Lonewolf_50
3hole, a few threads back, I think number 4, a gent who has taught in the A330 simulator related to us how some Unusual Attitude drills and recoveries required use of the trim wheel, manually, to get the pitch under control (in other than normal law, IIRC) in a suitable time frame. He wasn't sure if that was a "simism" or not.
Point?
There were or are some training drills that can be used to accustomize crews to using the trim wheel to control nose pitch in cases where the auto trim is either too slow or not helping redirect the elevators and THS where the pilot needs them. You could call the trim wheels a secondary flight control (Not sure if I am right about that) which means any rated pilot ought to know, like the flaps, when and how to use it.
And practice doing so.
Is it anywhere referenced to use it in this situation? I could only find the following references, where the mechanical trim is desscribed as standby system in case of autotrim not being availble.
THS MECHANICAL CONTROL
The mechanical pitch trim commmands are achieved by the handwheels in the
cockpit and transmitted to the input shaft of the THS actuator.
The THS mechanical control can be used :
- on ground, to trim the stabilizer when electrical control is not possible.
- in flight, as a standby system if automatic control (autotrim) is not available. (REF. LTTM)
The control wheels are used in case of major failure (Direct
Law or mechanical back-up) and have priority over any
other command. (REF: FCTM)
The purpose of the mechanical backup is to achieve all safety objectives in
MMEL dispatch condition: To manage a temporary and total electrical loss, the temporary loss of five fly-by-wire computers, the loss of both elevators, or the total loss of ailerons and spoilers.
It must be noted that it is very unlikely the mechanical backup will be used, due to the fly-by-wire architecture. For example, in case of electrical emergency configuration, or an all-engine flameout, alternate law remains available. In the unlikely event of such a failure, mechanical backup enables the PF to safely stabilize the aircraft, using the rudder and manual pitch trim, while reconfiguring the systems. (REF. FCTM)
When automatic pitch trim is no longer available, the PFD indicates this with an amber USE MAN PITCH TRIM" message below the FMA. (Ref. FCTM)
THS MECHANICAL CONTROL
General
The Trimmable Horizontal Stabilizer (THS) has a mechanical control system.
You can use the mechanical control system on the ground to trim the stabilizer when electrical control is not possible. The mechanical control system is also used in flight as a standby system if automatic control is not available.
The mechanical control transmits mechanical pitch-trim signals, put into the
hand wheels in the cockpit, to the input shaft of the THS actuator. (REF. LTTM)
We know now that it might have helped to defuse the situation, how could the AF447 crew know? By not knowing the above references?