Deterrent buffet or not? Quantifying buffet on flight test aircraft

Thomas J. EsserM, The Boeing Company (USA)
Dr. Jia Luo, The Boeing Company (USA)

Abstract

Part 25 regulations rely on the pilot’s judgement to determine when an aircraft reaches deterrent buffet. Large certification programs that occur over a long period of time and involve numerous pilots can introduce a significant amount of variability in the deterrent buffet dataset.

Having a clear baseline and an objective reference with which buffet can be measured and discussed onboard the aircraft can bring consistency and an increased understanding of flight test findings. This paper discusses a novel method for quantifying buffet that takes into account multiple factors including intensity, frequency, and direction that influence human body response to buffet vibration. When combined with a robust set of pilot buffet determinations derived from numerous aircraft models these algorithms enable the test crew to have informed conversations about what they are seeing on the aircraft.

TOBI, the Tool for Onboard Buffet Identification, has improved safety and efficiency by turning raw data into actionable information. This allows for flight crews to have informed discussions about their test results and determine the most appropriate path forward. Originally intended for stall and windup turn testing, the capability to quantify buffet onboard the aircraft has opened up a variety of other uses and continues to improve test conduct by giving engineers and pilots the timely information they need to make informed decisions onboard the aircraft.