One of the interesting things at Airbus was the way they merge the hull sections, wings, tailfins and stringers, the internal bracing struts. For this purpose Airbus’ engineers have specified a range of adhesives, bolts and rivets, depending on the stresses acting on the airframe during flight.
I was specially interested by the high-strength HI-LOK rivets. These have a flat head on one side, obviously, to ensure the aerodynamic properties on the outside of the hull, then they are held in place with a recess in the bolt, the threaded bolt head is screwed on, cutting into the thread – until the head shears off at a defined shear-off load. This ensures correct tension on the one hand and on the other mitigates the risk of rivets coming loose.
All this reminded me of DMM’s Fred Hall commenting on Chinooks: fifty thousand rivets flying in loose formation. Indeed. It is a good idea to keep those rivets tight…
It also made me think of the story about the wrenches at Rolls Royce.
Apparently in the fifties Sir Henry Royce, himself a skilled mechanic, was concerned about bolts being correctly tightened. In order to encourage this he set about designing a set of special wrenches. Sir Henry was of the opinion that a skilled mechanic could correctly tighten all the nuts using the correct length spanners or tommy bars that he stipulated. It was significant that when put to the test, nuts tightened in this way were in fact found to be tightened to the torque tightness which was decreed correct in 1955.
These are both examples of how making tools intuitive can contribute towards ensuring correct handling and behavior. If a tool is clunky and counter-intuitive, the likelihood of it being used incorrectly or causing issues is higher than if considerations of how a tool shall be used correctly are a deeply ingrained part of the product’s design.
I am not suggesting this is always necessarily an easy thing to achieve, but I believe it is something we ought to strive for and therefore focus more attention on. These considerations can be reflected by the physical properties of a tool, the way an system is configured or what information is provided for the end user to base his or her decisions on.
A classic arborist example for such an assembly to my mind is the ring saver: an elegant, intuitive solution for a complex problem. The two different size rings with a webbing or rope link between them are practically impossible to misconfigure (if you do, at the worst you have to go up and fetch it, and it will probably have taught you not to thread the rope through the rings the wrong way round), rope friendly and reliable to deinstall in a cluttered environment that a pulley-based saver might struggle in.
Chose your tools wisely, put them to a good use and, where possible, ensure they have intuitive properties that encourage correct handling.