TPMS on RV-12s

[Brett H]

I realize that TPMS has been previously discussed. But, as with anything electronic, time brings change. Namely, smaller size and increased capability.

That has been folk’s experience?

What would you recommend and why?

Is the sensor small enough to clear the nose wheel fork? If it’s only possible to install TPMS on the main wheels, is it still worth while?

Thanks.

Brett
Columbus, IN N4BH

 

[12vaitor]

My experience with a TPMS on the mains (sensor is too big for nose wheel clearance) is it was novel to begin with, but not much use if you know/assume the leakage rate and just accept adding air every 4 or 5 months. I have wheel pants installed and at some point you get used to what the tire sidewall should look like (and they should both look the same on preflight). I have had one flat and that was because the o-ring in the TPMS sensor was damaged and the air leaked out after I added air to the tire. The other problem is the display battery does not last long and the solar cell charger does not work in a dark hangar, so one more thing to run a USB power cable to.

If you do add one, be sure to add a counterweight on the opposite side of the valve stem to keep the wheel balanced.

John Salak
RV12 N896HS

 

[Bob Y]

Well, just installed a set on my 12iS yesterday and flew with them today. Seemed to work well. And not sure if there’s something different about the iS vs. legacy fork, or the model of TPMS I’m using, but I’ve got a good 0.25” clearance between it and the nose-wheel fork. It was interesting to see the drop in pressure with altitude (low OAT). The pressure readings on the TPMS matched two of my pressure gauges, so pleased with the accuracy. This model has its own receiver, which is solar charged - I didn’t want to fool with another application on my phone. There’s a skylight in my hangar so looks like it will keep it charged ok. I powered it off when I left the hanger yesterday after installing it and it did take several minutes for it to reacquire the sensors after powering up the receiver today, but it found them again. Price on Amazon was around $40. And the difference in weight between the metal-valve cap and sensor is only 5.5 g. Time will tell if it’s of value, but it’s pretty neat.

 

[MacBoat]

Well, just installed a set on my 12iS yesterday and flew with them today. Seemed to work well. And not sure if there’s something different about the iS vs. legacy fork, or the model of TPMS I’m using, but I’ve got a good 0.25” clearance between it and the nose-wheel fork. It was interesting to see the drop in pressure with altitude (low OAT). The pressure readings on the TPMS matched two of my pressure gauges, so pleased with the accuracy. This model has its own receiver, which is solar charged - I didn’t want to fool with another application on my phone. There’s a skylight in my hangar so looks like it will keep it charged ok. I powered it off when I left the hanger yesterday after installing it and it did take several minutes for it to reacquire the sensors after powering up the receiver today, but it found them again. Price on Amazon was around $40. And the difference in weight between the metal-valve cap and sensor is only 5.5 g. Time will tell if it’s of value, but it’s pretty neat.

I have TPMS and have found them useful. The ones I have use a phone app, which I don't mind, however it doesn't fit with the front fork. My nosewheel tire tube valve stem seems to be longer than yours as the TPMS monitor looks to be about the same size. Anyway, I like knowing what the tire pressures are when I perform my preflight and these work well for me.

 

[seagull]

When your tire pressure is low do you have to remove the wheel pants to add air? The lower screw is difficult to get off without lifting the plane. If you needed to add air at an airport without tools it would get frustrating.
My pants have a 1” hole with a cap that lines up with the valve stem but I don’t think I could remove the TPMS through that hole.

 

[Brett H]

Well, just installed a set on my 12iS yesterday and flew with them today. Seemed to work well. And not sure if there’s something different about the iS vs. legacy fork, or the model of TPMS I’m using, but I’ve got a good 0.25” clearance between it and the nose-wheel fork. It was interesting to see the drop in pressure with altitude (low OAT). The pressure readings on the TPMS matched two of my pressure gauges, so pleased with the accuracy. This model has its own receiver, which is solar charged - I didn’t want to fool with another application on my phone. There’s a skylight in my hangar so looks like it will keep it charged ok. I powered it off when I left the hanger yesterday after installing it and it did take several minutes for it to reacquire the sensors after powering up the receiver today, but it found them again. Price on Amazon was around $40. And the difference in weight between the metal-valve cap and sensor is only 5.5 g. Time will tell if it’s of value, but it’s pretty neat.

Thanks for your feedback. It was very helpful.

It is my understanding that the RV-12 and RV-12iS use the same nose wheel fork. That makes me wonder if the clearance between the TPMS sensor and the nose fork is depends on what inner tube is being used. Are you using the Van’s supplied Aero Classic inner tube or something else?

Thanks.

Brett

 

[Bob Y]

I too believe the nose forks are the same. I’m using the Van’s-supplied Aero Classic tubes and obviously don’t have a clearance issue, so it would seem to point to the style of sensors, as others report interference, assuming they too are using the Aero Classic tubes.

And I don’t have wheel pants, so they’re not an issue for me.

 

[Brett H]

I too believe the nose forks are the same. I’m using the Van’s-supplied Aero Classic tubes and obviously don’t have a clearance issue, so it would seem to point to the style of sensors, as others report interference, assuming they too are using the Aero Classic tubes.

And I don’t have wheel pants, so they’re not an issue for me.

I installed the same Tymate TPMS today and had the following observations:

1.) The clearance between the sensor and the inside of the nose wheel fork was an eighth of an inch. This is more than the minimum clearance between the head of tow bar bolt head and the tire. So, this should be sufficient clearance.

2.) The stated accuracy of the TPMS sensor is +/- 1.5 psi. Considering that the Van’s air pressure specification for the nose wheel is 22 - 23 psi, this accuracy is less than desired. As a side note, the air pressure specification for the main wheels is 25 - 28 psi.

3.) The display for the TPMS system only shows measured air pressure as a whole number. Namely, nothing after the decimal point. This makes it more challenging to understand changes in the nose wheel air pressure.

4.) Installing the TPMS sensor on the stem of the inner tube releases some of the air in the inner tube due to the valve being open momentarily until the sensor seals the stem of the inner tube. Thus, the air pressure that had been in the inner tube is lowered. To address this leakage I increased the initial pressure to account for air leaked during installation of the TPMS sensor.

This is what I have learned so far.

Brett

 

[Brett H]

I installed the same Tymate TPMS today and had the following observations:

1.) The clearance between the sensor and the inside of the nose wheel fork was an eighth of an inch. This is more than the minimum clearance between the head of tow bar bolt head and the tire. So, this should be sufficient clearance.

2.) The stated accuracy of the TPMS sensor is +/- 1.5 psi. Considering that the Van’s air pressure specification for the nose wheel is 22 - 23 psi, this accuracy is less than desired. As a side note, the air pressure specification for the main wheels is 25 - 28 psi.

3.) The display for the TPMS system only shows measured air pressure as a whole number. Namely, nothing after the decimal point. This makes it more challenging to understand changes in the nose wheel air pressure.

4.) Installing the TPMS sensor on the stem of the inner tube releases some of the air in the inner tube due to the valve being open momentarily until the sensor seals the stem of the inner tube. Thus, the air pressure that had been in the inner tube is lowered. To address this leakage I increased the initial pressure to account for air leaked during installation of the TPMS sensor.

This is what I have learned so far.

Brett

I wanted to update the group on my additional experience with the Tymate TPMS system.

The initial installation went well. But my additional experience didn't go well and I have stopped using it.

The Tymate TPMS system sensors that attach to the stem of the inner tube go to "sleep" after they no longer sense vibration / wheel motion to allow the batteries in these sensors last longer. Upon sensing vibration / wheel motion again, the sensors are to "wake up" and transmit to the Tymate receiver again. When the sensors go to "sleep" the display continues to show the last reading that it has received. Fortunately, these sensors transmit the measured pressure and temperature at each wheel. Since the displayed pressure is shown as a whole number and the sensor accuracy is only +/- 1.5 psi, it would require a significant pressure change for the displayed pressure to change. But, a temperature change is easier to measure and thus, could be used as check on whether the sensor has "woken up" and transmitted a new update.

The issue that I had was getting the sensors to "wake up" after the airplane sat overnight. Think of it as wanting to know what the tire pressure is when one performs a preflight inspection. One of the sensors consistently "woke up" quickly and I was very pleased with it. Unfortunately, the other two sensors "woke up" slowly or not at all. To get these two sensors to "wake up" I rolled the airplane in and out of the hangar, tapped on the sensors and tapped on the wheels without success.

I contacted Tymate to get assistance with resolving this. Tymate requested that I remove the sensors and rematch each sensor to the display. Unfortunately, this didn't resolve the issue. The one sensor still "woke up" quickly and the other two sensors were slow or didn't reconnect. Turning the display off and restarting it didn't help either. After more emails, Tymate offered to send a replacement unit after I returned my unit to them. By now I had lost faith the Tymate TPMS could be trusted to consistently report the wheel pressures and I elected to return it locally to Amazon and was refunded my money that day.

I would still like to get a TPMS system that could measure the pressure in all three tires. I'll keep looking and I am to suggestions.

Brett

 

[Piper J3]

I bought a set of four (4) TPM on Amazon and use two (2) units on main wheels of RV-12 and remaining two (2) units on my motorcycle. All four work flawlessly to measure pressure before using vehicle. I open TPM app on cell phone and place phone on pliot’s side wing walk during preflight inspection. I note tire pressures just prior to pulling the plane out of the hanger. Works a charm….

 

[Bob Y]

I wanted to update the group on my additional experience with the Tymate TPMS system.

The initial installation went well. But my additional experience didn't go well and I have stopped using it.

The Tymate TPMS system sensors that attach to the stem of the inner tube go to "sleep" after they no longer sense vibration / wheel motion to allow the batteries in these sensors last longer. Upon sensing vibration / wheel motion again, the sensors are to "wake up" and transmit to the Tymate receiver again. When the sensors go to "sleep" the display continues to show the last reading that it has received. Fortunately, these sensors transmit the measured pressure and temperature at each wheel. Since the displayed pressure is shown as a whole number and the sensor accuracy is only +/- 1.5 psi, it would require a significant pressure change for the displayed pressure to change. But, a temperature change is easier to measure and thus, could be used as check on whether the sensor has "woken up" and transmitted a new update.

The issue that I had was getting the sensors to "wake up" after the airplane sat overnight. Think of it as wanting to know what the tire pressure is when one performs a preflight inspection. One of the sensors consistently "woke up" quickly and I was very pleased with it. Unfortunately, the other two sensors "woke up" slowly or not at all. To get these two sensors to "wake up" I rolled the airplane in and out of the hangar, tapped on the sensors and tapped on the wheels without success.

I contacted Tymate to get assistance with resolving this. Tymate requested that I remove the sensors and rematch each sensor to the display. Unfortunately, this didn't resolve the issue. The one sensor still "woke up" quickly and the other two sensors were slow or didn't reconnect. Turning the display off and restarting it didn't help either. After more emails, Tymate offered to send a replacement unit after I returned my unit to them. By now I had lost faith the Tymate TPMS could be trusted to consistently report the wheel pressures and I elected to return it locally to Amazon and was refunded my money that day.

I would still like to get a TPMS system that could measure the pressure in all three tires. I'll keep looking and I am to suggestions.

Brett

Brett, sorry you made your purchase based upon my post. Mine “sleep” too after sitting over night, so yes, I pull it out of the hangar to wake them up, but have had no issue so far with them connecting to the receiver. Even after returning to the plane for departure after an hour or so layover for lunch they’re still “reporting to the receiver. After two 2-leg flights of over an hour each leg, they continue to report while airborne, since as I mentioned earlier, I can see the pressure change with decreased OAT. Guess I just got lucky with mine if you’re have connectivity issues. Hopefully you haven’t jinxed mine

 

[Piper J3]

I don’t believe it requires motion to “wake up” the TPM’s. No motion sensor incorporated in the TPM itself. They operate on low energy Bluetooth and respond when app is initiated on cell phone. As mentioned… I pull up the app and then place cell phone on wing walk while doing preflight inspection. Airplane remains stationary. After a few minutes, I return to front of plane and TPM’s have locked on and indicate readings.

 

[Bob Y]

I don’t believe it requires motion to “wake up” the TPM’s. No motion sensor incorporated in the TPM itself. They operate on low energy Bluetooth and respond when app is initiated on cell phone. As mentioned… I pull up the app and then place cell phone on wing walk while doing preflight inspection. Airplane remains stationary. After a few minutes, I return to front of plane and TPM’s have locked on and indicate readings.

These may possibly be the same regarding not needing "motion" to wake up, as I've not had much time to experiment with them yet. I'll have to play around more to see for sure.

 

[Brett H]

I don’t believe it requires motion to “wake up” the TPM’s. No motion sensor incorporated in the TPM itself. They operate on low energy Bluetooth and respond when app is initiated on cell phone. As mentioned… I pull up the app and then place cell phone on wing walk while doing preflight inspection. Airplane remains stationary. After a few minutes, I return to front of plane and TPM’s have locked on and indicate readings.

Unlike the system that you are using, the Tymate system comes with a monitor that communicates with its sensors.

Since I no longer have the manuals, I can not quote them. But, the manual stated what frequency they communicated on.

From one of my emails with Tymate, they said “Then drive your vehicle from 5 - 10 minutes in order for the monitor to start showing the readings”. The manual also said that the sensors would stop transmitting after they didn’t sense vibration for a specified number of minutes to extend the battery life. I think that it was 10 minutes.

My suspicion is that sensing vibration is what gets the sensors to transmit rather than wheel rotation. This is why in addition to rolling the airplane out of the hangar, I rocked it back and forth, ran the tire that had the sensor didn’t want to transmit over a piece of wood to create a bump, tapped on the sensor and tapped on the wheel.

Out of curiosity, is your LEEPEE sensor small enough to be used on the nose wheel? Is the FOBO sensor small enough?

Thanks.

Brett

 

[Piper J3]

Out of curiosity, is your LEEPEE sensor small enough to be used on the nose wheel?

No... interferes with nose fork.