I always thought the principle of shrink-wrap was simple. You had a floppy piece of what looked like an inedible form of black lasagna and you put your wires in it. Then you applied heat and the floppy black stuff shrank until it met the resistance of the wires and bound them in a granite grip.

That was before I met George Kennedy of A.E. Petsche Company at an NBAA show. Humping my weary body towards an exit, I noticed George’s stand featuring shrink-wrapped products. I didn’t mean to be a wiseguy, I was just tired and when George offered to answer any questions, I allowed as how his products seemed kind of boring.

Talk about lighting a fuse under a rocket. George was just as tired, but he ricocheted like a pheasant out of cover, grabbed his heat gun, and started a demo of his products that left me limp.

First he showed a kind of tubing that was designed to clean up a bunch of wires going in the same direction. With a simple tool, he laid the wires in the tube, which closed on them with no chance of one getting free.

I was about to turn away when he introduced a few variations on the subject of shrink-wrapping, like wires going off at a 45-degree angle and others splitting in Ts. When I expressed wonder, he explained the process.

Contrary to my expectations, it isn’t just a matter of taking a special material and shrinking it down. In fact, what you get when you order shrink-wraps are products that are part way through a sophisticated process.

To produce these shrink wraps, the manufacturer first extrudes or molds the finished design, using special materials. These, in the Raychem versions promoted by A.E.Petsche, are then exposed to electron-beam irradiation. Finally, heat and compressed air are used to expand the finished item to easily accept the required wires. This is the product that you, the user, get when you order shrink-wrap.

When you then use a heat gun to do the shrinking, the material quickly returns to its original molded or extruded form. In the process, of course, it grips your inserted wires tightly. The final result is a neat and clean job of packaging.

The chemical changes that take place are well understood by Petsche’s engineers. Suffice it to say that you can get what you want in many different models for a neat, clean installation in any aircraft. It’s a far cry from the original floppy tubes that would just shrink down until they encountered the resistance of the contained wires or cables and then quit. The result was a tightly closed package but not one that would lend itself to sophisticated configurations and easily traced breakouts.

Today, according to A.E. Petsche, customers can work with their engineers to have many shrink wraps designed to their own specific requirements.

3M Fiber Optic Flashlight

The new Fiber Optic Flashlight system from 3M Aerospace consists of a flashlight and a 7- or 12-inch flexible fiber and cone assembly that directs bright light onto the illuminated area. I’ve been using the 7-inch Fiber Optic Flashlight to inspect my airplane, and it is a terrific light, much brighter than the flashlights that I had been using. The brightest light comes from the tip of the fiber optic rod, which is about 3/8 of an inch wide, but light also comes from the sides of the rod, which helps light up an area being inspected. The rod is flexible, too, which makes it possible to position the light in various directions when there are no hands available to hold the light. The Fiber Optic Flashlight comes as a system with the fiber optic rod and flashlight and selling for $60 to $80, or you can buy just the fiber optic portion for about $35, if you have the right flashlight already. The Fiber Optic Flashlight system is perfect for technicians who work inside fuel tanks as it is UL listed for Class I, Division I, Groups C and D allowing use in areas where flammable concentrations of gases, vapors, or liquids exist. www.3m.com/aerospace