Garmin GPS 155 TSO Manual

The Garmin GPS 155 TSO is a certified panel-mounted GPS receiver designed for aircraft navigation, providing en route, terminal, and non-precision approach capabilities. It features a high-resolution display, comprehensive database, TSO-C129a certification, and interfaces with various avionics systems. Below are key sections for operation, installation, specifications, programming, and maintenance.

Features at a Glance

Key components: High-brightness LCD display, front-panel controls, antenna connector, data ports, power input.

Installation

Unpack and inspect contents. Ensure proper mounting location in aircraft panel.

1. Mount unit: Cut panel per template, secure with provided hardware.
2. Connect antenna: Route coaxial cable to antenna location, ensure proper grounding.
3. Connect power: Wire to aircraft bus per wiring diagram (red +, black -).
4. Connect avionics: Interface to CDI/HSI, autopilot via RS-232 as required.
5. Secure all connections and verify no pinched wires.

WARNING! Installation must be performed by qualified avionics technician. Ensure compliance with aircraft manuals and regulations.

First-Time Setup

Apply power; follow initialization prompts.

1. Initialization: Unit performs self-test and acquires satellite signals (may take several minutes).
2. Set location: If required, enter approximate position to aid acquisition.
3. Configure interfaces: Set serial port parameters (baud rate, protocol) to match connected avionics.
4. Load database: Insert data card (if applicable) or verify current database is active.
5. Verify operation: Check navigation display and CDI deflection.

CAUTION! Do not use for navigation until proper satellite acquisition and database validity confirmed.

Specifications

• Model: GPS 155 TSO
• Certification: TSO-C129a, Class A1
• Channels: 8 parallel channel receiver
• Update Rate: 1 second
• Accuracy: <15 meters RMS, 99% probability
• Velocity Accuracy: 0.1 knot RMS
• Database: Jeppesen NavData, 28-day update cycle
• Power: 10.5–33 VDC, 1.5A typical at 14V
• Operating Temp: -15°C to +55°C
• Dimensions: 6.25" W x 3.25" H x 12.5" D (mounting tray)
• Weight: 3.5 lbs (unit with tray)

Controls and Settings

Front Panel: POWER knob (push for backlight), concentric knobs for cursor control/data entry, ENT key, CLR key, direct-access keys (NAV, WPT, FPL, etc.).

Display Pages: NAV (default), WPT (waypoint info), FPL (flight plan), AUX (setup).

Settings: System setup (units, time format), interface configuration (NMEA/ARINC), CDI scaling (en route/terminal/approach), RAIM prediction, database management.

Connecting to Avionics

Interfaces via RS-232 serial ports. Typical connections: CDI/HSI (for course deviation), autopilot (for navigation steering), data link (for weather/traffic).

1. Ensure power off before making connections.
2. Use shielded cables, ground shield at one end only.
3. Configure port settings (baud rate, protocol) in AUX menu to match connected device.
4. Verify data output with system test or monitor mode.

Tip: Refer to aircraft avionics manual for specific interface requirements.

Navigation Operations

Supports direct-to, flight plans, holds, and approaches.

1. Direct-to: Press NAV, enter waypoint identifier, press ENT.
2. Flight Plan: Press FPL, create new or select existing, edit legs as needed.
3. Activate leg: From FPL page, cursor to leg, press ENT to activate.
4. Holding pattern: From NAV page, press HOLD, define fix, inbound course, turn direction, leg time/distance.
5. Approaches: Select approach from database, load into flight plan, activate when cleared.
6. CDI scaling: Automatically adjusts for en route (5 nm), terminal (1 nm), approach (0.3 nm).
7. RAIM: Check availability for approach via AUX page.

WARNING! Always verify approach suitability and RAIM availability prior to commencing approach. GPS approaches must be flown as published.

Database Management

Uses Jeppesen NavData. Database expires every 28 days; must be current for IFR operations.

Update Procedure: Obtain new data card from Jeppesen. Power off unit, insert card into slot (if equipped), power on, follow prompts to load. Verify effective date on AUX > STATUS page.

CAUTION! IFR GPS navigation requires current database. Using expired data for IFR is prohibited.

Care & Maintenance

Exterior cleaning only. Use dry, soft cloth. Do not use solvents or sprays.

Preventive Maintenance: Check antenna and cable connections for security, corrosion. Verify database currency. Perform periodic self-test (from AUX page).

CAUTION! No user-serviceable parts inside. Refer servicing to qualified Garmin-authorized facility.

Regulatory Information

TSO-C129a certified. Complies with FAA requirements for IFR en route, terminal, and non-precision approach operations when installed per Garmin installation manual. Copyright © Garmin Ltd. or its subsidiaries. For technical support, contact Garmin Aviation Support at 1-800-800-1020 or visit www.garmin.com.

Troubleshooting

Reset: Power cycle unit. For persistent issues, perform master reset via AUX menu (note: erases user waypoints and settings).

Service: Contact Garmin Aviation Support 1-800-800-1020 or authorized service center.