B767 300ER Avionics Bay

[fly777]

I am a SCCM working on the above a/c, during a recent flight, the forward toilet would not stop flushing. I followed the guidelines that we have as cabin crew and pulled the T bar under the toilet, this worked to start with, then the water started to pour continuously, there seemed no way to stop it, the flight crew were concerned as I was, that the water would enter the avionics bay. A PAN call was made and a diversion was planned. As the water was now pouring down the a/c and pax were now aware, I pulled the toilet shroud off and finding the shut off lever, stopped the water. The flight continued to its destination.
I respectfully ask if any engineer or pilot could tell me the consequences of a large amount of water getting into the avionics bay, I am aware there is a seal round the hatch, but this particular B767 is circa 1993. I would also ask if there is any kind of fire suppression system in the bay.
I want to make clear that I have the upmost respect for my flight crew and the airline I operate for, I merely want to put my mind at rest.

[single chime]

Just ask one of your pilots/engineers.

The internet is full of wakos so at times we do get paranoid.

[grounded27]

No fire suppression, the floor boards are supposed to be sealed, do not know how watertight the hatch is. The avionics racks usually have a cover. Bravo on your action (pulling the shroud).

I once launched a 742F that was loaded in heavy rain, one generator inoperative. About an hour into flight they lost 2 more generators (water contamination of the generator control units in the E&E) limping back home on only one. 99.9% of the time water entering the E&E will have no effect, it is quite common on freighters. None the less it should be addressed with serious caution every time.

[spannersatcx]

99.9% of the time water entering the E&E will have no effect, it is quite common on freighters

Sorry have to completely disagree with that statement. There was an incident either BA or QF can't remember, that nearly became a smoking hole because of water getting in the E & E bay, toilet or galley flooded and the drip tray was cracked. I'm sure if you did a search you'd find it on here somewhere.

We have strict guidelines when loading freighters in rain, L1 closed as much as possible, all freight double bagged, top layer removed at the main deck door to prevent any water getting in, buckets and/or mops to removed water from the top of freight if need be.

better to be late than never!

[TURIN]

That would be the 0.1% then. :)

To the OP,

There are recognised Spill Hazard Zones within some (all?) aircraft. This was incorporated in standard practices after a certain incident as described above caused multiple systems failures. I think it was a B737.
If there is a significant water spillage in this zone then an inspection of the electrical equipment compartments is required before the next flight.
The electronic/electrical racks are protected by sealed floor panels, drains around the door thresholds (on some anyway) and drip trays above the racks. so long as the integrity of these protections is maintained then any spillage should cause no adverse effects.
And therein lies the problem. Maintenance is expensive, lack of maintenance more so. :ok:

[Tech_Log]

There are recognised Spill Hazard Zones within some (all?) aircraft. This was incorporated in standard practices after a certain incident as described above caused multiple systems failures. I think it was a B737.
If there is a significant water spillage in this zone then an inspection of the electrical equipment compartments is required before the next flight.
The electronic/electrical racks are protected by sealed floor panels, drains around the door thresholds (on some anyway) and drip trays above the racks. so long as the integrity of these protections is maintained then any spillage should cause no adverse effects.
And therein lies the problem. Maintenance is expensive, lack of maintenance more so.Indeed I believe the SHZ isn't on all aircraft, never seen a Tech news briefing for the 747, I believe it's prominently aimed at the 737.
Indeed I thought (perhaps wrongly) that the SHZ was set up due to water leaking from gaps in the galley flooring. Requires a Tech log entry and inspection (If I remember correctly).


But to answer the question, I believe the risk of fire is greater from something within the E&E bay than from something external to it.

[RetiredBA/BY]

It was a Qantas 747 which had a lot of water in the E +E bay as a result of blocked galley sink, I believe. Cracked cover allowed water penetration. I think all the GCUs tripped, but they managed to get one gen. back on line, eventually.

They limped into BKK (IIRC) down to almost zero electrics.

Many years ago we had a quite a few incidents of spilled galley water in the VC10 getting onto the IRSs in the E and E bay and a waterproof cover was fitted over them.

Water and wiggly amps don't mix !

[DaveReidUK]

http://www.atsb.gov.au/media/3440510/ao2008003.pdf

[zerozero]

Can't imagine water in that compartment causing a fire, so fire suppression isn't really the concern. But I know of one case on a 747-200F where the Capt lost his IRS right at rotation, I assume as water sloshed around.

Then there was a 747-400F that lost a few electrical buses mostly related to pressurization and air conditioning controls.

Both situations resulted in diversions.

[t6 sparky]

Indeed I believe the SHZ isn't on all aircraft, never seen a Tech news briefing for the 747, I believe it's prominently aimed at the 737.
You obviously haven't been reading your tech news', naughty boy.
There are in fact SHZ's in the AMM temp revisions for both 747 and 777 and probably the Airbuses as well

[TURIN]

Yup. Airbus too, but not many know about it.

[Piper19]

If all drain holes work normally, some water should be no problem. Most computer shelves also have covers with drain tubes attached. E.g rain entering the cabin through the entry door or cargo door on freighters. However here also lies the problem: how many drain holes are full of debris or iced up after a longer flight...
A flood of water is always to be considered dangerous. I remember that we once had to shut down all elec power and take out every computer to let it dry, after the aircraft was flooded in a heavy rain storm with doors open. The aircraft had some flights after that with a lot of the computers needed to be replaced.