Blocked static port

[Bartman]

I did a VFR flight on my last leg today. Winds were strong out of the south and I was flying toward the Appalachian Mountains, so I knew it was going to be clear, but bumpy.  I was right.  I was by myself and on takeoff it was a gusty direct crosswind.  It was not fun, and I felt like I was not climbing at the usual rate.  Did a slow descent due to the bumps, but when I turned final the airspeed would not drop as expected when I raised the nose to add flaps.  As the airport got closer the ground was not moving by as fast as expected despite the ASI showing above the white arc.  A gust of wind made the stall horn chirp and I immediately dropped the nose and pulled the Alt Static.  The ASI dropped to the bottom of the white arc and my suspicions were confirmed, and it saved my bacon.  Suspecting blocked static and since she has been on the ramp a lot this summer I suspect water in the system.

The water drains on the wing root and below the battery access have never produced any results. Time for a static check next week.

 

[T. Peterson]

3 minutes ago, Bartman said:

I did a VFR flight on my last leg today. Winds were strong out of the south and I was flying toward the Appalachian Mountains, so I knew it was going to be clear, but bumpy.  I was right.  I was by myself and on takeoff it was a gusty direct crosswind.  It was not fun, and I felt like I was not climbing at the usual rate.  Did a slow descent due to the bumps, but when I turned final the airspeed would not drop as expected when I raised the nose to add flaps.  As the airport got closer the ground was not moving by as fast as expected despite the ASI showing above the white arc.  A gust of wind made the stall horn chirp and I immediately dropped the nose and pulled the Alt Static.  The ASI dropped to the bottom of the white arc and my suspicions were confirmed, and it saved my bacon.  Suspecting blocked static and since she has been on the ramp a lot this summer I suspect water in the system.

The water drains on the wing root and below the battery access have never produced any results. Time for a static check next week.

 

Nice immediate action! Grateful she didn’t stall on you. Well done.

[Slick Nick]

Seems strange that BOTH static ports could become blocked. Good on ya for pulling the alt static when you did. You can always tell when something “doesnt feel right”. 

[Ragsf15e]

You might pull the battery/avionics cover from the side of the fuselage and look down at the static tubing.  Should be able to tell if there’s water.

[N201MKTurbo]

Both static ports tee together. If water gets in, it can block the common line.

the static drain should be opened on preflight.

 

[N201MKTurbo]

Landing with blocked static instruments is very unnerving.

It is possible to land without them. It would be great to practice with an instructor or safety pilot, but I can’t think of how to block them and let the instructor still see them.

Fly your normal attitudes and power settings and you will be fine. Then go home and have a few cocktails…

[Hank]

7 hours ago, N201MKTurbo said:

Landing with blocked static instruments is very unnerving.

It is possible to land without them. It would be great to practice with an instructor or safety pilot, but I can’t think of how to block them and let the instructor still see them.

Early in instrument training, my CFII covered the pitot static instruments with paper angled for visibility from the right seat. Having owned my mooney for three years, and used it for frequent traveling, my CFII was surprised that I could fly requested speeds . . .

But I had a first tonight. Been tied down in off-and-on rain for several days, was thinking about the static drains while driving top the field, then forgot about them. On takeoff roll, ASI didn't move. I started to pull the throttle, then distinctly remembered putting the pitot cover on the hatrack and kept going as the ASI came alive but seemd low. The ASI, IVSI and altimeter were quite jumpy for the first 15-20 minutes; it's quite unnerving to see the ASI jump up or down 10 mph,  causing great swings also in the IVSI (usually several hundred feet per minute).

It wasn't until I was approaching to land an hour later that I remembered this:

Shoulda stopped and drained the static lines. Did it after landing, first time in 17 years' ownership that anything happened when I pressed the button, a few drops of water ran down my finger. Presed a few more times until a dry finger came away dry.

Ya'll be careful out there!

[Bartman]

8 hours ago, N201MKTurbo said:

Both static ports tee together. If water gets in, it can block the common line.

the static drain should be opened on preflight.

 

I can’t tell you how many times I have pushed the water drain valves at the wing root and under the battery access and have never gotten a single drop. Now that may be mostly because I'm in my hangar most of the time, but during summer and football season she is on the ramp a lot. 
 

I’ll go to the airport this weekend and remove the battery/avionics access and do the visual inspection on the static lines. As stated above the two drain valves still drain a common system, but the one under the battery should be the lowest in the system. 

[Fly Boomer]

8 minutes ago, Bartman said:

I can’t tell you how many times I have pushed the water drain valves at the wing root and under the battery access and have never gotten a single drop. Now that may be mostly because I'm in my hangar most of the time, but during summer and football season she is on the ramp a lot. 
 

I’ll go to the airport this weekend and remove the battery/avionics access and do the visual inspection on the static lines. As stated above the two drain valves still drain a common system, but the one under the battery should be the lowest in the system. 

I think the aft plunger drains static system; forward plunger drains pitot system.

[EricJ]

When I first bought my airplane it seemed evident to me that the airspeed indicator was off, as in reading too fast.   I only suspected this because of how it sounded and felt, and I was guessing it was reading about 10 kts fast, so I added 10 kts to all my approach speeds which worked pretty well.   When my avionics got refreshed we sent the ASI out for overhaul, and they said it was reading 15 kts fast, so I was still flying approaches 5 kts too slow.

That explained my no-float landings.   I'm glad I didn't trust the instrument.
 

 

[dzeleski]

I actually have a lot of issues with water getting in my static line. My airplane is in a hangar but I fly in weather fairly often. The lines are all ran correctly including the SB the adds the hoop up high.

I first notice problems with my AP, it will start to hunt ever so slightly in ALT mode, once that starts to happen I know I need to drain the static lines. But its fairly random on how or when it needs to be done. At this point me and my mechanic think it has something to do with hot and cold cycles forming condensation that eventually builds up.

What I do to drain the system is use a small jack and a piece of wood with a paper towel in between the wood and the button for the drain. I very gently jack until the button is pressed and I leave it like that for 20-30 minutes (do not get in the airplane when its like this, so you dont put extra pressure on the button). The paper towel seems to help wick the water out faster then without it and I dont need to sit there holding the button for ages.

[Ricky_231]

My K used to get water in the line after a big rain or an overnight freeze. I'd see the VSI and altimeter become "jumpy"; altitude would freeze then jump 200 ft after a few seconds. I never noticed anything on the ASI. Regardless, what I found would clear it up is I'd go up to anywhere between 5k and 8kft and do a couple of steep turns (45-55 degrees of bank). As soon as I rolled off the turns, the jumpiness would be gone and stay that way until the next rain or freeze.

I guess it's the equivalent of jumping up and down when you get water in your ears after swimming.

 

[Mark942]

Hi, I've owned my "E" for 6 years now and do almost all the maintenance TLC improvements myself with the help of a good AP/IA that looks over my shoulder. Having said that, I have an Alternate Static Air Valve under the panel installed by the avionics shop that did my panel upgrade. It is SO stiff that I can't turn it without a pair of pliers (another story about this horrible avionics shop in Fort Wayne), but I have never looked for the static drains.  Does anyone have photos of where these drains are so I can start checking these. Thanks in advance.

[AJ88V]

13 hours ago, N201MKTurbo said:

Both static ports tee together. If water gets in, it can block the common line.

the static drain should be opened on preflight.

 

I thought there were two lines connecting the static ports, one high loop that feeds the instruments and one low loop that connects to the drain.  At least I *think* that's how mine are configured.

FWIW, my static drain is 'crunchy' after sitting outside for two years.  Want to open up the empennage and have a peek.

[N201MKTurbo]

10 minutes ago, AJ88V said:

I thought there were two lines connecting the static ports, one high loop that feeds the instruments and one low loop that connects to the drain.  At least I *think* that's how mine are configured.

FWIW, my static drain is 'crunchy' after sitting outside for two years.  Want to open up the empennage and have a peek.

The two static ports are connected with a tube that runs along the top of the tail cone, it then runs down the left side of the tail cone to the static drain. From there it runs along the left side wall to the instrument panel.

[AJ88V]

38 minutes ago, Mark942 said:

Hi, I've owned my "E" for 6 years now and do almost all the maintenance TLC improvements myself with the help of a good AP/IA that looks over my shoulder. Having said that, I have an Alternate Static Air Valve under the panel installed by the avionics shop that did my panel upgrade. It is SO stiff that I can't turn it without a pair of pliers (another story about this horrible avionics shop in Fort Wayne), but I have never looked for the static drains.  Does anyone have photos of where these drains are so I can start checking these. Thanks in advance.

Wow!(???)  It's in your POH.  Static drain sticks out underneath the fuselage on the pilot's side below the rear access panel where your ELT and probably any old avionics are. (I think the battery may be there on the E-model too).  The pitot system drain is under the front edge of the pilot's wing near the wing root.

[EricJ]

53 minutes ago, AJ88V said:

I thought there were two lines connecting the static ports, one high loop that feeds the instruments and one low loop that connects to the drain.  At least I *think* that's how mine are configured.

FWIW, my static drain is 'crunchy' after sitting outside for two years.  Want to open up the empennage and have a peek.

You can see in this pic how the hard line from each static port goes over the top of the tail cone space and connects with the other static port, and then drops toward the drain at the back of the wing root.    That drain at the back of the wing root is the lowest spot when the airplane is on the ground, so should be where the moisture collects.    

[Andy95W]

40 minutes ago, AJ88V said:

Static drain sticks out underneath the fuselage on the pilot's side below the rear access panel where your ELT and probably any old avionics are. (I think the battery may be there on the E-model too).  The pitot system drain is under the front edge of the pilot's wing near the wing root.

Those were added in 1968, IIRC.  My 1967 did not have them, my current 1964 also never had them from the factory.  @Mark942 has a 1964 M20E, that won’t have these drains either.

[dzeleski]

43 minutes ago, EricJ said:

You can see in this pic how the hard line from each static port goes over the top of the tail cone space and connects with the other static port, and then drops toward the drain at the back of the wing root.    That drain at the back of the wing root is the lowest spot when the airplane is on the ground, so should be where the moisture collects.    

 

SIM20-43 (https://mooney.com/wp-content/uploads/2020/12/SIM20-43.pdf) was not followed for that install just as an FYI. The T should be higher up, that should help prevent water going down the actual static line and collecting in the belly.

Edited 16 hours ago by dzeleski

[EricJ]

3 minutes ago, dzeleski said:

SIM20-43 (https://mooney.com/wp-content/uploads/2020/12/SIM20-43.pdf) was not followed for that install just as an FYI. The T should be higher up, that should help prevent water going down the actual static line and collecting in the belly.

Yeah, mine's still in the original factory config.   That's a good diagram to show how the static tube drops down to the drain location, though.

[Mark942]

Thanks @Andy95W I think I will ask my AP/IA if I can install this drain this winter as a nice little Hanger project.  Always thought it odd that I couldn't find a way to drain the line. Thanks for the clarification. -mark

[PT20J]

The drain valve is a Mooney custom part. It comprises a machined body that is riveted to the skin and threaded to accept a fitting to connect the static line. The actual valve is a clevis pin with an o-ring and a coil spring. I wonder what this mash up costs from Mooney? Maybe a used one from a salvage yard?

[MikeOH]

5 minutes ago, PT20J said:

The drain valve is a Mooney custom part. It comprises a machined body that is riveted to the skin and threaded to accept a fitting to connect the static line. The actual valve is a clevis pin with an o-ring and a coil spring. I wonder what this mash up costs from Mooney? Maybe a used one from a salvage yard?

WOW!

You'd think they could have found some suitable 'catalog item' rather than 'rolling their own'!