A thorough maintenance manual does not just list steps; it explains the how and why. Here are the key features and operational principles of the PS-855B, which you must understand to properly service it.
Regular maintenance for the Challenger MT855B includes checking and changing:
[Normal Flight Operation] ──> Supplies 28 VDC trickle charge to battery pack │ (Essential Bus Failure) │ ▼ [Automatic Relay Transfer] ──> Instantly provides 24 VDC & 5 VDC backup power Manual Testing with a Stopwatch Connect the unit to an approved manual test station. Move the selector switch into the position. Click a stopwatch to begin timing the drain cycle.
Visually inspect large electrolytic capacitors for bulging tops or leaked crust. Measure capacitance and ESR value; replace if out of spec. Faulty current control circuit or open driver transistor.
to identify the correct part number (501-1712-02) if a replacement is required. PS-850/PS-855 Component Manual | PDF - Scribd ps-855b maintenance manual
Shows oscilloscope patterns at key nodes (gate drive, transformer secondary, feedback pin). A missing waveform tells you where the fault lies.
Provides 5 VDC output for critical standby electronics.
A detailed guide to ordering replacement components from Avionics Systems. 4. Troubleshooting and Safety Tips
Utilize approved safety glasses, gloves, and protective clothing. A thorough maintenance manual does not just list
Wait a minimum of five minutes after disconnection to allow internal high-voltage capacitors to fully discharge. Protective Gear
In the demanding world of aviation, where reliability and safety are paramount, the equipment on board must be kept in peak condition. This is especially true for critical systems like emergency power supplies. For the L3Harris PS-855B, a key component in many aircraft, its proper maintenance is not a matter of routine—it is a matter of safety.
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later.
: Detailed product data, including voltage outputs and weight for the PS-855B, can be found at Seaerospace . TP 483 - PS 850 PS 855 - Rev.B | PDF | Electricity - Scribd Move the selector switch into the position
Recalibrate electronic sensors for precise operation. 4. Troubleshooting Guide
: Steps to identify failures in the internal charging circuit, battery packs, or 5 VDC converter.
If an original component is obsolete (e.g., Fairchild KA3842 PWM), the manual may list direct substitutes (e.g., TI UC3842). Always check the “Alternative Parts” addendum.
Slide the cover backward by 2 centimeters, then lift it vertically off the chassis pins. Servicing the Primary Filter Assembly Locate the filter housing near the lower intake manifold.