People loosely refer to any driver for six-sided socket-cap screws as an Allen wrench or hex key, but many manufacturers produce such tools. One year, I found myself spending every Thursday in the outdoor back lot of the New England Air Museum, freeing three 28-cylinder R-4360 engines from their crushed nacelles and bent propellers. A tornado had hit the museum in 1979, destroying many classic aircraft. Only their engines were saved. A friend and I had bought three of them.

One was from a C-124 Globemaster and, although I had a 3/4-inch hex key that fit its seven engine mount bolts, the available space did not allow room to swing a conventional extension bar. Remembering the all-angle capability of Bondhus' balldrivers (a hex ball on one end of the key), I ordered a 3/4-inch example and awaited its arrival.

Bondhus 20199 Balldriver L-Wrench Double Pack
Bondhus claims its balldriver L-wrenches manufactured with proprietary Protanium steel are as much as 20 percent stronger than those produced by its competitors. ProGuard finish is intended to prevent corrosion. Bondhus is based in Monticello, Minnesota.Amazon

The next Thursday I was on site with my new tool—weight: 1 pound, 13 ounces—and an embarrassingly long extension bar. The engines had been outdoors, resting on sand, for 20 years. Okay, let’s do it. I put the ball end into the most accessible of the seven bolts, attached the extension bar, and pulled. It took a lot of torque but the bolt turned. Success!

One by one, I removed the bolts. I was feeling good. This was working! Soon I could construct a wooden sled on which to place the bare engine, and it could then be forklifted onto a car trailer; each engine weighed 3,500 pounds.

Sorry, one bolt—the last one—said “no.” I looked at the slender neck that joined the hex key to its ball end. Not very big, but I’d been applying a lot of torque and six bolts had said “yes.” I had nothing to lose by applying all the torque I could muster. If the tool broke I’d be embarrassed to have destroyed it but in a good cause.

I pulled and I pulled some more, thinking about the long bar I was using, and the terrible stress that I was putting through the slender 0.570-inch neck of the balldriver. Then I felt the tool yield. Or I thought I did. Or was it the fastener? The bolt did turn, and the engine was free of its mount. When I examined the tool, placed against a flat surface, I could see that it had not twisted. Strong stuff.

I finally gave away those 4360 engines to good homes, but I’ve kept the tool.