STRUCTURAL INTEGRITY RECORDING SYSTEM FOR HELICOPTERS

The Structural Integrity System (SIRS) is being developed to permit the determination of helicopter usage spectrum on an aircraft by aircraft basis. Knowledge of the usage spectrum is required if realistic fatigue lives of helicopter dynamic components are to be calculated. Existing fatigue life methodology uses an assumed usage spectrum in the calculation. This causes early removal of components on mildly used aircraft. Conversely, severe usage may be undetected and result in a premature failure. The SIRS includes an onboard recorder, a data retrieval unit, and a Fatigue Damage Assessment (FDAS) math model. Data can be retrieved on a scheduled basis or on demand as the situation warrants. The usage data is used to recalculate fatigue lives using FDAS and scheduled replacement times adjusted according to actual usage.