dlramp4life From United States of America, joined Jun 2011, 867 posts, RR: 1 Posted (10 months 3 weeks 6 days 15 hours ago) and read 2017 times:
Since the weather has gotton below freezing every night for the past week where I live, we have been instructed to drain water tanks on all aircraft that won't be sitting at a gate connected to power all night...
My question is if there is power from a GPU going into the aircraft, how the plane having power does prevent the water from freezing over in potable water tank?
bartonsayswhat From Canada, joined Oct 2007, 434 posts, RR: 0 Reply 1, posted (10 months 3 weeks 6 days 12 hours ago) and read 1981 times:
Water tanks are heated. Our ground manual (CRJ200) tells us to to ensure RON aircraft are plugged in overnight, ground service switch is on, and that the water system power switches in the galley are on. This ensures the heater ribbons are turned on. SOP is to take a diesel GPU out to the plane and keep the heaters on rather than drain the system, as not all of the water from the lines will come out and cracking in the lines could occur.
I see you live in Canada. Maybe your water tanks are heated. It is not normal.
Standard aircraft have no heating at all for the water system. Water line heating with electric ribbon heaters is an option that is only taken up by airliners in arctic regions. The rest of us drain the tanks.
I find that with an A320, putting a cabin heater on will keep the water flowing down to around Minus 20 degC overnight. Putting on ground power has no effect at all.
The rules here are, down to M5degC do nothing.
M5 down to M15 put on cabin heater
M15 down, drain water system.
Exactly; the ribbons heat the lines, not the tank. I'm not aware of any aircraft that has optional tank heat.
Quoting bartonsayswhat (Reply 1): as not all of the water from the lines will come out and cracking in the lines could occur.
Not if it's designed properly. When rampers drain the potable tank, they're not getting the water out of the system, sure. But when we mechanics do it, we know to open the OTHER drain valve, which lets the remainder of the water gravity feed out of the system's lowest point.
Quoting Tristarsteve (Reply 2): I see you live in Canada. Maybe your water tanks are heated. It is not normal.
I doubt it; here in Alaska, the 737 tanks aren't heated... just the lines.
After learning the hard way that forward lavatory lines are VERY HARD TO THAW, we leave heat on the planes, and drain the water anyway! If someone (ramp) leaves L1 cocked while they are servicing the cabin, the door hinge covers aren't sealed shut, and blow icy air straight into the forward lav cavity that houses the water line! Took us ages to figure that one out.
All of this is why I eagerly await the arrival of May, when temps no longer warrant potable water worries!
bartonsayswhat From Canada, joined Oct 2007, 434 posts, RR: 0 Reply 7, posted (10 months 3 weeks 4 days 12 hours ago) and read 1509 times:
Quoting AA737-823 (Reply 4): The water lines are optionally heated; the tank is not.
Just look at the winter ops chapter in our ASM, and it only mentions to make sure the ribbons are just turned on, I guess I always just imagined them in the tank. It says water MUST be serviced full, as the lines on the CRJ don't completely drain. Also service lavs full with Type 1 glycol 100% and a cup of undiluted deodorant liquid, or 50-50 automotive anti freeze.
If it gets below -25 and the A/C RONs outside, then the covers go on, and a heater unit must be attached. If heater is unavailable, then the APU is run and the plane is babysat..