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  • Mark created a new forum post in ATA 31 Instruments
    Inbound write-up:

    At 8500' with gear up in a clean configuration and throttles at idle, red "Gear Not Down" and "Gear Disagree" EICAS warnings for approximately 30 seconds. 
      
      
       
         (A larger image can be found  here . Schematics Manual 31-51-04.) 
      
      
    So what's going on here???

    If the aircraft "thinks" you're in landing configuration, but the gear is not down..... it's going to let you know about it.

    The warning circuit is looking at three basic conditions. Throttle position, flaps/slats position, and radio altimeter inputs.

    One biggie for a warning is the aircraft below 800' radio altitude and the gear not down. Our write-up didn't fall into this condition.

    What we found for this particular write-up was a logged slat position sensor error in the Proximity Unit's fault history.

    The logic saw this as "the throttles are at idle", "flaps/slats are NOT in a clean wing condition", and "the gear is not down." 

    We found the faulted slat position sensor target with a gap beyond tolerance. Once adjusted..... no more issues have occurred.
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  • Same concept used for "Wheel Well Fire Loops"
    Only one aircraft checked, but I had about 330ohms across pins 15 and 16 at fire test panel.
      
      
      
     
      
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  • Mark replied to the topic Emergency Lights in ATA 33 Lights
    Bent down...... They had to be carefully straightened out (with power removed from charger).
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  • Mark created a new forum post in ATA 49 - APU
    APU was not starting. History stated that it would make approximately 30% and shutdown. I didn't try a start in the failed condition.

    The ECU was showing a inlet door failure.
      
      
     
      
      
    The ECU needs to receive a ground signal indicating the inlet door is open. I'm surprised a start would be initiated with the door not showing fully open.

    I "fooled" the system and had a successful start.

    Looking at the schematic.....
      
      
     
      
      
    If you pull relay K176 and jumper B2 (28 VDC) to B1 (door actuator "open" coil), you can command the door to open. (B2 to B3 will close it.)
      
      
     
      
      
    With the door open, relay K547 should be energized which provides the ground signal to the ECU on pin 2. I visually verified the door was open and jumped pin 2 to ground.
      
      
     
      
      
    With the good start, the only conclusion would be a bad or malfunctioning door sensor. This switch is made when a magnetic target is in close proximity.

    The switch can be verified as good or bad by checking for a ground at pin 7 of K547 with the door open.

    I didn't see the issue first hand, but there was a busted rivet on the target. Along with a target gap that was over limits.
      
      
     
      
      
     
       
     
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  • Mark created a new forum post in ATA 33 Lights
    Aircraft just out of "C" check. A couple emergency lights inop.....

    Dropped the overhead battery storage panel and just stared for a second.

    Is that what I think it is????
      
      
     
      
      
     
      

    The pins from the charger are supposed to go "in" the sockets on the battery...... not underneath them.

    I'm not quite sure how the battery was even installed this way.
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