Writing clear, concise, consistent instructions, procedures and manuals is essential for ensuring airworthiness when maintaining or inspecting aircraft.
Say exactly what is meant and say it clearly, concisely, and accurately… ”Garbage in = Garbage out”
A good starting point are the instructions the FAA uses to draft Airworthiness Directives. Following the guidance contained in FAA-IR-M-8040.1A “Airworthiness Directives Manual” will help to create consistent instructions and terminology in Aviation Technical Instructions.
Consistent Technical Terms
Start out by making sure that the terms used are consistent with the definitions of the terms used in your AMM., CMM, IPC, service documents (SB, SL, ICA), GMM, AD and Title 14 of the Code of Federal Regulations (14 CFR). Give instructions in logical order. Use short sentences. Use technical terms when they are necessary, but do not complicate simple instructions by overusing them. Do not repeat instructions for emphasis. Have someone else unfamiliar with the subject matter read the draft to see whether the message is getting across clearly.
Active Voice
Write instructions using the active voice. Technical instructions should speak" to the person doing the work, telling them what to do. In general, the strongest writing uses verbs, and the strongest verbs use the active voice. Avoid using passive voice
Do not use the passive:
- "The attach bolts shall be inspected every…."
- "The seals are to be replaced with…."
Use the active:
- "Inspect the attach bolts every…."
- "Replace the seals with…."
Consistency
Use the same word each time to refer to the same item or action. Do not use synonymous terms for the sake of variety; such use only leads to unnecessary confusion. Conversely, never use the same term to refer to two different things.
Specificity
Use specific terms — do not use "aircraft" (unless it is in the name of something) when a more specific term, such as "airplane," "gyroplane," or "helicopter," is more accurate.
Positive Slant
When the same idea can be expressed positively or negatively, express it positively.
Do not use the negative:
“Does not apply to airplanes with modification {3456}….”
Use the positive:
“Applies to all airplanes that have not been modified ….”
Precision
Use adjectives that are precise. Terms such as "excessive," "adequate," and "sufficient" are unenforceable because they call for value judgments. Instead, define how excessive wear can be measured or what is included in an adequate inspection. Do not use terms such as "prevent", "correct," "preclude," "ensure," "will," or "could" unless they are properly qualified. As an example, do not say that a modification "will prevent engine stall" when what is meant is that the modification "will prevent engine stall caused by ice ingestion." The modification may not prevent engine stall caused by other problems, and imprecise wording may imply that it does.
Notes
Use notes in technical documentation to include information that is explanatory or informational but is not mandatory. Such information should be placed in a note immediately following the instruction it seeks to enhance. Never place mandatory instructions or acceptable alternatives in notes; The FAA considers “note language” to be not enforceable in Airworthiness Directives.
Examples of acceptable notes:
- NOTE 1: The date code stamp is steel-stamped into the lower side of the flap actuator housing. Disregard ink-stamped numbers.
- NOTE 2: During the inspection required by paragraph (a), pay particular attention to the area surrounding BS 920.
Example of an unacceptable note:
- NOTE: The provisions of AD 88-75-23 must be completed before accomplishing any work under this paragraph.
If the instructions contain more than one note, number them sequentially in the order they appear, such as NOTE 1, NOTE 2, etc.
