Water Humidifiers:
All of the British-built aircraft that I ever flew had a water humidifier system. The DC-10 was the first machine that I ever remember that did not have such an animal. I started to have symptoms caused by dehydration that I did not fully understand. Fortunately, my GP was an ex-RAF medic and he put me right. Some exploration established that the cabin of a DC-10 flying from LGW to LAX could be as low as 7% humid (we normally like around 80 - 90%).
So, I stopped drinking lots of coffee and similar diuretics until I got to the bar after landing.
As usual, I have to tell a funny story. As Brakedwell will no doubt remember, the humidifier system on the Argosy consisted of a drip feed from the domestic (potable) water tank. The capacity of this tank is firmly imprinted upon my brain. It was a 26 gallon tank. At the bottom was a brass tap which was normally wire locked into the "drip feed" position.
The aircraft are coming brand new from the factory and I am a very junior sprog co-pilot. My captain is an "old hairy" called Dad Owen. We get airborne from Benson one morning headed for Malta. Just after take-off, the F/E puts the blowers on (air conditioning packs).
Suddenly, it is raining everywhere! It is coming out of all the punkah louvres and all around us. I look across the cockpit and Dad looks like a drowned rat and not a particularly happy person. I want to laugh but this is actually really serious.
My leader is far more experienced than I will probably ever be and the first thing in his mind is that all the invertors and other critical stuff are all underneath the freight floor.
So, what happened?
The airman who had been sent out to replenish the potable water system had just arrived on the station. Because the aircraft was brand new no one had got round to wire-locking the brass tap at the bottom of the domestic water tank to the humidifier position. So, when your man started pumping, he succeeded in getting 200 gallons into a 26 gallon tank.
The other 174 gallons had ended up in the pressurisation trunking and that is what we received when the F/E put the packs on.
The aircraft did not fly again for 6 weeks.