Text in force at CS27-10: from CS27-10, effective 8 Feb 2023.
(a) reserved (b) For rotorcraft with a certification basis established prior to 1 May 2001 (1) The maximum passenger seat capacity may be increased to eight or nine provided compliance is shown with all the airworthiness requirements in effect from the initial issue of CS-27. (2) The maximum weight may be increased to greater than 2 722 kg (6 000 lbs) provided -
(i) The number of passenger seats is not increased above the maximum number previously certificated; or
(ii) Compliance is shown with all of the airworthiness requirements in effect from the issue of CS-27.
ED Decision 2023/001/R · Source