Radar Altimeter AN APN-171(V) for PODCAST 002

Slide 1:

CENTER FOR NAVAL AVIATION TECHNICAL TRAINING MARINE UNIT NEW RIVER CH-53E Radar Altimeter System AN/APN-171(V)

INTRODUCTION:

INTRODUCTION The Radar Altimeter System provides a reliable means of informing the pilot and copilot the helicopter’s altitude above the terrain. The system interfaces with several other systems to provide them with altitude signals as a reference.

LEARNING OBJECTIVES:

LEARNING OBJECTIVES As a 6323 CH-53 Avionics Technician these Learning Objectives are important for you to learn. You will be expected to know how to accurately perform a functional check of the system, analyze and troubleshoot the discrepancy, then repair the fault. Before you can do that, you need to know contents of this PODCAST.

LEARNING OBJECTIVES:

LEARNING OBJECTIVES At the conclusion of this PODCAST, you will be able to: DISCUSS the purpose and description of the Radar Altimeter System. IDENTIFY the location of Radar Altimeter System components.

PURPOSE :

PURPOSE The AN/APN- 171(V) Radar Altimeter System provides both pilots with a constant visual indication of absolute altitude measured between 0 and 5000 feet above the terrain.

DESCRIPTION :

DESCRIPTION The system processes the time between a transmitted burst of radar energy and the reflected returned energy into an altitude measurement. This measurement is supplied to the Automatic Flight Control System and the Landing Gear Warning System.

COMPONENTS :

COMPONENTS Receiver/Transmitter Located in the right electronics compartment

COMPONENTS :

COMPONENTS Receiver/Transmitter sends a signal to the transmit antenna and measures the time before receiving the reflected signal on the receive antenna to determine the altitude.

COMPONENTS :

COMPONENTS Receiver/Transmitter also sends this information to the Altitude Indicators, AFCS and Landing Gear Warning System.

COMPONENTS :

COMPONENTS Altitude Indicators There are 2 Altitude Indicators located on the instrument panel

COMPONENTS :

COMPONENTS Altitude Indicators Displays altitude and low level warning information

COMPONENTS :

COMPONENTS OFF Flag - provides a visual indication when system is warming up, aircraft is above 5000 feet or signals are unreliable. Altitude Indicators Controls

COMPONENTS :

COMPONENTS NO TRACK MASK - Hides the altitude needle when system is warming up, the helicopter is above 5000 feet or signals become unreliable. Altitude Indicators Controls

COMPONENTS :

COMPONENTS Altitude Indicators Operation Rotating the PUSH-TO-TEST Knob will TURN-ON the system

COMPONENTS :

COMPONENTS Altitude Indicators Operation With the System “ON” OFF Flag (Barber Pole) goes out of view Low Level Warning Index appears LOW Light illuminates

COMPONENTS :

COMPONENTS Rotating the OFF/SET Knob will move and set the Low Level Warning Index to the desired altitude. Altitude Indicators Operation With the System “ON”

COMPONENTS :

COMPONENTS Pushing the OFF/SET Knob will energize a self test function in the Receiver / Transmitter that will cause the Altitude Indicator to display an altitude of 100 ± 15 feet Altitude Indicators Operation

COMPONENTS :

COMPONENTS Altitude Indicators Operation Low Altitude Warning Light - Illuminates when the altitude needle is at or below the setting of the Low Level Warning Index With the System “ON”

COMPONENTS :

COMPONENTS Altitude Indicators Operation Low Altitude Warning Light - extinguishes when the altitude needle moves above the setting of the Low Level Warning Index With the System “ON”

COMPONENTS :

COMPONENTS Antennas Located in the fuselage under the left and right electronics compartments

COMPONENTS :

COMPONENTS Antennas The left antenna is used to receive The right antenna is used to transmit

SUMMARY :

SUMMARY This PODCAST was developed as a Training Aid for you. Self-assessment of the Learning Objectives are your responsibility. The Learning Objectives are satisfied when you can accurately discuss the purpose and description of the AN/APN-171(V) Radar Altimeter System; and locate the system’s components on the CH-53E Helicopter.

Slide 23:

Thank you for listening and completing this PODCAST, if you have questions or comments please e-mail them to robert.adelsperger@navy.mil