Ps-855b Maintenance Manual

The maintenance manual includes a matrix of common faults, probable causes, and remedies. Key entries include:

Symptom: System will not build pressure

The PS-855B is an Emergency Power Supply (EPS) manufactured by L3Harris (formerly JET/L-3 Communications) that provides backup power to attitude gyros and other critical avionics during a total aircraft power failure. Maintenance for this unit is primarily governed by the Component Maintenance Manual (CMM) TP-483, which includes an Illustrated Parts List (IPL). Primary Maintenance Manual: TP-483

The PS-850/PS-855 Component Maintenance Manual (TP-483) is the official technical guide for qualified personnel to install, repair, and maintain the unit.

Revision Status: Revision B (dated July 30, 2014) is a widely cited version. ATA Chapter: Typically found under ATA 24-30-08.

Scope: Covers installation guidelines, operational functional checks, troubleshooting, and detailed repair procedures. Key Maintenance Requirements

Regular upkeep focuses on the unit's rechargeable, sealed lead-acid battery packs.

Periodic Battery Checks: According to L3 Service Letter SL-170, the battery condition must be checked every 3 to 6 months.

Recharging: The unit automatically maintains a charge from normal flight operations and can reach 50% capacity within one hour at 25°C.

Testing: Includes a temperature-compensated battery capacity test that can be performed under load from the cockpit or at the unit itself. Necessary Maintenance Equipment

Performing the procedures in the manual requires specific specialized tools and materials:

Test Panels & Load Resistors: Specific models are required to simulate aircraft loads during bench testing.

Consumables: The manual lists required adhesives, tapes, and protective coatings for internal repairs. Core Specifications for Maintenance PS-855B Specification Input Power 28 VDC, 15 Amps Output Voltage 24 to 28 VDC (Emergency) & 5 VDC (Converter) Battery Capacity 5.0 Amp/Hour (higher than the 2.5 Ah on A/C models) Weight 13.7 lbs max Service Life Unrestricted, provided periodic checks are passed

For formal maintenance or repair, you should consult an authorized repair station like Duncan Aviation or Southeast Aerospace, as they maintain current service literature and TSO compliance. L3Harris PS-855B | SEAEROSPACE.COM

The manual’s parts list specifies low-impedance or low-ESR capacitors (e.g., Rubycon ZLH, Nichicon HE). Using general-purpose caps leads to overheating and short life.

If you succeed in repairing or maintaining the PS-855B, document:

This becomes your custom manual.

WARNING: RISK OF ELECTRIC SHOCK Ensure power is disconnected before servicing electrical components.

WARNING: PRESSURIZED SYSTEM Do not remove the switch from the pressurized line without isolating the system and relieving pressure. Sudden release of pressurized fluid can cause serious injury.

CAUTION:

If you must repair the unit without a manual:

For a standard switched-mode power supply (SMPS), these steps are universal:

Dispose of the PS-855B in accordance with local environmental regulations. Separate metal components from electrical waste.

End of Document

The PS-855B 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

Maintenance for the PS-855B is governed by L3 Service Letter SL-170, which outlines the mandatory periodic checks and testing intervals.

Periodic Checks (Every 3 to 6 Months): A condition check must be performed every quarter or half-year to verify the unit's operational status. This is similar to a "Preflight Check" and ensures the unit is ready for emergency deployment.

Annual Capacity Testing: Once a year, a full battery capacity test is required to determine the remaining life of the cells. Essential Maintenance Procedures

According to the PS-855B documentation on Scribd, technical personnel should follow these specific steps: Capacity Check (The 5-Second Test):

With no external power applied, press and hold the PUSH TO TEST button for 5 seconds.

If the Test LED stays illuminated for the full 5 seconds, capacity is above 50%.

If the LED fails to illuminate or stays on for less than 5 seconds, the capacity is below 50% and requires a full recharge cycle. Recharging Guidelines: Above 50% Capacity: Charge for 8 hours. Below 50% Capacity: Charge for 16 hours.

The unit can reach 50% capacity within one hour at 25°C under normal flight conditions. Storage and Environmental Care:

Batteries must never be left in a discharged state, as this causes permanent damage.

Ideal storage is below 29°C (85°F) to minimize self-discharge. Technical Specifications for Maintenance Specification Input Power 28 VDC, 15 Amps max Output Voltage 24-28 VDC (Main) and 5 VDC (Converter) Battery Type Sealed Lead Acid (5.0 Amp/Hour for B model) Weight 13.7 lbs max Standard Manual TP-483 (Component Maintenance Manual) Procuring the Manual and Parts PS-850/PS-855 Component Manual | PDF - Scribd ps-855b maintenance manual

The PS-855B (P/N 501-1712-02) lead-acid emergency power supply, manufactured by L3Harris/Avionics Systems, requires regular maintenance guided by CMM TP-483 and Service Letter SL-170, including visual checks for outgassing and annual capacity tests. Essential procedures involve a 5-second push-to-test for capacity, a 7.0-ohm load test for 48 minutes, and specific 8 to 23-hour recharging requirements to ensure continued airworthiness. For detailed procedures, refer to the L3Harris CMM TP-483 documentation at seaerospace.com Southeast Aerospace Inc. L3Harris PS-855B | SEAEROSPACE.COM

The TASKI Swingo 855B walk-behind auto-scrubber requires daily cleaning of the recovery tank, squeegee blades, and suction filter to maintain functionality. Regular maintenance includes checking battery electrolyte levels and inspecting mechanical parts for wear, with essential component replacements listed in the technical documentation. Detailed technical parts and service information can be found at Scribd. TASKI Swingo 755B & 855B Parts List | PDF - Scribd

The PS-855B (and its predecessor, the PS-850) is an Emergency Power Supply (EPS) system commonly used in aviation to provide backup power for critical flight instruments. Proper maintenance is vital for ensuring these units function during a power failure.

Below is a blog post template summarizing the key maintenance requirements found in the PS-850/PS-855 Maintenance Guide.

Keeping the Lights On: A Guide to PS-855B Emergency Power Supply Maintenance

In the cockpit, "emergency" is a word you never want to hear, but it's the one you must always be prepared for. For many aircraft, the L-3 Communications (now ACSS/L3Harris) PS-855B is the silent guardian that keeps your attitude indicators and emergency lighting alive when everything else goes dark.

However, an emergency power supply is only as good as its last maintenance check. Here is what you need to know about the PS-855B maintenance manual and keeping your unit flight-ready. 1. The Core of the System: Battery Health

The PS-855B relies on internal sealed lead-acid or nickel-cadmium batteries. Unlike your car battery, these require specific periodic attention to prevent "memory" issues or capacity loss.

Periodic Checks: According to the Maintenance Guide, batteries should undergo a physical condition and functional check every 3 to 6 months.

Outgassing & Storage: If the unit is stored for long periods, it must be recharged periodically to prevent permanent cell damage. 2. Essential Maintenance Procedures

The PS-850/PS-855 Installation and Operation Manual outlines several critical service steps:

Preflight Check: A simple cockpit test to ensure the "In-Use" or "Battery" lights trigger correctly.

Capacity Test: This is the most crucial maintenance step. It involves a timed discharge to ensure the battery can sustain the rated load for the required duration (usually 30 or 60 minutes, depending on the aircraft's certification).

Visual Inspection: Checking for cracked housings, leaking electrolyte, or corroded connector pins. 3. Qualified Service Only

It is important to note that while pilots perform the preflight, actual repairs and internal maintenance must be done by qualified personnel in accordance with FAA or local regulatory standards. The PS-855 Component Manual provides the specific electrical tolerances and assembly diagrams needed for bench testing. Why It Matters

A neglected PS-855B might show a "green" light during a quick preflight but fail five minutes into a real emergency. Regular adherence to the service literature ensures that when the master switch fails, your emergency instruments don't.

You can often find reference versions on platforms like Scribd, but always ensure you are using the latest revision approved for your specific airframe.

PS-855B Maintenance Manual

Table of Contents

1. Introduction

The PS-855B is a high-performance [insert type of equipment, e.g. power supply, amplifier, etc.]. This manual provides maintenance and repair information for the PS-855B. It is intended for trained technicians and engineers responsible for maintaining and repairing this equipment.

2. Safety Precautions

Before performing any maintenance or repair, ensure that you have read and understood the following safety precautions:

3. Maintenance Schedule

The following maintenance schedule is recommended for the PS-855B:

4. Troubleshooting

This section provides guidance on troubleshooting common issues with the PS-855B:

5. Component Replacement

This section provides instructions for replacing components:

6. Adjustments and Alignments

This section provides instructions for adjusting and aligning the PS-855B:

7. Electrical Diagrams

The following electrical diagrams are provided:

8. Parts List

The following parts are used in the PS-855B:

Ps-855b Maintenance Manual

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