What was found
(CAN) DURING FLIGHT IN RAIN CONDITIONS, THE LOW ROTOR/HYDRAULIC PRESSURE WARNING HORN SOUNDED SEVERAL TIMES ALTHOUGH ALL SYSTEMS WERE OPERATING NORMALLY. FURTHER INVESTIGATION REVEALED THAT RAIN WATER WAS MIGRATING THROUGH THE CABIN VENTILATION DUCTING VIA THE INSTRUMENT PANEL AND EVENTUALLY ONTO THE AVIONICS SHELF AND ONTO PRINTED CIRCUITS THEREBY CAUSING THIS FALSE WARNING PROBLEM.