AT and FD behaviour with the FD switches OFF

[Britjet]

Pushing TOGA above 80kts on take-off  - I tested this last week and it didn't bring up the FD.

HOLD engaging THR REF with landing flap? That would be entertaining! - but I can't see why it would happen, I will try it out - but I'm not scheduled in sim until later this month..
Peter

[osss]

Pushing TOGA above 80kts on take-off  - I tested this last week and it didn't bring up the FD.

I did not try. That is what FCOM states about

HOLD engaging THR REF with landing flap? That would be entertaining! - but I can't see why it would happen, I will try it out - but I'm not scheduled in sim until later this month..
Peter

I don't know either why A/T becomes alive

Stan

[Britjet]

Pushing TOGA above 80kts on take-off  - I tested this last week and it didn't bring up the FD.

I tested this again in the BA sim yesterday. If I recall in the FCOM it does say somewhere that they should appear, but it was not the case. They do not.

Peter

[Hardy Heinlin]

Hi,

so in the BA sim the flaps-out-of-up condition to enable the TOGA switches refers to the flap lever position only. Not to the actual flap surface positions.

As this has been tested on the ground only, can anybody confirm that this also applies in flight?

In the existing PSX versions, the TOGA switches are enabled when the actual flaps are out (or when G/S is captured, as usual). This means that in case of an alternate flap extension with the lever in UP position, the TOGA switches remain enabled even when a G/S is unavailable. This sounds like an advantage. On the other hand, if the flap lever was the reference, TOGA would be enabled even when the actual flaps were stuck in the up position for a flaps-up emergency landing with the lever out of up. That might be an advantage as well.


Regards,

|-|ardy

[John H Watson]

I recall seeing low airspeed value logic for certain systems on other Boeing aircraft (where the event did specify the aircraft had to be in the air). This 80kt logic doesn't necessary mean that it happens on the ground. It may just mean that the lower airspeed limit allows the function to operate even if the aircraft is stalling.

e.g. the ram air turbine (for backup flight control hydraulics) on a 767 will deploy if:

The aircraft is in the air AND
airspeed is above 80kts AND
both engine N2 speeds are below 50%

Having two sources of flap position in the air and on the ground sounds like too much effort (for Boeing, I mean)

Cheers
JHW

[John H Watson]

Hi,

so in the BA sim the flaps-out-of-up condition to enable the TOGA switches refers to the flap lever position only. Not to the actual flap surface positions.

How did you deduce this, Hardy? The wiring schematics only show actual (inboard TE) flap position going to the FCCs.

[Hardy Heinlin]

Peter? :-)

Well ...

Which source is correct? The BA sim or the wiring schematics?

I don't know.

Either one can be wrong.


Apropos ...

1.3.014. Modification 10.1.1-beta21 undone: GA thrust limit is again locked by landing flaps as well.

That item was different in a previous BA sim ride as well, where GA was not locked by landing flaps. Now in the latest BA sim ride it was locked; that's why I removed that previous modification.

Could it be that this wasn't due to finger trouble but because these were two different BA sims?

Is this a mix of Thales sims and CAE sims?


|-|ardy

[John H Watson]

This is getting confusing...

I tested this again in the BA sim yesterday. If I recall in the FCOM it does say somewhere that they should appear, but it was not the case. They do not.

so in the BA sim the flaps-out-of-up condition to enable the TOGA switches refers to the flap lever position only. Not to the actual flap surface positions.

Regarding automatic FD operation at 80kts (airspeed) on the ground ... How did we arrive at flap position and not flap lever position.

Peter? :-)

I must have missed a message.  How did Peter show you that the GA system is looking at Flap Lever position?

[Hardy Heinlin]

That info reached me by email :-)

[Britjet]

Regarding the landing flap position not locking the GA mode. That was probably poor observation on my part. A re-check on another day showed that it did lock the indication at GA.
The appearance or otherwise of the FDs in GA mode above 80 kts was with the flaps set normally for take-off - so this was a speed-related issue - nothing to do with the flap lever position.
Regarding the FD GA mode depending on flap position (at 0 kts). In the sim it was positively shown to be the flap lever position, not the indication. Three of us checked it and I believe we have it on video.

Peter

[John H Watson]

Regarding the FD GA mode depending on flap position (at 0 kts). In the sim it was positively shown to be the flap lever position, not the indication. Three of us checked it and I believe we have it on video.

FD GA mode on the ground? Sorry, I don't understand what stage of flight is being described.

[Britjet]

It wasn't a stage of flight as such. The question that was asked on a thread some time ago was what would cause the thrust levers to engage on the ground - e.g. while taxiing or even the gate.
The sim answer was that it was a function of flap lever position away from UP.

[John H Watson]

Thanks, Peter.  So the TOGA switches were pushed before the TE flaps started moving? Or did you extend the flaps in Alternate Mode to bypass the flap lever and nothing happened?

Although my books specifically say that flap position RVDT data is used by the FCCs*, I did find a possible signal path in the wiring schematics.  There is a label called "Flap Motion Required" in the Flap Control Units going into some FCU signal processors.  This might be a Flap Lever RVDT data and this might be sent to the FCCs.

I understand that thrust is handled by the FMCs, but there is no direct input from the FCUs to the FMC. My books say that the FMCs get flap position from the Mode Control Panel (I assume the FCCs send flap data to the MCPs).

Cheers
JHW

[Britjet]

It was a case of pushing TOGA before the flaps reached 1, but with the lever at 1.
I guess it could be a "flaps out of up" signal. The only way to prove that would be to inhibit the LE flaps by CB action etc before moving the lever, but we didn't do that.
Peter.

[Hardy Heinlin]

Hi Peter,

I thought you tried it the other way around: The actual flaps were out of up and in transit while the lever was UP.

This way it's clear that the lever is up and the flaps are out.

In reversed order, as soon as the lever is out of UP, the flaps may instantly be in transit and just the EICAS indication may lag behind a little bit.


|-|ardy

[John H Watson]

There's a huge delay in "GA" annunciation in the KLM Breakoff Landing video. It almost coincides with the flaps actually reaching flaps 1.

https://www.youtube.com/watch?v=GRtWNZwgGn8&feature=youtu.be

Around 9 seconds from the sound of the lever going into the slot at 3:55

[Hardy Heinlin]

So, not correctly modeled in the BA sim?

Edit: This has nothing to do with the discussion above which is about enabling the TOGA switches, not about setting the G/A thrust limit mode. The G/A thrust limit mode in PSX is already set by flap extension, not by flap lever.


|-|ardy

[Hardy Heinlin]

I think, in order to ignore electrical noise, the "flaps-out" signal from the flap position RVDTs appears when the flaps are a little further extended, not already at +0.00001. I.e. somewhere between UP and 1.

And I think this is also the flap-out signal that goes into the ignition system logic. To avoid flutter near the UP position.


|-|ardy

[John H Watson]

Edit: This has nothing to do with the discussion above which is about enabling the TOGA switches, not about setting the G/A thrust limit mode. The G/A thrust limit mode in PSX is already set by flap extension, not by flap lever.

Ah, ok.. I thought it might be related (?)

[Hardy Heinlin]

There's a huge delay in "GA" annunciation in the KLM Breakoff Landing video. It almost coincides with the flaps actually reaching flaps 1.

https://www.youtube.com/watch?v=GRtWNZwgGn8&feature=youtu.be

Around 9 seconds from the sound of the lever going into the slot at 3:55

This little additional delay is now implemented in PSX 10.1.6:

http://aerowinx.com/board/index.php?topic=4191.0

(Item 1.6.006.)


Regards,

|-|ardy