I recently noticed a bead of water hanging at the bottom of my rudder; closer inspection showed 2 drain holes which were blocked. After poking a bit of wire in both, I would estimate a cupful of water came out. The plane lives outside, and the water must have been there quite a long time; luckily the bottom of the rudder is fibreglass and not aluminium. Just something to be aware of on your next preflight.
Yes this is a big thing which few people know about.
The control locks need to be set up so the drain holes work right. A lot of people tie back the yoke with the car roof rack type elastic bands, all the way back, blocking the drain holes. More e.g. here and I have posted the massive Socata TB elevator corrosion pics before.
When my boss at the time had me doing some Lake Amphibian type training to new owners, he told me about the time he was ferrying a Lake to Canada from the US in the winter, it was a long, not so warm flight. He had neglected to remove the hull drain plugs. The bilge water, began to slush, then freeze at altitude. The result was frozen flight controls – literally, as they all run under the floor, through the bilge. He told me that he landed it on trim, flap selection, and power, with elevators which would no longer move. So, yeah, drain water!
Well done @Capitaine! YEs these should be checked regularly.
My airplane has about 10 of those in the lower fuselage, but two of them are in the pressurized area with a rubber diaphragm valve (supposed to close when under pressure). We ended up having to remove the valves (which are riveted in place) since they were fully clogged with years’ worth of debris and poking into them is a no no for fear of damaging the rubber valve. Made use of the occasion to replace the age-hardened rubber too.
So yes, poke but not in the pressurized part of the fuselage unless you really know what you are doing.
As I was complaining to myself about the above hassle of replacing the valves, and half-wondering if these drains were really necessary in a small airplane in the pressurized parts of the fuselage, a friend of mine landed and parked his pressurized E90 with one of the fuselage drains pissing water. There is no water system in this aircraft and the drain was in the pressurized area…go figure!
While I was on the phone with the maintenance shop the airplane had just come out of , my friend came out of the airplane with an empty bottle of mineral water and a happy face…Conveniently stored horizontally in a drawer inside a cabin locker, it had had the cap come off. It had fully drained 2l of water onto the underfloor…this had probably not been able to drain during the whole flight and upon depressurizing, it started to come out. The shop manager sounded very relieved upon knowing, since he was already starting to wonder which water system he had missed on this airplane…
These valves are also helpful for spotting fluid leaks from aircraft systems inside the pressure vessel, not just locker contents…
Either way you don’t want fluids unknowingly trapped in the fuselage or flight controls.
My elevators have holes in the trailing edge which are conveniently the low side of the controls when in locked position.
Antonio wrote:
As I was complaining to myself about the above hassle of replacing the valves, and half-wondering if these drains were really necessary in a small airplane in the pressurized parts of the fuselage
The PA46 does not have such clever technology, they simply put small normal holes in the pressurized part. I found this strange but probably the idea is that some cabin air has to flow out anyway so small holes do not hurt as long as it simply reduces a bit the air flowing out through the regular outflow valve.
Sebastian_G wrote:
The PA46 does not have such clever technology, they simply put small normal holes in the pressurized part.
That is interesting but if the pressurization system keeps up with that flow then nothing wrong with that. Cabin altitude will climb a bit quicker in case of pressurization source failure but surely you only have a handful rather than a dozen of those holes.
Piper must have been in the KISS gang or maybe an early proponent of Elon Musk’s motto about the best part
