Ground Vibration Test at National Test Pilot School

Pilots at the National Test Pilot School are conducting a Ground Vibration Test (GVT) on an Aermacchi MB-339, a military jet trainer and light attack aircraft, to analyze its dynamic behavior under varying conditions. The test utilizes the high channel Spider-80Xi system with the EDM Modal suite to perform the Ground Vibration Test. Seven accelerometers capture the aircraft's response, while a modal shaker excites the structure, enabling the measurement of frequency response functions (FRF). A Burst Random excitation method is applied, and the data is processed using the p-LSCF frequency domain curve-fitter (Poly-X) to determine the aircraft’s modal parameters accurately.

Some pictures and results from the experiment are illustrated below.

Aermacchi MB-339 Ground Vibration Test
modal shaker in ground vibration test
ground vibration test
ground vibration test
ground vibration testing

Ground Vibration Tests (GVT) are conducted to assess aircraft flutter and establish a safe flight envelope before takeoff. The results from these experimental modal tests are also essential for correlating and validating simulation model outcomes. As such, GVT is a critical step in the aircraft development and assembly process.

Crystal Instruments’ Ground Vibration Testing system is efficient in handling these complex modal tests.

Aakash Umesh Mange - Senior Application Engineer