The Research Of C919 Aircraft Noise Airworthiness Compliance Equivalent Procedures

Large aircraft C919 noise certification is an important part of the type airworthiness certification work, using equivalent procedures is an efficient measure to reduce the cost and time of noise airworthiness certification. Based on the research of jet aircraft noise airworthiness certification theory, as well as the civil aircraft noise airworthiness standard Annex 16, Volume I promulgated by ICAO, the basic principle and characteristic of noise airworthiness compliance equivalent procedures were analyzed in detail. After that, the theoretical framework of noise airworthiness compliance equivalent procedures which is applicable to jet aircraft noise certification was established; In addition, the principles and methods of equivalent flight test procedures and equivalent analysis procedures were definitely studied, whilst the preliminary technology system of compliance equivalent procedures applied to C919 aircraft noise airworthiness certification was established.Based on the aircraft noise level data obtained in the certification of certain aircraft type, the intercept flight test equivalent procedure was illuminated in detail, combined with the noise level data of related aircraft type obtained in flight test, it was shown that the intercept flight test equivalent procedure is effective in C919 aircraft noise airworthiness certification, and the critical factor is to achieve the effective equivalent intercept flight profile; On the basis of the NPD data of certain aircraft type obtained from the ANP database, the fitting method of aircraft noise NPD curve based on the least square method was studied, the results shown that using the least square method can effectively generate aircraft noise NPD curve. Eventually, taking the equivalent procedure of computing certificated noise level of a given aircraft type with variable mass as an example, the noise level data of similar aircraft types of C919, such as A320 and B737, was used to study the applicability of the relevant equivalent procedure in the noise airworthiness certification, and it was proved to be feasible in the aircraft noise airworthiness certification of A320 and B737, which can provide a reference for the C919 aircraft noise certification work.