaces have been properly balanced after repainting to assure there is no flutter. There are all sorts of things that over the years can add up to make the plane much more dangerous than it should be. You want to be checking logs carefully to assure these things have been done.

I saw a Bonanza whose tail was nearly twisted off. How it stayed on was some one of those odd lucky events that just never normally happens where the pilot walks away from such an in-flight failure.

He was racing the plane in a CAF race at the time and somehow the ruddervators had not been balanced in many years and several paint jobs, and it didn’t show up until the plane was pushed hard in heavy turbulence. He even had the air intakes for the cylinders covered by aluminum plates. Do you know when your required control surfaces were last balanced if your plane has been painted?

Rust Never Sleeps

I’m not picking on specific items here, just giving some general ideas of very critical items that often just never really get checked, nor were they designed to last indefinitely as we are currently attempting to do in a rather grand old age experiment often left to its own devices on how long a part will last until failure.

This article originally appeared in the March 2013 of Light Plane Maintenance.

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