Originally Posted by
BDAttitude
I think not correct.
INTLK coming from the right side is a sensing channel activated upon switching K2 by applying 14V+ to A/P TRIM SPEED HIGH.
You can probably clarify this by posting wiring diagram 22-13-11.
Been digging around and I've had some luck. I've gotten a hold of schematic 22-13-11 to fill in some detail. I tried taking a full size snapshot, but it gets too fuzzy to read when I zoom out. I think I can post the relevant parts though.
First I'll repost the original schematic:
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Schematic 27-41-11
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The bold line dark box on the right represents the entire stab trim motor and associated controllers. I'm told this is a one piece unit. Zoomed in:
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Trim motor detail
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The "INTLK" in and out in this diagram are actually related to the autopilot speed selection. The MAIN ELECT TRIM INTLK function is a signal from the MAIN TRIM ARM RELAY directly to each of the FCC's. Here is the relevant detail from schematic 22-13-11:
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Main Trim Arm Relay to FCC detail
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This diagram has a reference to another schematic 22-11-11 for the FCC, but I've had a peek at that one and it doesn't provide any clarity as to what happens to the MAIN ELEC TRIM INTLK signal.
The other detail from 22-13-11 that corresponds to the lines coming out the right side of 27-41-11 is here:
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Automatic Trim Input Detail
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Unfortunately, all of this detail still does not tell us what happens if the FCC does not correctly process the MAIN ELEC TRIM INTLK signal.
Both the Main and Automatic trim signals are sent to the stab trim motor Controller. I could find no information regarding this component, which again, I am told is housed within the motor assembly itself. The motor is made by Eaton and is similar to the one on the 737NG. If a malfunction in the FCC allows simultaneous signals from the Automatic and Main Electric trim to arrive at the Controller, then that might explain the reported test results - just speculating here.
Again, this should be caveated that the tests involved the new FCC software and do not necessarily reflect conditions on the accident aircraft.