Pitot static checks

[65MooneyPilot]

I tried to have my pitot static check done today and for the second time the airspeed indicator developed a catastrophic problem after they hooked up the tester. The airspeed now reads 40 MPH and does not move and the vertical speed indicator reads 1700 FPM assent. The needle still moves but it has lost its zero reference. The last time I had the test the shop(different shop) broke the airspeed indicator. The new testers have airspeed and static lines and is supposed to be all computer controlled. Something went wrong and of course they don’t know what happened. 
I was wondering if anyone else has had this problem? 

[carusoam]

Sounds like it experienced an overpressure problem like the last time…

It is not a normal behavior of instrument shops or instruments…

The usual amount of pressure required is often obtained by putting a hose on the pitot and rolling it up while watching the needles move… a few ccs of air goes a long way…

Lets see if Greg is around…   @Baker Avionics…

PP thoughts only, not an instrument tech…

Best regards,

-a-

[takair]

15 minutes ago, 65MooneyPilot said:

I tried to have my pitot static check done today and for the second time the airspeed indicator developed a catastrophic problem after they hooked up the tester. The airspeed now reads 40 MPH and does not move and the vertical speed indicator reads 1700 FPM assent. The needle still moves but it has lost its zero reference. The last time I had the test the shop(different shop) broke the airspeed indicator. The new testers have airspeed and static lines and is supposed to be all computer controlled. Something went wrong and of course they don’t know what happened. 
I was wondering if anyone else has had this problem? 

Almost surely user error, as Anthony suggested.  Very easy to do if somebody is not proficient.  In some ways, the modern, programmable systems, can be more apt to do damage if set up wrong.  

[EricJ]

+1 that it sounds like the tester broke your instruments.   It is fairly easy to damage the airspeed or the vsi if things aren't properly controlled.

 

 

Edited August 4, 2021 by EricJ

[65MooneyPilot]

I have a G5 installed but the FAA makes you keep the old steam gauges to be legal.
So my options are to fix the gauges and find someone who knows what they are doing. 
Or
Are there any certified airspeed stand alone gages that they can’t break. 
If I install a second G5 can I remove the Airspeed steam gauge for IFR flight?

[Mooney Dog]

2 minutes ago, 65MooneyPilot said:

I have a G5 installed but the FAA makes you keep the old steam gauges to be legal.
So my options are to fix the gauges and find someone who knows what they are doing. 
Or
Are there any certified airspeed stand alone gages that they can’t break. 
If I install a second G5 can I remove the Airspeed steam gauge for IFR flight?

My understanding is the G5 can only directly replace the DG or artificial horizon, not the actual airspeed or altimeter. If you're looking for that, the GI275 would be your next option in line. 

[65MooneyPilot]

Well the altimeter and the encoder worked perfect. If I could just get them to stop blowing up my airspeed indicators I will be in great shape. 

[takair]

14 minutes ago, 65MooneyPilot said:

Well the altimeter and the encoder worked perfect. If I could just get them to stop blowing up my airspeed indicators I will be in great shape. 

If shops did this routinely, they would go out of business.  Usually they would be liable for such damage and the margins on a cert. are tight to begin with.  Are you at a classic avionics shop who does carts routinely?  If they damaged your airspeed indicator, it is a good thing your G5 was not damaged as well.  Also, there is a risk of damaging their own equipment.  Sounds like you need a new airspeed and VSI. To replace those requires a simple leak check that many mechanics could do.  I would speak to the shop manager to understand what went wrong and what they will do to prevent it in the future,  if they don’t know the answer to that, I would not trust them to do it again.  
 

As a side note, there are also some hidden diaphragms that may have been damaged,  if you have an autopilot that is connected to pitot, that may now also be damaged.  As an example, even the old Brittain altitude hold was connected to pitot and had a very sensitive diaphragm that could be blown out.  These need to be disconnected prior to doing these checks.

[65MooneyPilot]

I don’t have an autopilot so no worries there and yes my G5 is still ok. We tested that separately after they realized something had gone wrong. Tomorrow I will be sending out the A/S and V/S to get them repaired. 
What leak check device can be used to check for leaks? Do you have a name and model number? Thanks

[N201MKTurbo]

That happens when the static system is opened when it is pumped up to altitude. You can do it by pulling the tube off, opening the alt static port, or opening one of the static drains. You will need your instruments repaired. They can almost always be fixed, but they need to be fixed.

[Guest]

6 hours ago, 65MooneyPilot said:

I don’t have an autopilot so no worries there and yes my G5 is still ok. We tested that separately after they realized something had gone wrong. Tomorrow I will be sending out the A/S and V/S to get them repaired. 
What leak check device can be used to check for leaks? Do you have a name and model number? Thanks

Isn’t the shop covering the damage they caused?  Unless the shop can show you that there was something wrong with your airplane which caused this, it’s operator error and they’re problem to fix.  
 

Does your plane have electric gear with an airspeed safety switch for the gear?  If so they should test it as well, just make sure its on jacks first.  You don’t want them retracting the gear accidentally, it’s happened before.

Clarence

[takair]

7 hours ago, 65MooneyPilot said:

I don’t have an autopilot so no worries there and yes my G5 is still ok. We tested that separately after they realized something had gone wrong. Tomorrow I will be sending out the A/S and V/S to get them repaired. 
What leak check device can be used to check for leaks? Do you have a name and model number? Thanks

Usually the same equipment is used for leak check, but it is less extreme.  Some shops have locally manufactured equipment for leak check, since it does not require calibration….  For example, for pitot leak check, one could use something as simple as surgical tubing rolled up to increase pressure….  However, even that, used incorrectly, could cause problems.  You don’t want folks learning these things on your equipment…

[EricJ]

12 hours ago, 65MooneyPilot said:

What leak check device can be used to check for leaks? Do you have a name and model number? Thanks

Leak checks are basic and can be done using the method of rolling up a hose connected to a pitot tube or just blowing in it for the pitot test.   The static test is a little trickier but can also be done easily.   It must be done carefully, though, as there are multiple ways in which the air instruments can be damaged, particularly the asi and vsi.

This vid covers the basics, and this guy just uses a syringe.   The only issue there is that you have to make sure the syringe isn't the leak source if you do find a leak.  On and airplane like a Mooney, often one static port is taped over and a hose in a lump of clay (or something that will allow a seal for the hose) on the other.   
 

 

[PT20J]

When doing the static certs, the pitot pressure has to be decreased along with the static pressure to keep the airspeed within the operating range or the overpressure damages the bellows in the indicator.

Here’s the procedure (with test limits) for testing for pitot leaks from the M20J manual, but it’s a generic test for any airplane.

 

[PT20J]

4 hours ago, EricJ said:

This vid covers the basics, and this guy just uses a syringe.   The only issue there is that you have to make sure the syringe isn't the leak source if you do find a leak.

Good advice. I wasted a lot of time trying to trace down a non-existent leak that was caused by the vinyl tube I fitted over the pitot not sealing well until I taped it. The Aero Instruments PH502 tube on my airplane also has a couple of extra holes. The one on the back I believe is a static port unused in the Mooney installation. It can be left open. But there is a drain hole on the bottom near the "bullet" that needs to be covered or it will cause a BIG pitot leak.

Skip

[takair]

3 minutes ago, PT20J said:

Good advice. I wasted a lot of time trying to trace down a non-existent leak that was caused by the vinyl tube I fitted over the pitot not sealing well until I taped it. The Aero Instruments PH502 tube on my airplane also has a couple of extra holes. The one on the back I believe is a static port unused in the Mooney installation. It can be left open. But there is a drain hole on the bottom near the "bullet" that needs to be covered or it will cause a BIG pitot leak.

Skip

Also, a Brittain dynertial has a calibrated leak in the pitot channel. That is one of the reason they recommend disconnecting them. So, those with Brittain should be aware of this. 

[0TreeLemur]

19 hours ago, 65MooneyPilot said:

Well the altimeter and the encoder worked perfect. If I could just get them to stop blowing up my airspeed indicators I will be in great shape. 

If the arcs on the C and E are the same, I have two spare ASI's  if you need a replacement. One came out of our '67 C, and I bought the other to keep on my desk at work from someone who did a panel upgrade.

Bottom of green: 70 mph

Bottom/Top of white: 63/100 mph

Bottom of yellow: 150 mph

Vne: 188 mph

The one out of our C worked fine, I replaced with one showing knots on the outer ring.  PM me if you want it.