PAP AOA leak test (G3X)

[LettersFromFlyoverCountry]

I sure must be missing something in the production acceptance procedures section g5-1.

This is for the Garmin g3x system. It says to disconnect the pitot tubing from the ADAHRS and move the AOA tubing to the pito slot. Easy.

Then it says using a 35cc syringe, push the plunger to 7.5cc and then it says to turn on the EFIS and use the syringe to slowly and carefully push air into the AOA port.

Are they talking that little rivet with the mandril driven out on the underside of the left wing? Seriously. With modeling clay? Modeling clay isn't an adhesive and lining up the vacuum tube with the mandrel hole is problematic. Shoot some air in the and, whoosh, bottle rocket tie.

They're talking about another port, right?

The other problem with the instruction is it says to push the syringe to 7.5cc, THEN turn on the EFIS, THEN slowly push more air until you hit 130 knots. Since I've already pushed it to 7.5, is 7.5 more liters enough to bring it to 130?

I'd like to get that far but the whole modeling clay things isn't working for me in this configuration.

Also, once I disconnect stuff on the ADAHRS, the screen on the G3X changes to show me G Force meter. Why?

Talk me through this.

 

[mburch]

Also, once I disconnect stuff on the ADAHRS, the screen on the G3X changes to show me G Force meter. Why?

Bob, it sounds like you have your G-meter set to "Auto Display" on the PFD Setup page. This will cause it to appear if the sensed G-forces exceed a certain threshold, or if the displayed attitude wanders into the "unusual" (which is probably what is happening in your case).

 

[N8DAV8R]

They are talking about the rivet on the wing. I had a pretty big blob of modeling clay involved in order to get a large surface area against the wing with some space for the tube coming off of the syringe. It looked like the end of a trumpet or tuba and was maybe 2 1/2" or 3" across.

I'm trying to remember that day in more detail. I may have had a helper watching the EFIS side while I held the clay/syringe contraption in place.

 

[LettersFromFlyoverCountry]

They are talking about the rivet on the wing. I had a pretty big blob of modeling clay involved in order to get a large surface area against the wing with some space for the tube coming off of the syringe. It looked like the end of a trumpet or tuba and was maybe 2 1/2" or 3" across.

I'm trying to remember that day in more detail. I may have had a helper watching the EFIS side while I held the clay/syringe contraption in place.

What size tube did you use off the syringe?

 

[rv12is]

It took me a few tries with the modeling clay, but I was able to get a really good seal. I did use tape to support the weight of the tube.

 

[N8DAV8R]

What size tube did you use off the syringe?

I wouldn't want to guess, especially having one strike today from screwing up the aluminum/stainless fuel fitting.

It needed to fit on the end of the syringe. I don't think I went and got anything special. Probably one of the tubings that was involved in the kit. Either the hard plastic or some of the stuff from the AOA kit?

 

[jsalley]

What size tube did you use off the syringe?

Bob - I think clear 1/8” PVC tubing is the right size to get a tight fit on a standard Luer-Lock syringe. It’s the same size that fits on the bleeder screw on the brake calipers. I got like 20’ of it for $5-6 at HoDePo.

 

[LettersFromFlyoverCountry]

I wouldn't want to guess, especially having one strike today from screwing up the aluminum/stainless fuel fitting.

It needed to fit on the end of the syringe. I don't think I went and got anything special. Probably one of the tubings that was involved in the kit. Either the hard plastic or some of the stuff from the AOA kit?

I first went with the size of the pitot abd AOA tube in the kit but getting that centered on that mandrel hole is just insane. The whole system is insane. There's gotta be a better way.

 

[N8DAV8R]

I first went with the size of the pitot abd AOA tube in the kit but getting that centered on that mandrel hole is just insane. The whole system is insane. There's gotta be a better way.

Consider not worrying about getting it centered and just having a big enough void to make sure you can't miss it. In the same way that a toilet plunger does not have to align perfectly with the exit.

Make a "bell" that captures the mandrel with some margin and a large area to contact the skin around it.

 

[LettersFromFlyoverCountry]

You know, I think I'm just going to disable the AOA and live without it. This is a crazy setup. This is a retrofit because there was no AOA in the early days of this wing kit and the design of it through the wing seems to guarantee leaks.

I got it to 130 but it started dropping before I even finishing pushing the plunger, then it bounced up again and then it cratered.

There's no real access to most fittings so finding a leak is problematic in the retrofit. It could be the test setup, it could be the syringe, it could be a fitting. It could be anything. Do I want to pull the wing off? I don't.

Man, it's amazing how much I'm starting to hate this airplane.

 

[N8DAV8R]

You know, I think I'm just going to disable the AOA and live without it. This is a crazy setup. This is a retrofit because there was no AOA in the early days of this wing kit and the design of it through the wing seems to guarantee leaks.

I got it to 130 but it started dropping before I even finishing pushing the plunger, then it bounced up again and then it cratered.

There's no real access to most fittings so finding a leak is problematic in the retrofit. It could be the test setup, it could be the syringe, it could be a fitting. It could be anything. Do I want to pull the wing off? I don't.

Man, it's amazing how much I'm starting to hate this airplane.

Did you do the step with the dow corning dielectric something or other on the fitting at the wing root? That could be an easy step to miss in the build sequence and might make a difference here.

You could proceed with the assumption that it's working fine and the syringe is the problem. You'll know at the calibration step whether it's something you need or want to mess with any further. I think it's a pretty foolproof air system with minimal connections so it's probably good. By the way, the same test is called out at each CI and every time the wings are pulled. Overkill.

 

[Walt]

I do static leak checks by taping over the port and sucking it down that way.

 

[rcarsey]

I've used the syringe and clay method.. it works. the pitot tube is very easy.. the syringe's tube fits onto the pitot tube snugly. I push in the prescribed amount of air, then use hemostats to clamp off my plastic tube to lock in the air pressure.. then I can let it sit for minutes and watch the airspeed. I think I lost 1 knot in 2 or 5 minutes.

The AOA and static ports are a little more difficult, and I've used a helper to sit on the wing and just watch the airspeed/altitude while I hold the modeling clay/tube/syringe in place for a couple minutes.

 

[Tony Kirk]

You know, I think I'm just going to disable the AOA and live without it. This is a crazy setup. This is a retrofit because there was no AOA in the early days of this wing kit and the design of it through the wing seems to guarantee leaks.

Okay guys, I designed an AOA Port Tester that will definitely work much better than the stupid modeling clay method.

You can read all the details and download my 3D model using this link https://makerworld.com/en/models/1738500-aoa-port-tester#profileId-1847272

It only takes about an hour to print on my Bambu P1S.

Bob, PM me your address and I'll mail you a fully assembled one! We want you to get your RV-12 flying before winter!

 

[jhrubos]

not having a printer, I would like to purchase such a device.???

 

[SARLDO]

Okay guys, I designed an AOA Port Tester that will definitely work much better than the stupid modeling clay method.

You can read all the details and download my 3D model using this link https://makerworld.com/en/models/1738500-aoa-port-tester#profileId-1847272

It only takes about an hour to print on my Bambu P1S.

Bob, PM me your address and I'll mail you a fully assembled one! We want you to get your RV-12 flying before winter!

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I would love to have one of these but don’t own a printer. Anyone willing to make and send? I’ll be very happy to reimburse for time, material, and shipping. Please let me know.

 

[jhrubos]

I would love to have one of these but don’t own a printer. Anyone willing to make and send? I’ll be very happy to reimburse for time, material, and shipping. Please let me know.

John Hrubos, 4567 Pin Oak Rd., Prospect, VA 23960

 

[jhrubos]

John Hrubos, 4567 Pin Oak Rd., Prospect, VA 23960

Okay guys, I designed an AOA Port Tester that will definitely work much better than the stupid modeling clay method.

You can read all the details and download my 3D model using this link https://makerworld.com/en/models/1738500-aoa-port-tester#profileId-1847272

It only takes about an hour to print on my Bambu P1S.

Bob, PM me your address and I'll mail you a fully assembled one! We want you to get your RV-12 flying before winter!

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I too could use such a device. John Hrubos 4567 Pin Oak Rd Prospect, VA 23960

 

[Brantel]

Tony, you da man!