Spin the cooling fan manually to check for bearing seizure. Measure thermistor resistance at room temperature. Clean the heatsink. Unit is entering Constant Current (CC) mode prematurely.
The is a self-contained emergency power supply designed primarily for aircraft to provide critical standby power to attitude gyros and essential flight instruments in the event of a total electrical failure. Manufactured by L-3 Communications (now L3Harris) and supported by Extant Aerospace , this unit relies on sealed lead-acid batteries and requires strict adherence to its Component Maintenance Manual (CMM TP-483) to ensure flight safety. Core Maintenance Requirements ps-855b maintenance manual
The information in the maintenance manual is not just advisory; it is mandatory for legal compliance. All maintenance on the PS-855B must be performed in accordance with the latest revision of the applicable maintenance data. Any deviation from the manual's instructions must be approved by the relevant aviation authority. Spin the cooling fan manually to check for bearing seizure
Clean filters, check fan rotation, replace fan if defective. (Voltage Drop) Unstable input power source or faulty module. Unit is entering Constant Current (CC) mode prematurely