Holy overheating toilet pumps Batman

[Decker]

Article here

[Nottingham Nick]

Link to the local Wilmington paper with photo.

Nick

Interesting as there are no toilet pumps on an A340!! Differential pressure is used in flight to suck the waste down to the toilet tank!!!!

Originally posted by Denzil
Interesting as there are no toilet pumps on an A340!! Differential pressure is used in flight to suck the waste down to the toilet tank!!!!

But it relies on vacuum - that requires a vacuum pump (generator) - an electric motor!

Yes, but what could possibly cause an overloading of said vacuum pump? I wonder if the majority of passengers on this flight were citizens of the United States? [}:)]

Regards
Bryan

Why???? The vacuum generator only operates at low altitude & is mounted outboard of the toilet tank which is mounted aft of the bulk cargo bay. Any overheating would only be felt through the aft galley floor!!!

Don't take my word for it, a quote from the A340-600 training notes ÒA differential pressure is necessary to move the waste to the tank. To produce this pressure a vacuum generator operates on the ground, and when the altitude is below 16,000 ft creating a diff press between 1 & 10 psi below cabin pressure. To do this the VSC checks the barometric altitude info from the ADIRU & energizes the motor start relay of the vac gen when necessaryÓ.

As a further precaution Òthe VSC monitors the thermal switch on the vac gen, if it becomes to hot the thermal switch opens & the VSC de-energizes the vac genÓ.

So an overheated toilet pump in one of the aircraft's restrooms created the heat felt in the planes floor?? I don't think so!!!

Originally posted by sixdownkeepsafedepth
Yes, but what could possibly cause an overloading of said vacuum pump? I wonder if the majority of passengers on this flight were citizens of the United States? [}:)]

Regards
Bryan

No - they were Brits - it was VGAS [}:)]

So does that make sense Bill, or are you sticking with your theory!!!

[Scrooge]

Bill, Denzil, depth breaths please.

Is it not possible for the trip on the motor to have malfunctioned causing the motor to over heat ?

I understand what you are saying (Denzil) and it makes sense to me, however I am also reading numerous reports from engineers on the ground that say that it was an overheating vacuum pump.

BTW..I do love these tech threads, just please, let's not make it into a personal fight, as any of us who have worked on some mechanical know strange things can cause stuff to happen and when it comes to something as complex as a modern airliner it can be the silly widget that goes out at the wrong time.

I would expect the C/B to trip if the VSC protection failed.

No battle with Bill, just further discussion to stuff he provided by PM which gives the impression that the vacuum generator is required to operate whenever toilet is flushed.

[Scrooge]

No issue with that, but lay off the ! marks please

Dave,
No problems with the !! from Denzil
Just having a friendly discussion with a mate!

Neither of us need deep breaths in that area!
I'll stick to the theory of a sticky relay or faulty sensor - vacuum motor never turned off when it reached 0.3bar differential - but we'll wait for that report....
[8D]

Actually while we joke about toilet pumps, it does hide a very serious issue - and why vacuum systems are much to be preferred to direct pumps as this incident shows. The CVR is interesting!

Hot floors, odd smells - crew took exactly the right action - and I'm sure Wilmington appreciated the visitation!
Interesting comparison how well VS dealt with the unexpected overnight compared with pax comments from another carrier that diverted there.

A question please Denzil? Which numpty wrote your manual? Forgive me for being old fashioned but surely figures quoted for a European manufactured aircraft should be quoted in metric and not the avoirdupois system! In any case any technical manual worth it's salt would describe the pressure as lb/f in2 and not psi!

Regards
Bryan

Bryan, the manual is a standard Airbus training document & does detail the px in psi & bar, i just omitted the bar for simplicity. This is a training document and NOT a maintenance manual.