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-   Tech Log (https://www.pprune.org/tech-log-15/)
-   -   A320 All ADRs Are Wrong during unreliable speed (https://www.pprune.org/tech-log/593238-a320-all-adrs-wrong-during-unreliable-speed.html)

Uplinker 24th Apr 2017 22:47
When switching off two ADRs, you might want to leave PF's side one on.

FlightDetent 25th Apr 2017 05:29
1 Attachment(s)
Attachment 2142

Back to BEFORE post one before anybody finds out about this little chat of ours?

vilas 25th Apr 2017 16:43
Normally it blends inputs from rudder pedals and the two dedicated tillers to command nose-wheel deflections. The ratio is dependent on airspeed.

If ADR 3 might have an unreliability the system hasn't detected (which I think is what we're assuming), and you left it on, it seems like you could still end up with something like a large NWS deflection early in a cross-wind landing (because the ADR thought the airspeed was low when it wasn't).
This is not factual because it is ground speed and not airspeed.
DSC-32-20-10 P 1/4
The BSCU transforms these orders into nose wheel steering angle. That angle has the following limits, which depend on ground speed and the origin of the orders.

vilas 25th Apr 2017 17:07
Uplinker
When switching off two ADRs, you might want to leave PF's side one on.
Why would anyone do that? Because PF habitually will believe in the wrong speed displayed and could get in trouble.

vilas 25th Apr 2017 17:34
topla abicim
During Un.Speed ADR Cx Proc you aware that your all adr are wrong
You have to turn 2 of them off (IF THERE IS NO BUSS)
My question is which one should remain?
As I know,
If you keep ADR1 you can maintain XPDR/ATC1 and GPWS
If you keep ADR2 you can maintain XPDR2 and NW/STR
If you keep ADR3 you can use you LDG GEAR otherwise GRAVITY
The whole discussion has gone on the wrong track. Your first condition was all ADRs are wrong. So you keep one only for stall warning. After that you are treating that one as good one. No this one is also bad so the three options you mention are really not available. You will land not as dual ADR fail procedure but triple ADR fail. So the gear is lowered by gravity anyway. GPWS if available with faulty ADR1 you will use it only to your peril. And triple ADR fail procedure doesn't say NW steering as inop. You will have to depressurise the aircraft manually because faulty ADR is not going to do it.

45989 25th Apr 2017 18:28
Try thinking outside the box. GPS ground speed is available on pretty much all hulls after MSN 800ish.
Would have saved AF 447 if it was used or recognised
Fly the plane. Keep the nerdy stuff on the ground!

Uplinker 29th Apr 2017 06:25
Originally Posted by vilas (Post 9752046)
Uplinker
Why would anyone do that? Because PF habitually will believe in the wrong speed displayed and could get in trouble.
During my "AF447" SIM experience (I was in RHS), when the nose dipped, I suspected the V Alpha Prot issue, so I applied the OEB procedure and switched off ADR 3 and 2. The TRE then leaned forwards and put ADR 2 back on and switched off ADR 1.

But of course, he knew which ADR's he had 'failed'. I didn't.

punkalouver 16th Jul 2019 14:29
Originally Posted by vilas (Post 9752078)

And triple ADR fail procedure doesn't say NW steering as inop.
I think that is correct. I am looking in my ,manuals and see nothing mentioned about lack of nosewheel steering.


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