The Study On Test Method For Aircraft Noise Equivalent Flight

The noise data of three measurement points need to be obtained in the process of the new aircraft noise airworthiness certification.The minimum number of samples per measurement point is six,according to the Noise Standards: Aircraft Type and Airworthiness Certification.In order to ensure the validity of the data,it is necessary to have a large number of samples,and the aircraft needs to carry out many flight tests.In order to reduce the cost of airworthiness certification,based on the Airworthiness Regulations,the noise data of three measuring points of a plane are analyzed and the equivalent flight track approved by airworthiness regulations is obtained.Flight tests carried out in accordance with the equivalent flight procedures will reduce the cost of airworthiness certification and shorten the time for airworthiness validation.Based on the original 1/3 octave bandwidths sound pressure level data of DC9 aircraft,the noise data of 10 dB drop interval are calculated.The standard Take-off and landing procedure of the European Civil Aviation Conference is adopted,and the standard track of aircraft landing is obtained by reference to ANP database.The position of the starting point and end point of the 10 dB descending interval in the track is obtained by comparing the flight time and noise measurement time.When pilots fly aircraft for airworthiness tests,they can fly according to the proposed flight path.Enter the standard flight path from the point of entry and leave the flight path from the point of departure.The equivalent flight path diagram is between the entry point and the departure point.According to the noise data obtained in this flight test,the noise in the equivalent flight track segment is tested and the effective noise level is calculated,which is the same as the original calculated value.DC9 and C919 similar,are dual-turbo fan single channel aircraft,in accordance with the Airworthiness Regulations,C919 noise airworthiness certification work can reference in this paper to obtain the equivalent flight track method.