Every part on a certified airplane must at some point be approved, but that doesn’t mean that the plane you fly isn’t full of bogus hardware. Bogus hardware that doesn’t meet the minimum FAA standards for safety has been discovered everywhere — from the major airlines all the way down to the best local FBO. The airlines have recently been dealing with a parts scam from an Italian distributor, which sold old parts as overhauled when in fact they were not and in some cases had reached the end of their service lifetime. Ten years ago, substandard parts were found in the general aviation fleet as well.
AMID A FLURRY OF REGULATIONS AND NOTICES…
The sources of the bogus hardware are usually driven out of business, and with them, the problem sort of goes away… unless you happen to be the owner of a plane that was maintained in the original time frame. In that case, your plane may be full of bogus hardware, and unless your shop or you know how to spot it, you might never even know it’s there… until it is too late.
Example: Ten years ago, our friend bought a stainless steel hardware kit from a reputable parts house. The price of the kit was quite attractive, and the chance to eliminate all the rusty fasteners on the plane was a similarly appealing deal for the owner. He purchased the kit, and then installed it with his FBO over the course of an annual inspection.
The kit included all the hardware for his airplane. It included replacement screws for his inspection covers, including the wing bolt wraps. It included screws for the interior. The kit even included screws for the fairings.
The only problem was that the kit didn’t contain a single LEGAL fastener!
A PROBLEM YOU MIGHT HAVE
Our friend unknowingly flew around with this hardware for ten years before a sharp shop caught the problem. What tipped them off was the way the screws sat in the countersunk holes — they stuck out just a little bit. No matter how hard the shop tried, they couldn’t get the screws to sit correctly. So they pulled one out, and compared it with a legal screw.
Problem 1: The chamfer angle on the head of legal aviation screws is 100 degrees. Normal hardware that you can get from a hardware store (read: not legal for certified airplanes) has an angle of 82-degrees. The 18-degree difference is enough to make the screws not seat properly.
Problem 2: Aviation screws are snubbed — the sharp end is clipped off, and the end of the screw is usually flat. Non-aviation screws have pointed ends, to facilitate use in their more standard applications… as wood screws!
There are some basic indicators that your airplane might be affected (read: infected). When you wash the plane, does your wash rag catch on the countersunk fasteners? When you look at the access covers, do the screws stick out a little, no matter how hard you try to get them to sit flush? If they do, you may have a problem with BOGUS HARDWARE!
If you suspect bogus hardware is in your plane, talk to your mechanic about your concerns and have him/her check it out. In the case of our friend’s plane, the initial sighting by the mechanic led to further inspections, which resulted in the replacement of all the hardware used to secure the inspection covers in the plane. While this did cost the owner some money, having the right hardware in the plane is important. It is important because aviation hardware is designed to take specific stresses and strains. Non-aviation hardware may or may not be up to the challenge, and an improper fit can cause more problems than an access cover popping off in flight. An improper fit can encourage stress cracks to form.
BOTTOM LINE: Know that the fasteners in the airplane you fly are the same kind the designers originally intended to put there! Check the hardware on the airplane you fly — today. If you use the suggestions we have listed above, you stand a very good chance of finding this hardware before the FAA does. Plus, the inspection process itself will serve you well; the more detail you know about the airplane, the safer you will be. By the way, a good FAA inspector can spot bad hardware from across the ramp, and if they find it on your airplane, you will be grounded until it is replaced. In this case, as in most, being legal means being safe.