The International Cessna^® 170 Association

I have found water inside both doors from time to time, and it found a seam to drain away slowly. This Annual I applied ACF50 through the airframe including inside the doors. Today I found some water in the RH door and it is not draining. I am considering a drain hole in the rear lowest part of the door. Has anyone done this before?

I was just considering the same question. I removed a door to strip some paint. After washing the door, I could not get any water to drain out. The problem is that if you drilled a hole it would drain inboard of the seal, unless you drilled through the outer skin, which I'm not about to do.

Drains are commonly 1/8” holes in fuselage bottom skins immediately forward of bulkheads. Sometimes they are faired with a “sea-plane fairing”. My 206 was tied down in my front yard before I had a hangar and one day I noticed it sitting tail-low after a heavy rainstorm.

Yep, the aft fuselage was holding tens of gallons of water…All the drains were blocked with debris. I spent the afternoon on my belly back there cleaning up and clearing those drains. (This was back before my present belly.)

It would be nice to know When or during What Event the doors became water-logged…but in any event if they often held water…I would want them to have a drain, even if it was inside the doorseal. It should be obvious that the rivet-line of the skin-to-the-door-shell is likely blocked by debris and/or paint. You might attempt to open the lower-aft area with a blade to provide a drain. (Note: The wing-root “shoulder fairings” (Items 9 and 10 “Wing Fillet Assy”) often hold water and should be provided a drain opening…usually a slight opening at the lower/aft seam line.)

Otherwise, a 1/8” hole in the outer skin at the lower/aft portion would not create either an eyesore or an airworthiness issue. (in fact, draining the door would improve airworthiness, IMO)

I noticed water inside the doors after washing. This time I taped over the door handles, but I think one door had water from an earlier wash. They used to drain through the seam, maybe the ACF50 plugged that path. I will send a vacuum tube down and try to extract it first. Taping when washing should stop the ingress.
Thank you.

One of my doors has a couple of random #30 holes drilled in the bottom section, the other is undrilled. I like Kevin’s idea of masking off the handle area prior to washing. If that doesn’t prove to be effective, how about adding a series of shims — maybe .032”? — along the bottom rivet line. Picture a dashed line of shim between the outer door skin and the inner frame. The spaced gaps between the shims would allow water to drain to the outside of the door seal. This would catch water that drips down the inside of the outer door skin, but the way the inner frame is stamped, it appears to allow water to pool along the inside edge of the door. Drilling a drain hole at the low point inside the door seal would be the only option here.

I left mine in the ramp a few days and some rain got in the baggage door. It had a small drain hole (inside the door, rounded bottom edge) that didn’t start draining until I opened the door…due to the seal. I plan to monitor this and treat the internal area.