1.0 INTRODUCTION
  1.1 Purpose
  1.2 System Description
    1.2.1 System Architecture
    1.2.2 Systems Configuration
      1.2.2.1 Single System
        1.2.2.1.1 Single System/Dedicated Display/
                        Control Unit
        1.2.2.1.2 Single System/Multi-Function Display
                        System (MFDS)
      1.2.2.2 Dual System
        1.2.2.2.1 Dual System/Dedicated Display/Control
                        Unit
        1.2.2.2.2 Dual System/Multi-Function Display
                        System
    1.2.3 Unit Description
      1.2.3.1 Weight and Balance Computer (WBC)
      1.2.3.2 Calibration Memory Module (CMM)
      1.2.3.3 Dedicated Display/Control Unit (DDCU)
      1.2.3.4 Load Sensors (LS)
      1.2.3.5 Load Sensor Mounting (LSM)
      1.2.3.6 Pitch Attitude Sensor (PAS)
  1.3 Interchangeability
  1.4 Regulatory Approval
  1.5 Reliability
2.0 INTERCHANGEABILITY STANDARDS
  2.1 Introduction
  2.2 Form Factors, Connectors and Index
                        Pin Coding
    2.2.1 Weight and Balance Computer (WBC)
    2.2.2 Dedicated Display/Control Unit (DDCU)
    2.2.3 Calibration Memory Module (CMM)
    2.2.4 Pitch Attitude Sensor (PAS)
    2.2.5 Load Sensor (LS)
    2.2.6 Load Sensor Mounting (LSM)
    2.2.7 Aircraft Identification (A/C-ID)
    2.2.8 Interwiring
    2.2.9 Power Circuitry--Primary A/C Power Input
    2.2.10 Weights
    2.2.11 Cooling
    2.2.12 Environmental Conditions
3.0 SYSTEM DESIGN AND PERFORMANCE REQUIREMENTS
  3.1 General
  3.2 Operation/Function
  3.3 General System Hardware Layout
  3.4 CLASS I System
    3.4.1 Sensors
    3.4.2 Computer
    3.4.3 Calibration Memory Module
    3.4.4 Accuracy
  3.5 CLASS II System
    3.5.1 Sensors
    3.5.2 Computer
    3.5.3 Calibration Memory Module
    3.5.4 Accuracy
  3.6 System Layout
    3.6.1 Load Sensors (LS)
      3.6.1.1 Standard Sensor Requirements
      3.6.1.2 Environmental Conditions
      3.6.1.3 Interchangeability
      3.6.1.4 Self-Test
      3.6.1.5 Mechanical Performance of the Sensors
        3.6.1.5.1 Measurement
        3.6.1.5.2 External Influences
    3.6.2 Computer
      3.6.2.1 Computer Requirements and Function
      3.6.2.2 Interchangeability
      3.6.2.3 Self-Test
    3.6.3 Calibration Memory Module (CMM)
      3.6.3.1 Standard Requirements
      3.6.3.2 Self-Test
    3.6.4 Pitch Attitude Sensor (PAS)
    3.6.5 Dedicated Display/Control Unit (DDCU)
      3.6.5.1 Function and Standard Requirements
      3.6.5.2 Data Transfer
      3.6.5.3 Self-Test
    3.6.6 Calibration Remote Control Unit (CRCU)
      3.6.6.1 Function and Standard Requirements
    3.6.7 Load Sensor and Mounting Assembly
      3.6.7.1 General Design Objectives
    3.6.8 Electrical Performance
    3.6.9 Inputs-Outputs
      3.6.9.1 General Characteristics for Discrete
                        Signals
      3.6.9.2 Discrete Outputs
      3.6.9.3 Discrete Inputs
      3.6.9.4 ARINC 429 Outputs
      3.6.9.5 ARINC 429 Inputs
      3.6.9.6 Analog Inputs
  3.7 Maintenance and Fault Isolation
    3.7.1 Fault Monitoring
      3.7.1.1 First Failure Detection
      3.7.1.2 Monitor Function
        3.7.1.2.1 Central Processor Unit
        3.7.1.2.2 Computer Memory and CMM
        3.7.1.2.3 Input/Output
        3.7.1.2.4 Electrical Power
        3.7.1.2.5 Sensors
    3.7.2 Maintenance Function
      3.7.2.1 Maintainability of Sensors and Mountings
    3.7.3 Self-Test
    3.7.4 Calibration Schedule
    3.7.5 Automatic In-Flight Recalibration
ATTACHMENTS
    1 Block Diagram of Typical Configuration
                        (Single System)
    2 Block Diagram of Typical Configuration
                        (Dual System)
    3 Dedicated Display and Control Unit
                        Envelope
    4 Calibration Memory Module Envelope and
                        Footprint
    5 Pitch Attitude Sensor Envelope and
                        Footprint
    6 Sensor Attachment Dimensions for Lug
                        Installation
    7 Notes Applicable to Standard Interwiring
    8 WB Component Location
    9 System Interwiring (Single System)
   10 WBC-Interface to NLG-Sensors
                        (Single System)
   11 WBC-Interface to MLG (Single System)
   12 System Interwiring (Dual System)
   13 WBC Interface to NLG Sensors
                        (Dual System)
   14 WBC Interface to MLG Sensors
                        (Dual System)
   15 Environmental Test Categories
   16 ARINC 429 Parameter List