C919 Empennage Vibration Test
Project name: C919 Empennage Vibration Test
The empennage of an aircraft plays a crucial role in overall stability, control, and flight safety. Any deficiencies in its vibration performance can lead to unexpected flutter, reduced control authority, or structural fatigue. In March 2024, our company conducted a comprehensive vibration test of the C919 aircraft empennage using our self-developed DE-series multi-channel dynamic signal acquisition system. The testing program included synchronous data acquisition across 96 measurement points, providing a full-field characterization of the tail section's dynamic behavior.
Technical Highlights
The DE-series system enabled high-density measurement with 96 fully synchronized channels, ensuring all critical locations were monitored simultaneously. The sampling rate was set at 20 kHz, covering the full modal bandwidth from 0 to 5 kHz, which allowed accurate capture of high-frequency responses and transient vibration events. Accelerometers were strategically positioned on key structural members, including the vertical stabilizer, horizontal stabilizer, and control surface attachment points, to capture both bending and torsional vibration modes.
Key Test Parameters
The primary objectives were to verify the natural frequencies of the empennage within the expected 5–80 Hz range and assess damping ratios, with target damping coefficients below 0.05 to ensure adequate vibration attenuation. Mode shape reconstruction was performed, and correlation was evaluated using the Modal Assurance Criterion (MAC), with all key modes achieving MAC values of 0.9 or higher, demonstrating excellent agreement with the theoretical predictions.
Airworthiness Compliance
The test confirmed that the C919 empennage meets CCAR-25.629 flutter requirements, validating that the design maintains a ±15% margin from predicted critical vibration modes. The results provide essential data for structural health monitoring, flight control tuning, and predictive maintenance planning.
Conclusion
The vibration test successfully verified the dynamic performance of the C919 empennage, confirming its structural integrity and compliance with airworthiness standards. The high-resolution data collected will support further design optimization, fatigue analysis, and certification processes, ensuring safe and reliable operation of the aircraft under a variety of flight conditions. By leveraging high-density, synchronized measurement technology, this testing program sets a benchmark for future aircraft empennage validation.
