(5)  
Parking Brake System (Ref 32-44-00)

 B.  Aural Warning System
 (1)  
The components of the aural warning system that interface with the altitude alert system are the MAWEA and the aural warning speakers.

 (2)  
MAWEA

 (a)  
The MAWEA is an assembly containing printed circuit cards that receive and process inputs from various airplane systems to detect warning conditions and generate aural and visual warnings. The crew alerting card is one of the printed circuit cards in the MAWEA.

 (b)  
The MAWEA printed circuit cards that interface with the altitude alert function of the crew alerting card are the master monitor cards, the signal collection/tail ID card #1, and the aural synthesizer cards.

 (c)  
Two master monitor cards provide inputs to the crew alerting card that control the altitude alert logic. These inputs are flaps in landing range and landing gear down and locked.

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 (d)  
The signal collection/tail ID (SCID) card #1 processes analog discretes including the altitude alert inop output from the crew alerting card for transmission on an ARINC 429 data bus.

 (e)  
Two aural synthesizer cards (ASC) process outputs from the crew alerting card to generate the level B owl caution aural and the approach advisory C chord aural.

 (f)  
The MAWEA is located in the right crawlway at STA 348, WL 153, RBL 25.

 (3)  Aural warning speakers
 (a)  
Two aural warning speakers are used to broadcast the aural tones generated by the aural synthesizer cards in the MAWEA.

 (b)  
The captain's and first officer's aural warning speakers are located overhead in the flight deck.

 C. Air Data System
 (1)  
The components of the air data system that interface with the altitude alert system are the:

 (a)  
Air data computers (ADC)

 (b)  
AIR DATA SOURCE SELECT switches

 (c)  
ADC source select relays

 (2)  
Air data computers

 (a)  
Three ADC's provide baro-corrected altitude to the crew alerting card on output data bus #2. The left or center ADC provides data to input port A, the right or center ADC provides data to input port B.

 (b)  
The left and center ADC's are located in the main equipment center rack E1. The right ADC is located in the main equipment center rack E2.

 (3)  
AIR DATA SOURCE SELECT switches

 (a)  
The captain's AIR DATA SOURCE SELECT switch provides a ground discrete to the crew alerting card that is used along with the MCP bus input to select the baro-corrected altitude input port.

 (b)  
The captain's AIR DATA SOURCE SELECT switch is located on the captain's source select module on panel P1.

 (4)  
ADC source select relays

 (a)  
Two ADC source select relays switch the ADC data bus #2 outputs. The captain's ADC source select relay switches the left and center output busses. The first officer's ADC source select relay switches the right and center output busses. The relays are interlocked so that only the captain or the first officer can select the center ADC at one time.

 (b)  
The ADC source select relays are located in the electrical and electronics compartment above the main equipment center.

 D. Autopilot/Flight Director
 (1)  The component of the autopilot/flight director that interfaces with the altitude alert system is the autopilot flight control system (AFCS) mode control panel.
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 (2)  AFCS mode control panel (MCP)
 (a)  
　
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