The Way It Is And The Way It Was

Before you dive in and start tearing something apart, take a moment, close your eyes, and imagine yourself putting it back in working order. Through the course of your little thought experiment, you may realize that you don’t have a clue how it was put together. Which leads us to the following troubleshooting commandment, sent down from on high:

Lo! Thou shalt keep track of things as you take them apart.

Some very simple things will help you follow this decree: grab a pencil and paper and take some notes, make a sketch, or take a photo. They say a picture is worth a 1,000 words: one can save you countless man-hours when it’s time to reassemble. Please, grab your camera and take some snapshots before everything is in pieces. On even the simplest of machines, there’s just too much minutiae to ever contemplate memorizing everything. Even if you have a general sense of where things go, there are a lot of details that could potentially be important: positions of dials, gears, levers, fluid levels, etc. Also, keep in mind that sometimes a fix may take a long time to materialize. You might be able to remember what the machine looked like yesterday, but you might not be able to complete your repair in such a short time frame. If you have to order parts that take weeks to arrive or the repair is far down on your priority list, there’s the possibility it may be a long time before reassembly. Notes and photos will ensure you can easily pick up where you left off.

If you’re working on a digital device, the equivalent to a camera is backup software. Use these tools to take a “snapshot” of a system before you start messing with it: should your efforts go awry, you can later return it exactly to its previous state by restoring the backup. There’s really no equivalent in the mechanical world, so take full advantage of this difference!

On a related note, if you’re contemplating taking something completely apart, you might want to stop and ask yourself: “Why am I doing this?” It’s a gross violation of the “change just one thing” principle to start a troubleshooting exercise by creating a large pile of pieces on the workshop floor. If you’re vigilant about making only one modification at a time, rigorous documentation won’t need to be a priority (like it would be in a complete teardown). Adherence to the “one thing at a time” rule means you’re always just a single step away from how you found things.

Paper and pencil: low-tech, but important, tools for troubleshooting.
(image: Brendan DeBrincatCC BY 2.0)

The “Way It Was” May Be WRONG!

Let’s say you’re troubleshooting a problem, painstakingly keeping track of how the components fit together: their order, relative position, etc. You do this because you know it’s immensely easier to put something back together if you remember what it looked like before you took it apart. You deftly wield your weapons: a camera, pen, and paper. You take photos, write notes, draw sketches, and perhaps even talk into a voice recorder where you describe what you’re doing as you dismantle a complicated piece of machinery. Well done, Troubleshooter.

However, be prepared for the following: you think you’ve discovered and isolated the problem, replaced the failing part, and put everything back exactly the way it was. It appears to work for a while but then, the problem reoccurs! You scratch your head, replace the suspect component(s) again, and it breaks down again. Reading the manual, you discover that the previous person who serviced the machine put it back together wrong. Consequently, all your meticulous work to document the machine’s state had the effect of preserving the errors. Remember: working or not, how you find a machine is not the same as its ideal state. In some cases, it can be a long way off from “ideal.” Who knows how many well-meaning but uninformed people touched it before you? Their repairs or modifications may or may not have been up to snuff. They may have put the machine back together in such a way that it will “work,” but not in all circumstances or in a degraded manner that lessens the life of its component parts.

Automated diagnostics are a great way of catching the Some-Idiot-Put-It-Back-Together-Wrong type of problem (but remember, sometimes that idiot might be you!). Maintenance logs can tell you who touched a machine last. If those aren’t available, I would recommend simply being aware of the environment: do a visual scan of the machine and the general area around a system before starting. Does anything look out of place or different from what you’re used to seeing? Even better, ask the operator/on-site guru about its repair history. If you see something that doesn’t make sense, let the possibility enter your mind that the machine has not been put back together correctly.

Singapore Airlines 747
When working on one of these, improvising is discouraged (and probably illegal).
(image: John Murphy / CC BY-ND 2.0)

Some industries have adopted practices to prevent sub-standard repairs and deviations from the ideal system specification. In aviation, the Type Certificate regime is very strict about what kind of parts and procedures can be used to repair a particular airplane. In fact, certain repairs may be mandatory! Imagine getting a notice saying that you must repair your refrigerator by a certain date and in a certain way or it can no longer legally be used to chill food. That would be overkill for a refrigerator, but in the high-stakes world of aviation some repairs can’t wait and must be done a specific way. Mechanics who work on Type Certified aircraft are required to maintain the ideal “type” and are not allowed to deviate from it. The idea being that clever “hacks” might end up making an airplane unsafe and kill you. Of course, adhering to the Type specifications of an aircraft doesn’t necessarily mean it’s safer in all circumstances, only that it’s been scrutinized and documented. This strictness has a cost: there may be only one legal way to fix to a particular problem. Novel, cost-saving repairs might take a long time to be approved because of the rigorous review process. Even if you work under a heavily regulated maintenance regime like the aviation industry, you still need to be on the lookout for “the way it is, is wrong.” Regulations in place or not, reality always has the last word on whether or not a previous repair was completed correctly.

BS 1363, 13-amp plug
Parts that only fit one way help prevent repair errors. Alas, not everything will be as well-designed as this plug. Components installed in the wrong place, or in the wrong way, are just another way a previous repair may have been botched.
(image: jkfid / CC BY 2.0)

Lastly, parts and connectors that will only fit one way or safeguards that will only allow manufacturer approved parts are yet more ways to prevent a machine from deviating from its ideal state over a lifetime of repair and regular maintenance (these are sometimes a revenue generating ploy too, see: printer ink).


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