PPRuNe Forums - A320 WTBs

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I was told an interesting little known fact about the Airbus. It seems odd and I have not seen it written anywhere so I do not know the validity of it. Maybe someone could shed some light on it.

Apparently, if you set the clock in flight to beyond 10 days, you cannot deploy during the approach the slats and flaps! Yep you read it right - this got my attention too. The logic seem to be related to the WTBs. The WTBs are supposedly tested at every landing and the test is supposedly valid for a period of 9 days. So if you were to set the date in flight to beyond 9 days, the computer (don't know which one) would interpret this as a need to test the WTBs and would activate them in the process prohibiting the pilots from deploying the slats and flaps during the approach.

Any truth to it ?

So.... you leave A320 parked for ten days or more, supposed WTB test is no longer valid and on the first flight the computer (you don't know which) decides to test WTBs. The supposed test is usually done during landing yet the computer (you don't know which) decides to test it at random time during flight, locks the WTBs in process and leaves aeroplane without flaps or slats.

Plausible?

Neither do I think so.

I've heard this story before but I can't find any reference to it in our A320 manuals - but that doesn't mean it's not an known issue! The relevant information could well be buried in a maintenance manual.

It seems unlikely that the system would lock the slats/flaps whilst airborne just because you went a few hours past the required maintenance interval.

What would happen 1 hour into the flight if you (legally) departed towards your home base 9 days and 23hrs after the last test?

I think it is probably a bit of an urban legend based on a misunderstanding of the following A330 issue:

From the A330 MEL:

Quote:

21-01 Electrical Clock
After any CMC failure, or electrical power interruption, resulting in loss of the UTC
indication (40 H 00, or amber crosses displayed on ECAM SD), initialize the UTC
indication, and the date using the MCDU.
Note: After initialization of the UTC indication on ECAM SD, if the following ECAM cautions are displayed on ECAM E/WD:
F/CTL FLAP TIP BRK FAULT
F/CTL SLAT TIP BRK FAULT
Flight crew should contact the maintenance staff to perform corresponding slats
and/or flaps WTB engagement test (Refer to the AMM) to clear cautions.

From the A330 FCOM 3:

Quote:

Note: The “SLAT (FLAP) TIP BRK FAULT” warning is triggered when the automatic test has not been performed during the last 10 days.
This warning being classified as a NO GO item in the MMEL it will have to be
corrected prior to the next flight. This can be done on ground by manually
launching the WTB engagement test accessing the CMS through the MCDU

Oddly, this is mentioned in our A330 manuals only and there is nothing at all about it in our A320 books.

Complete BS. :ugh:Let me enlighten you. It is applicable to A330/340 BUT NEVER in flight. You will get this ECAM WRNG in flight phase 1,2,9 and 10 only. Your " do not know which one " is called SFCC ! And if still interested, SIL 27-101-002 refers, myth busted. Now both back to your FSms

It was a question...chill.