Pitot Drain pre-flight check

MTjb82

Sorry if this a dumb question but I can't find the answer in my POH and even my CFI didn't have an answer. I have a 1976 PA-28-151. I bought the plane to use as my trainer and am in the process of getting my license. On the pre-flight checklist that came with the plane, under the in cockpit section it has "check pitot static drain". After some searching, I found the drain just aft of the fuel selector. But what am I supposed to be checking?

Thanks!

Scott Sherer

Hi, this isn't a dumb questionat all! If you're plane is left out in the rain or it's hot and steamy out one summer day you can get rain water or condensation in the pitot and static systems rendering them inop. This can happen when you're washing the plane, too. When you're preflighting you push both buttons and if there's any water in the static or pitot system it will drain out at the lowest point in the system directly under the buttons. Just push it for a couple of seconds and your're done. There are two buttons, right? One for static, one for pitot.

MTjb82

Thanks Scott. Yes there are two buttons and since I found them, I've been pushing them during my pre-flight.... just didn't know why. ha ha. Luckily the plane is parked in a hangar and we definitely don't have much humidity in Montana this time of year.

Scott Sherer

Same here in wisconsin Happy holidays!

arrow76r

Buttons??? On my Arrow??? I have never seen any such things. Where might they be, Scott??

Scott Sherer

Hi Jim,
They are logically, if not poorly placed on the left side about 18 inches behind the fuel selector valve, left of the pilots seat near the floor. You have to slide the seat backwards to get to them. PA-28, 32, 44 and 34 are all them same. Some of the early PA-28's don't have them but they're really needed to keep water out of the pitot static system.

arrow76r

Scott,
Nothing there unless they are hidden behind the wall covering. There is no mention in the POH "pre-flight inspection" description either.

arrow76r

Addendum...even though I have flown in some pretty heavy rain I have had no indication of water in either the pitot or static ports (on the same "mast" , of course). I did add an alternate static source many years ago because the plane did not have one originally.

Scott Sherer

Ok, sounds like your model doesn't have the drains. I spoke a few months ago with a member who added them because he was having problems.... I'm glad you're okay

arrow76r

Scott,

Attached is a photo I just took of a page from my parts manual that shows there is no pitot-static drain for my s/n Arrow (SN 35316).

Scott Sherer

Hi Jim,
Here's a scan of the parts manual for my Arrow including the parts list.

arrow76r

I see your Arrow has separate static ports (2) at the rear of the fuselage. My static port and ram air are located on the same "mast". The configuration on your drawing is quite complex and definitely not going to be incorporated in my bird!! I figure after almost 50 years it is what it is! As I mentioned above, I have not had any issues with water in the system but there must have been some reason Piper made the change. Thanks for the data!! FYI, my Arrow also had the automatic landing gear extension system which was, fortunately, removed long before I bought the plane. I have heard only bad vibes about that system.

Scott Sherer

Ok, thanks for the update, Jim. My Arrow has the same auto-extension system but it's been disabled and placarded.

davewhite99

I know this is an old thread, but does anyone know what o-rings these drains use? I assume you can unscrew the entire valve to replace the o-rings. I would like to replace them just as a precaution.

planewrench

Dave, suggestion,, I would not screw with them UNLESS you are having a issue . These are NOT owner maintenance items and IF you do manage to take them apart, ( dont know of any one that has) you will need at MIN a leak check performed to verify integrity. YOu might need a full IFR check again. Knowing where they are is important, but these are one of the few things better left alone. There is no way to verify any repair to these short of a pitot static check. CArl