What Is Negative Acceleration?
China Civil Aviation Regulations, Airworthiness Standards for Transportation Aircraft stipulates that when the aircraft is flying at negative acceleration within the envelope, the power unit, auxiliary power unit, or any component or system related to the power unit or auxiliary power unit must A dangerous fault has occurred.
Negative acceleration
Right!
- Chinese name
- Negative acceleration
- Regulations
- Airworthiness Standards for Transportation Aircraft
- Related parts
- Power unit, auxiliary power unit
- Procedure
- Adjust the amount of oil to the minimum before taking off
- China Civil Aviation Regulations, Airworthiness Standards for Transportation Aircraft, stipulates that when the aircraft is flying at negative acceleration within the envelope, the power unit, auxiliary power unit, or any component or system related to the power unit or auxiliary power unit must not A dangerous fault has occurred.
- The zoom-in envelope of civil aircraft is usually designed to be -1g ~ 2.5g. The overload during normal flight is usually around 1g. However, under certain circumstances, the aircraft may need to fly with negative acceleration. The additional speed test flight is in law. Fly in the range of -1g ~ 0g overload to verify that each airborne system can work normally [1] .
- 1 Flight test methods and procedures
- 1.1 Flight test method
- AC25-7A " Flight Test Guide for Certification of Transport Category Airplanes" recommends that the aircraft should be operated at the critical fuel and lubricant levels, the maximum continuous thrust of the engine, and the auxiliary power unit working under normal load conditions within the flight envelope. Fly with a critical negative acceleration. The duration of each test point between -1g and 0g is at least 7s, and the cumulative negative acceleration flight time is not less than 20s.
- 1.2 Flight Test Procedure
- 1) Adjust the amount of experimental engine oil to the minimum available oil amount before take-off;
- 2) The aircraft is trimmed at a fixed altitude and maintains a stable level flight. The fuel quantity is adjusted so that the left and right fuel tanks are in a balanced state. The double engine works at the maximum continuous thrust state. The level flight speed increases to the target airspeed, and then the rod is pushed slowly. Use parabolic flying hair to perform negative acceleration flight, and gradually make the normal overload reach -1g ~ 0g, and continue for 3s ~ 5s, perform negative acceleration action training, and adjust the training times as needed.
- 3) Adjust the fuel volume of the left and right fuel tanks to half the fuel tank (the fuel volume of the left and right fuel tanks must be balanced), level the flight at the specified altitude, and double engine work at the maximum continuous thrust state. The plane's level flight speed will increase to the target airspeed. Slowly push again, and use the parabolic flight method to perform negative acceleration flight, so that the normal overload reaches -1g ~ 0g, and lasts for more than 7s, but not more than 10s, repeat the above operation twice.