Fuel Tank: Water Draining sometimes "difficult"

[jettison valve]

Good afternoon all,

Every once in a while, we´ve been running into trouble when water draining from the fuel tanks is due. With shorter groundtimes it´s becoming more and more difficult to perform these tasks, especially in cold ambient temperatures / winter season. Frozen drain valves, too low tank temperatures for ice in the tank to melt, too little time for the water to settle around the drain valves - these are the major concerns. :sad:

How do you deal with this issue? I would be very interested in A330 ETOPS operators´ feedback as the CMP requires the wing tanks to be drained every 7 days.
Do you use hot air blowers? Do you refuel several tons to "heat up" the tank? Or have you escalated this 7d task so that it falls into a hangar downtime with a long groundtime? :confused:

Regards,
J.V.

[mitzy69]

Read the Check sheets it might say if the transit is less than an hour that a fuel water check is not required. Or needs 20 minutes for water to settle out of a refueled tank.
Modern aircraft have pipes that draw fuel from the lowest part of the tank by jet pumps and place the fluid near the inlet of the main booster pumps, so water does not build up past a few drops.
The daily check at main base might require a fuel tank water check to be completed, but then if a drain valve does stick open due to ice there is time to fix it.

[FMU]

JV, at Qantas we call out fuel drains on our A330s at each "7 day" check. We find the same problems you have encountered- fuel temp too low, water still "frozen", frozen drain valves. We recommend to carry out the drain as long as possible after arrival, (at least 5 hours) but failing that we sometimes refuel with "warmer" fuel and then do the water drains.
I also find that too much water in the tank can lead to fluctuating/degraded fuel qty indications. I don't think escalating the water drain past the 7 days would be appropriate.

[Terraplaneblues]

We had a jurrasic 737 with fuel indication over read, which is a symptom of water in the fuel and iced lower wing skins & limited downtime. Cycling the flaps/slats & spoilers & flying controls with the engines running & elec pumps on dumps heat into the fuel through the heat exchangers, and was enough to warm up the fuel and melt the ice & enable a good water drain, I am sure the temp was positive though.
Have operated in Scandinavia with temps 15 below or more for months and the only way we could do it was to wait for a hangar input.

Boeing Maint Planning Data section 6 systems includes wording not unlike this:
Fuel tank sumping task intervals should be determined by operators and based upon their operating environment, fuel management resources and in-service experience.
Would be worth checking the Airbus document.

[spannersatcx]

Ours is ground time >3hrs and fuel temp 5C or more, and BEFORE refuelling. No point in doing it after as stated here.

[A345]

Hi all,
as per our company regulations, water drains are part of the DAILY CHK. fleet wide. when the A/C is on ground for atleast 3 1/2 hrs. At outstations where temperatures are low, we have the option of deferring it till the A/c gets to Base by making a tech log entry for the task...malfunctions in probe indications is a very chronic problem on ALL Airbus A/c due to water contamination..

[Beaver man]

Not quite in line with the topic but... never, NEVER carry out a water drain check by yourself! Early one winters morning, 0 bloody hell o'clock, on a remote stand, dutifully carrying out the task only to have the drain to stick open!! There was BM, stuck on top of the ladder, thumb in hole, a la little dutch boy, do I run to the nearest phone, about 100 yards, or stay there hoping someone will pass? Luckily a colleague came by after a few minutes to assist. Only after the obligatory call to get eveyone else out to have a laugh and take the necessary photos!!

[Long Bay Mauler]

I am sure you could refuel just so as to warm up the fuel,wait an hour or three,and then do the drains.But as spanners says,no point in refuelling prior to a service and then doing the drains.

I regularly pull 3 litres or more from the inboard tanks each day,so it shows how important to do them religously.This also depends on where the aircraft operate and what the ground tanks are like in foreign ports.

[LandASAP]

Hello,

in my company the water draining from the fuel is a weekly item. Normaly it's planned in a nightstop or long ground times. When a weekly has to be done we refuel 15tons warm fuel or puting heaters under the drain ports.

Greetings

[jettison valve]

First of all, thanks for your answers! :D

mitzy69:
What you describe is valid for the Boeings, not for the Airbusses I have worked on so far. Airbus UK state that they would have certification problems in Europe with a Boeing system (i. e. inject the scavenged fluid next to the boost pumps). In detail, the A330/A340 classic system sucks fluid from almost the deepest point (avoids freezing) and delivers it back to the tank (Airbus calls this a "water mixing" system" in order to "keep the water in suspension").
B747s/B777s have the superior system that you describe. Very effective, apparently.

FMU:
Supposing that you operate the A330 on ETOPS routes (and you need to comply with the CMP per CASA order), you havn´t drained the tanks in the last seven days, and you have a short ground time today - do you defer the draining (in my point of view not possible) or do you run into a delay or... :O:mad::\?

Terraplaneblues:
The MRBR / MPD are ok, just as you say ("operators experience"). On the A340 classic, we´ve started escalating the task interval for wings, and for the trim we have had good experience with 2A. The whole madness starts with the CMP for ETOPS operations. :ugh:

spannersatcx:
Contrary to you, we have a cold home base. In order to meet authority requirements and to give a least a little sense to the drain excercise, you need to have a warm tank / wing. In winter over here, you can achieve that by grounding the a/c in a warm hangar for several hours :mad:, or refuel with comparatively warm fuel (and then wait again for the stuff to settle down). Option 2 is not the optimum but better than option 1. Agree?

A345:
Technically a perfect solution, but manhours intensive and therefore expensive. And you could overrun the 7d CMP requirement for the twins, if you don´t take perfect care of the drain accomplishments individually.
In my experience, FQIS problems on the A345/A346 usually came from an initially stupid then over-engineered (Parker) software, harness issues, failed terminal lugs, and only to a small extent due to water (had a few weeks long nightmare with a production fault at Airbus in that respect, I must admit though).

Beaver man:
Got showered and still smell...? :}

LandASAP:
That´s our compromise as well. Plan a several hours downtime for the A330 weekly (:ugh:), refuel to the minimum fuel in our network, wait, wait, wait - drain, and sign off.

Thanks again for your advice!
J.V.

[spannersatcx]

I can assure you it gets cold where I am. Have had a drain stick open due to cold before.

We have (or used to I'd have to check) the option to defer it to main base, not sure we do on the airbuses anymore, will check. Adding warm fuel is ok provided you have sufficient time to allow it to settle, unfortunately on the line (where me is) we don't have that luxury.

So the answer is many and varied and depends on your airline and how good your planners are at getting it on the ground somewhere warm if it's due a weekly!