John Perschbacher

1. Paragraphs 36.11(c)(1) & (2) addressing changes in type designs for Stage 2 helicopters are confusing as written with two “musts” sandwiching an “or”. Changes in type design to Stage 2 helicopters must, at a minimum, meet the Stage 2 requirements as noted in paragraph (1), but stepping up to Stage 3 requirements per paragraph (2) should be optional. The text in paragraph (2) should read as: “(2) A helicopter may, at the option of the applicant, meet Stage 3 requirements after the change in type design and thereafter must remain a Stage 3 helicopter.” 2. The NPRM for Amendment 25 harmonizing Part 36 with ICAO Annex 16 specified 3.0 dB per halving of weight instead of 3.01 dB per halving of weight in determining helicopter noise limits. In Amendment 25, however, the noise limit definition reverted to 3.01 dB per halving of weight. The current Amendment proposed by this NPRM should take the opportunity to reinstate the 3.0 dB per halving of weight definition to harmonize Part 36 helicopter noise limits with the ICAO Annex 16 standard.