R **ON A/C 001-049, 051-099, 101-149, 151-199, 201-299, 301-399,
 121VU COM NAV/TCAS 4SG K10 R **ON A/C ALL
 4. Procedure
_________
 Subtask 34-43-34-420-050

 A. Installation of the TCAS Computer
 (Ref. Fig. 401/TASK 34-43-34-991-001)

 (1)
 Clean the component interface and/or the adjacent area.

 (2)
 Do an inspection of the component interface and/or the adjacent area.

 (3)
 Remove the blanking caps from the electrical connectors (2).

 (4)
 Make sure that the electrical connectors are clean and in the correct condition.

 (5)
 Install the TCAS computer (1) on its rack (3) to connect the electrical connectors (2).

 (6) Engage the nuts (4) on the lugs (5) and tighten.
 Subtask 34-43-34-865-052

 B. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s): 4SG
 Subtask 34-43-34-740-050
 C. Do the BITE test of the TCAS (Ref. TASK 34-43-00-740-001).
 1EFF : ALL 1 34-43-34Page 405 1 1 Aug 01/05 1 1 1CES 1

 5. Close-up
________
 Subtask 34-43-34-860-051

 A. Put the aircraft back to its initial configuration.
 (1) Make sure that the work area is clean and clear of tool(s) and other items.
 Subtask 34-43-34-410-050
 B. Close Access R (1) Close the access door 824 (Ref. TASK 52-41-00-410-002).
 (2) Remove the access platform(s).
 1EFF : ALL 1 34-43-34Page 406 1 1 Feb 01/02 1 1 1CES 1 **ON A/C ALL

R Post SB 34-1189 For A/C 001-049,051-060,101-104,
 ENHANCED GROUND PROXIMITY WARNING SYSTEM (GPWS) - DESCRIPTION AND OPERATION
___________________________________________________________________________
 1. General
_______ (Ref. Fig. 001) The purpose of the Enhanced Ground Proximity Warning System (Enhanced GPWS) is to alert the flight crew of potentially hazardous conditions with respect to the terrain. The system achieves this objective by accepting a variety of aircraft parameters as inputs, applying alerting algorithms, and providing the flight crew with aural alert messages and visual annunciations and displays in the event that the boundaries of any alerting envelope are exceeded. Enhanced features have been added to existing basic Ground Proximity Warning Modes 1 to 5 which are the backbone of the system. Several main alerting functional areas are integrated into the Enhanced GPWC, which is a single Line Replaceable Unit (LRU). Except for basic GPWS, each function is pin selectable. The functional areas are:
 -basic Ground Proximity Warning System (GPWS) (Modes 1 to 5),
 -
Terrain Clearance Floor function (TCF),

 -
Terrain Awareness and Display (TAD) function.

 A.
 Basic GPWS Modes The basic GPWS modes generate aural and visual warnings if the aircraft adopts a potentially hazardous condition with respect to: Mode 1 - Excessive rate of descent. Mode 2 - Excessive closure rate with terrain. Mode 3 - Descent after takeoff and minimum terrain clearance. Mode 4 - Unsafe terrain clearance. Mode 5 - Descent below glide slope.

 1EFF : ALL 1 34-48-00Page 1 1 1 Config-1 May 01/05 1 1 1CES 1

 Enhanced GPWS - Enhanced Ground Proximity Warning System
 Figure 001

 1EFF : ALL 1 34-48-00Page 2 1 1 Config-1 Aug 01/02 1 1 1CES 1

 B. Enhanced Features The Enhanced GPWC includes enhanced features which complete the basic GPWS modes.
 (1)
 Terrain Clearance Floor (TCF) function The Terrain Clearance Floor (TCF) function adds an additional element of protection to the basic GPWS modes. It creates an increasing terrain clearance envelope around the intended airport runway directly related to the distance from the runway. TCF alerts are based on current aircraft location, nearest runway center point position and radio altitude. TCF is active during takeoff, cruise and final approach. This alert mode complements existing Mode 4 protection by providing an alert based on insufficient terrain clearance even when in landing configuration. TCF function generates aural and visual alert.

 (2)
 Terrain Awareness alerting and Display (TAD) function A major new feature of the Enhanced GPWS is the incorporation of the terrain awareness alerting and display functions. These functions use aircraft geographic position, aircraft altitude and a terrain data base to predict potential conflicts between the aircraft flight path and the terrain, and to provide graphic displays of the conflicting terrain, as illustrated by the block diagram. (Ref. Fig. 002) The terrain awareness alerting algorithms continuously compute terrain clearance envelopes ahead of the aircraft. If the boundaries of these envelopes conflict with terrain elevation data in the terrain database, then alerts are issued.
　
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