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
. 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.