Originally Posted by TyroPicard
Both (known) TLA failure modes produce thrust Idle on the ground, and we have heard that 1.2 EPR was recorded on No.2 engine. Obviously some deep technical investigation required.
TP
These two failure modes are "Thrust Lever Disagree" and "Thrust Lever Fault".
Thrust above idle is set only if:
TL DISAGREE (different TLA readings from the two sensors):
- FLX or TOGA was set during takeoff: FLX or TOGA is retained until thrust reduction altitude
- MCT or below in flight with slats retracted: value of higher TLA sensor is used, thrust limited to MCT.
TL FAULT (no valid TLA reading):
- FLX or TOGA set durng takeoff: FLX or TOGA is retained until slat retraction, at slat retraction: MCT
- MCT or below in flight with slats retracted: MCT
In all other cases, the FADEC selects IDLE thrust!
Specifically:
-
always on the ground (except during take-off)
-
always with slats extended (except during take-off)
So we can pretty much rule out a thrust lever sensor failure of either kind here, especially since its ECAM message would have been accompanied by an aural signal, which is not on the CVR transcript.