All Things to All Men ... By Wire?

[747dieseldude]

The other day I was flying as an SLF on an A340-600.
We had a departure delay due to "a small problem in the toilet", which required a "computer reset" and in order to do that they had to remove all power from the airplane.
As a pilot of a not-so-sofisticated airplane, I wondered what lavatory problem could call for a computer reset?

[expatula]

Why didn't you check the maintenance/tech log entry to find out which problem was that?

Unless you are putting up a trivia here, for sure you would know the problem in the lavatory requiring such maintenance action before you accepted the plane for flight.

[screwdriver]

Just like giving your home PC a kick up the backside. Electrical transients can cause digital computers to behave abnormally. A brief power supply interruption can stop the problem. Problem was probably toilet "flush" ,lighting control, lav ventilation, or smoke det.

[wobble2plank]

It would have been a CID's (Cabin Interface Device ???? Can't remember) reset which during it's reset cycle switches all power off to the cabin to enable a full systems reset, test and recycle.

Doesn't take long, ground power to the flight deck is unaffected and generally seem to do the job.

Most likely it was a spurious smoke warning which generates a CID's Caution which has to be checked or extinguished (the caution that is) before flight.

[Gary Lager]

Had a similar thing the other day - spurous lav smoke detection. Alternative is go without serviceable lav.

No big deal, TIOAOA. Fly by Wire and associated dsign philosophy brings huge improvements in fuel efficiency and capability, the downside is occasional fault associated with a more sophisticated system. Every aircraft design is a tradeoff, hope you weren't delayed too long!

[FlapsOne]

expatula

He was SLF!!! Do your pax check the tech log?

Simple power off/computer reset for fire/smoke detection or flushing system.
Non-event really and better than going with an out of service dunny!

[White Knight]

Unlike the 332, there is no section for a quick toilet reset - done with a big blue button in the aft galley o'head CB panel.. Guess it's a full CID's reset which takes about 80 seconds on the ground, and according to the QRH there is a sequential cabin loudspeakers test and the cabin light may flash briefly.. From 345 QRH - imagine the 346 is similar:ok:

[john_tullamarine]

.. quite preferred the original thread title ... but changed to avoid the inevitable PC complaints ...

[tubby linton]

The quantity sensors sometimes become contaminated if a precharge has not taken place after tank emptying.This usually makes the system think the tank is full and all the associated toilets shut down.Thats how it worked on the 332.Sometimes large items would block the piping around the wing box area.The engineers would call these items "vampires tea bags"!!:eek::eek: