The abbreviation CDI stands for Cumulative Damage Index in the military field, especially in the US. You can find more abbreviations starting with CD here. Also take a look at our list with military acronyms.
The Wear in One Number
The Cumulative Damage Index combines the load history of an engine into one value: how many start cycles, how much temperature stress, how much wear. The CDI tells the maintenance planner how much life the engine has already consumed.
Why Damage Must Be Counted
A jet engine does not wear evenly: every start stresses more than an hour of cruising flight, every hot day more than a cool one. The damage index weights these loads – and shows when an inspection or overhaul is due, before a failure occurs.
CDI appears in this meaning mainly in engine maintenance documentation. For twin-engine aircraft, the values are counted separately: CDIL for the left engine, CDIR for the right one.
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