Originally Posted by
JohnDixson
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The pilot can do his due diligence with regard to the engines meeting spec power, but then be undone by incorrectly marked loads, or more often unmarked loads which come with a guess* as to what they weigh and various combinations of the same. Now, what sort of power check can one do in that case?
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Given the appropriate performance charts, they can be ran in a "reverse" direction to determine the gross weight. However, very few manufacturers (and the FAA doesn't require them) provide the appropriate charts. Military helicopters and derivatives usually have the necessary charts. With enough information, an individual could construct what is needed (I have done this for several helicopters).