Maintenance documentation is often authored in a controlled language, not ordinary English. Translating it as if it were prose defeats the point. What Simplified Technical English is, and how to handle it in and out of the source.
- The source is a controlled language, on purpose
- What this changes when translating out of it
- And a note on authoring for translation
The source is a controlled language, on purpose
Open an aircraft maintenance manual and the English looks oddly stiff — short sentences, one instruction per line, the same word for the same thing every time, no synonyms for variety. That is not bad writing. It is a controlled language, most often ASD-STE100 Simplified Technical English (STE), designed so that a procedure cannot be misread by a technician working under time pressure, possibly in their second or third language.
STE restricts vocabulary to an approved set, limits sentence length, bans the passive voice in instructions, and forbids using one word for two meanings. The whole point is to remove the ambiguity that ordinary English tolerates. A translator who does not know they are looking at STE will "improve" it — vary the vocabulary, combine the short sentences — and quietly reintroduce exactly the ambiguity the source was engineered to eliminate.
What this changes when translating out of it
Consistency is the requirement, not a stylistic preference. If the source says "remove" every time, the target must use one approved verb every time — not three near-synonyms a good literary translator would reach for. The termbase is not a convenience here; it is a safety control.
Structure carries meaning. The one-step-per-line layout, the warning-before-action ordering, the numbered sequence — these are part of how the instruction is understood. Preserve them. Reflowing a procedure into flowing paragraphs is a defect even if every word is correct.
Some target languages have their own controlled-language expectations. Where the destination market or operator specifies a controlled or standardized style for maintenance content, translating to ordinary target-language prose will not meet it. Confirm the target-side requirement at kickoff, not at review.
And a note on authoring for translation
If you author in STE, you have already done most of the work that makes translation cheap and safe: the vocabulary is bounded, the sentences are short, the terms are consistent. That content translates faster, matches more against memory, and generates far fewer translator queries than free-form English would.
The failure case is mixing registers — an STE procedure with a marketing-style introduction, or free-text notes dropped into a controlled manual. Those transitions are where translators guess and reviewers argue. Keep the controlled content controlled, and mark clearly where it stops.