Writing a procedure a technician will actually follow

A procedure is not a description. It is an instruction issued to someone who is standing in front of a machine, often in poor light, frequently in a second language, and always under time pressure. Almost every failure of maintenance documentation traces back to forgetting that.

The rules that carry most of the weight

• One action per step. If a step contains “and”, it is usually two steps.
• Active voice, imperative mood. “Remove the extinguisher”, not “the extinguisher should be removed”.
• One word, one meaning. If “check” sometimes means inspect and sometimes means verify, it means neither.
• Short sentences. Twenty words is a long instruction. Most should be under twelve.
• Say the condition first. “If the gauge is not in the green zone, replace the extinguisher” puts the test before the action.

If the reader has to decide what you meant, the procedure has already failed.

These are the bones of ASD-STE100, a controlled-language standard written for aerospace maintenance and applicable almost unchanged to heavy industry. Its value is not elegance. Its value is that it removes the space in which two competent people can read the same sentence and do different things.

It matters more, not less, when the workforce is multilingual, and it makes translation dramatically cheaper, because unambiguous source text is the only text that survives translation intact.