Originally Posted by
Windmill Wiz
Be wary of these numbers. In a similar way to the Volkswagen diesel scandal, these figures are recorded in a very limited part of the flight envelope - I don’t think they give a particularly useful feel for loud a helicopter is in practice (its a huge driver of when a pilot or automatic system must increase NR for landing by the way). I live near a Bell 429 base and work around EC135 and the 135 is much quieter. You can hear the 429 coming from a long way away (mostly tail rotor from the pitch).