A&P-Designed Tool Simplifies A Tough Job

If you make mechanics do something awkward for long enough, one of them's going to turn into an inventor and solve the whole problem. That's what happened when "Hollywood" Perin finally got tired of the grief involved in adjusting cable tension on the Boeing 737s he works on for a major airline.

Cable rigging is important to safe flight -- there have been fatal mishaps because a cable was not tensioned properly. Rigging needs to be checked, and usually adjusted, at each periodic inspection. So anything that makes rigging easier will find a happy home in many toolboxes.

Try to visualize how the thing is usually done. Control cables are normally tensioned by putting a tensiometer on the cable and then using an adjusting tool. The most common tool resembles two C-clamps joined by a length of bike chain. First, any slack is removed from the cable. Then, one clamp is fastened to each turnbuckle end to hold them in alignment. Then, a wrench is used to turn the turnbuckle But this arrangement, while it allows a mechanic to tension the cable, has some downsides:

• The clamps take two hands to put on and can be hard to use in the tight spaces where these turnbuckles live (for instance, in the nose gear compartment of that 737).
• Usually there's enough other stuff in the way that it's very difficult to swing most wrenches very far. It can be hard on an A&P's knuckles.
• And you're constantly removing and replacing the wrench and that increases the likelihood that you drop it -- and everything stops until you can find it again. You can't leave a tool inside an airplane.

That's not the only potential problem. An alternative tensioning tool has a spring in place of the bike chain. It has all the above problems, plus puts tension of its own on the cable which can interfere with getting a proper reading on the tensiometer.

Enter Kid Rig.

Kid Rig is a two-part tool which can be attached to a turnbuckle entirely one-handed. Once it's snapped into place, no part of it can fall off until you deliberately take it off. To operate it you turn a speed-wrench with your fingers, and again, operation is entirely one-handed.

It has a cleverly designed multi-sized end that handles the turnbuckle ends that A&P's know as "3, 4 5 and 6," sizes. The full nomenclature for the turnbuckle ends is MS21260-S3,-S4,-S5,&-S6 (same as NAS669) -- they come in long and short varieties, both of which this tool handles by having two sets of interchangeable "anvils" or jaws -- and for the bodies MS21251(same as NAS649; again, both long and short varieties are supported.

When you slip Kid Rig into position, it automatically mates with the right size jaws. The more you look at the tool, the more you see the originality of its concept and design details. (Some Kid Rig features are patent pending).

The material is high-silicon 6061 aluminum, which won't mar or scratch the cable turnbuckles. It meets the MilSpec non-mar requirement. "A scratch creates a stress riser, and can lead to cracks," Hollywood warns. All parts are machined from billet stock.

I have to admit, I have never tensioned a 737 control cable in my life, and probably never will. But what caught my eye was the bow-shaped display showing the tool off. It turns out, Hollywood ("That's been my nickname for so long even my family calls me that") fabricated that too. "That shine is polished aluminum. I bent it on 3/4 inch tools and you can see it's one inch square tubing... that was a challenge."

"I love building things. I've built cars, race cars, bikes, and airplanes -- well, I've helped build airplanes." Having seen the workmanship he puts into a tool and a display stand for same, I wouldn't question the airworthiness of anything he worked on.

The gleaming bow hosts three cables with different sized turnbuckles and passersby are invited to try it. (The one perfect addition to this demonstration would be one of the old tools for hands-on comparison). This cable-tensioning neophyte had the hang of it in seconds (after sufficient dual instruction to satisfy the insurers, of course). Trying it hands-on makes the utility of the tool apparent (for those who can't try it personally, there's a brief video on the Kid Rig website, linked below).

Kid Rig is only the first product from Kid Rig LLC, Hollywood promises. The next will be a Kid Rig cable tensioner that works just like the present model, but handles smaller turnbuckles, and a larger one "for that big Number 8 size they have on the Airbus."

"Yeah," said a showgoer, whose informed questions had already marked him as another line A&P. "It is a big one. But there's only that one cable to do on the Airbus."

"But isn't that one a pain in the neck to get at?" Hollywood countered.

"Yeah," the mechanic said. "Yeah, it is," and he took one of Hollywood's cards.

FMI: www.kidrig.com