Intent behind Bell 205/212 WAT charts?
Might seem like a pretty simple question, and i've always thought i had a pretty good understanding of it until someone asked why the 205/212/412 has it but some other bell products do not.
Understandably it provides for a take off/landing weight limitation based on factors of temp and altitude. The WAT chart is advertised in the limitations section, so clearly it becomes a limitation as opposed to a performance reference like that of the HIGE/HOGE charts. However, the HIGE charts mirror/inorportate the WAT chart so perhaps its intent is more of an engine performance indication.
The 212 WAT chart envelope was expanded with the upgraded 412 T/R which would perhaps imply the reasoning behind the WAT chart in the first place was that of tail rotor authority.
Perhaps it was for certification and to ensure compliance with H/V chart. I may be overthinking it, but any thoughts on the charts true intent would be much appreciated. Thanks!