Low-frequency flight control system oscillatory faults prevention via horizontal and vertical tail load monitors
The Tail Load Monitoring System detects faulty low frequency (e.g. those in the range from 0.1 to 1 Hz) oscillatory conditions caused by Flight Control System malfunctions while the aircraft is in air by means of a continuous assessment of the estimated tail load behavior and data processing. Both estimation and data processing activities are provided by a dedicated architecture featuring a tail load estimation module, a band-pass filter and three independent paths that continuously monitor nuisance fault detection events avoidance, catastrophic events avoidance (addressing a limit load criterion), and structural damage avoidance (addressing fatigue life criteria).
1. A method for detecting faulty low frequency persistent oscillations signals generated by a Flight Control System malfunction that causes faulty persistence aircraft surface oscillations comprising:
sensing flight parameters including the group consisting of Yaw Rate, Roll Rate, Pitch Rate, Angle of Attack Rate, Angle of Attack, Sideslip Angle, Mach Number, Airspeed, Dynamic Pressure, Flap Angle, Slat Angle, Horizontal Stabilizer Position, Rudder Position, and Elevator Position;
computing a tail load estimate signal by means of formulae and tables whose inputs are said flight parameters;
submitting said tail load estimate to a band-pass filter to provide a filtered tail load estimate signal;
integrating said filtered tail load estimate signal with a first integration function to provide a first integration result, with a second integration function to provide a second integration result and with a third integration function to provide a third integration result;
comparing said first integration result with a first threshold; comparing said second integration result with a second threshold; comparing said third integration result with a third threshold; and detecting an oscillatory fault occurrence as per each of said comparisons.
2. The method of claim 1 wherein said first integration result and associated comparison reveals nuisance fault detection events avoidance.
3. The method of claim 1 wherein said second integration result and associated comparison reveals catastrophic events avoidance addressing a limit load criterion.
4. The method of claim 1 wherein said third integration result and associated comparison reveals damage addressing fatigue life criteria.
5. The method of claim 1 wherein said detecting ensures oscillations remain smaller than the aircraft oscillatory envelope.
6. The method of claim 1 wherein said reliably detecting detects fatigue life consumption and limit load-reaching events.
7. The method of claim 1 wherein said reliably detecting avoids nuisance fault detection events.
8. The method of claim 1 wherein said detecting is based on flight data other than surface oscillations.
9. The method of claim 1 wherein said detected low frequency oscillations are in the range of 0.1 Hz to 1 Hz.