People can’t walk five steps without hydrating themselves with some bottled water. We pay exorbitant prices for water thawed from glaciers or that has bubbled up from the deep. Or so it says on the label. Much of it is just plain tap water, which is – at least I hope – filtered and treated before bottling.
Every catering truck has flats and boxes of bottled water to be loaded on each flight. I remember when it was only the international airlines that carried Evian water and the like – and only then for their first-class passengers.
Water systems on aircraft were sort of an afterthought. But it seemed simple enough to put a tank in the overhead and run some lines down to feed the faucets. Simple enough – until it gets complicated.
First, we have to fill the tank and that means a fill line and fill valve somewhere on the outside. Easy, right? Then again, airplanes fly to places where travelers are warned to never drink the tap water. So those same travelers might also be skeptical of what is put into the tanks at these remote locations.
On that note, water carts and water trucks are sometimes neglected. There are procedures for disinfecting them that need to be followed.
So now we have to service the system and make sure the water remains free of contaminants. More complications.
One airplane model I worked on back in the 1950s that sported triple fins had its water tank located inside the sidewall of the aft baggage compartment. It was fitted with an electric pump to pressurize the tank – high-tech indeed. Lockheed had thoughtfully provided an access panel in the fuselage skin through which you could change the pump. Of course, the door was sized so the pump only fit through the hole at one precise angle, which took some time to discover.
What was more interesting was the algae growth I found when I pulled it out. It would have done an aquarium proud. I found no fish in the tank though. We disinfected the system, but the representative for the South American carrier who owned the aircraft thought we were just running up his bill.
Disinfecting and flushing this water system was no joy. It meant repeatedly filling a tow-around, 100-gallon cart. Since the cart was only fitted with a hand-operated diaphragm pump I spent a lot of effort pumping the water into the tank. Fortunately, it was only going into the belly tank, not up to the ceiling of the aircraft like some other models. Those took some real effort to service.
So if we’re going to be disinfecting and flushing, the tank better have a drain line, too. Besides, aircraft also spend a lot of time sitting around waiting – and airports tend to be among the coldest spots on earth. So draining was a must for overnighting in cold climates.
Our simple idea just became really complicated.
Not draining an aircraft in freezing weather where it cannot be kept heated overnight can have serious consequences. I was called over to LaGuardia to debrief a captain who had made an emergency return due to jammed flight controls. He also had difficulty in lowering his landing gear to boot.
He was rightfully irritated after I brought him out to the aircraft and showed him the cause. A water line under the mid-cabin floor froze during the night and split. There was no evidence of leakage because the line was frozen.
In the morning the APU was cranked and the cabin-heated air began to circulate under the floor. After takeoff, the line thawed and leaked. The water pooled on top of the pressure bulkhead that formed the top of the main gear wheel well. It then, under cabin pressurization, drained through the seals around control cables leading into the wheel well. The water quickly froze around the cables and aileron/spoiler mixer mechanisms and, for good measure, the landing gear control valve.