Originally Posted by
tdracer
Loma, first off I'd be surprised if the reverser moved much - there are locking actuators that shouldn't unlock in the absence of hydraulic pressure. The stowed prox sensors may go 'target far', but the actual reverser movement would be small.
Now, on Boeing, it takes more than 'unlocked' for a thrust cutback - the thrust cutback is based on the FADEC sensed actual reverser position (there is some special logic that comes into play if the sensed position is different between the channels). Typically nothing happens until the reverser is more than 10% from the commanded position. For example, if closed is 0%, thrust cutback will start at 10% and limited to idle at 15% - same thing at the other end between 85% and 90% deployed.
Now, as noted, that's how the Boeing installation works, but I'd be a bit surprised if Airbus is much different.
Thanks. It would seem that kind of system must be fast enough to protect if it goes too far. I guess so far in the grainy photos of this event there doesn't seem to be a big enough gap viewable to set off a large effect on the FADEC. However as always I'm never sure about the pedigree of in-serevice older planes in their upgrade history. Of course I'm still wondering about the degree and timing of any loss of thrust in this event since they ran out of options on the last approach