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Tire Pressure Monitor System (TPMS)

Piper J3

Well Known Member
I bought Honeywell Tire Pressure Monitor System (TPMS) for $55 and mounted sensors on the RV-12 main wheels. There is not enough clearance on the front fork to allow using a TPMS for the front wheel. Four (4) sensors come in the package normally used on an automobile. Tire pressure and valve stem temperature are displayed on your cell phone. The sensors are designed with replaceable batteries which normally last two years. I have the other two sensors mounting on my motorcycle. For both the airplane and the motorcycle I added one square of balance weight opposite the valve stem. Individual sensor weighs 9 grams and one square of balance lead weighs 7 grams. Works a charm?

>>Moderator edit: Removed link to 3rd party online sales outlet per VAF posting rules<<

upload my pictures



 
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How much taller are they than the normal valve stem cap? I'm sure these would work on my RV10 mains but like the -12, nosewheel clearances are very tight. A friend of mine in NC has been working on just such an idea for several years but I believe his were to be slighter in profile, i.e. more easily retrofitted in a wide range of aircraft. We all hate checking tire pressures!
 
Curious

I am curious if they are strong enough for plane use. Seems an awful lot of mass hanging on a valve stem. I think I would put a blob of home depot spray foam between the sensor and the rim.
 
I am curious if they are strong enough for plane use. Seems an awful lot of mass hanging on a valve stem. I think I would put a blob of home depot spray foam between the sensor and the rim.

So far, so good. The valve stem is all metal and fastened in place with a jam nut. I think it will be fine.

I'm interested in seeing reported temps inside the wheel fairing with hot days and long taxi on asphalt. I have had brake fade on long taxi with cross wind where you have to continuously drag a brake to track centerline.
 
The FOBO website talks about using metal stems not flexible ones we'd have with tubes. They look awfully big to me and the weight, 10g, would definitely call for a counterweight, I would think. I'm no expert; only dumb enough to be dangerous.
 
Right, the TPMS weigh 9 grams. I use a "square" of wheel balance stick-on lead that weighs 7 grams to offset the TPMS on both the small airplane wheels and motorcycle wheels. Everything spinning nice and smooth with no vibration.
 
I?ve used them for close to two yrs now with tubed tires on an RV6A without using counter weights and have not had any problems. The valve stems on the tubes are metal and are clamped in place by the rim, it?s not going anywhere
 
I?ve used them for close to two yrs now with tubed tires on an RV6A without using counter weights and have not had any problems. The valve stems on the tubes are metal and are clamped in place by the rim, it?s not going anywhere

Which ones are you using, the Honeywell or the FOBO?
 
Yes, they come with metal stems but you do not need them, since we have rubber valves, you can install the sender direct on the rubber valve.
Replace your tire valve caps with the sensors and pair them according to the App’s simple on-screen instruction.
 
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These do run a more significant risk of your tire running flat more frequently, as the valve stem wasn't designed to be sealed externally. The valve that runs inside it was designed, and has worked for countless years, to seal the stem with the assistance of the pressure in the tire. This monitor completely defeats that system, in favour of reliance on the external threads and a gasket seal against the end of the valve stem.

On the plus side, it'll tell you that your tires are losing air. On the downside, you're going to be putting air in more often. Fly an RV for a year, and you'll learn what the tires look like when they are low. My $0.02.
 
Fly an RV for a year, and you'll learn what the tires look like when they are low. My $0.02.

I've done the "Visual Tire Pressure" method for many years and always guess wrong. I seem to off +/- 10 lbs. I now look at the TPMS during preflight and verify tires are at recommended pressure before launching. So far everything is hunky-dory...
 
Clearance issue with FOBO sender touching rivets on nose wheel fork

Recently installed the FOBO tire pressure monitoring system for trikes and want to first mention the monitoring system appears to work great and the FOBO App was quite easy to set up and establish parameters for the high and low pressure alarm points.

Those RV-12 owners still using the old original WD-1230 nose wheel fork can disregard the rest of this post ... you will likely not have any clearance issues installing the FOBO sensors.

The nose wheel fork on my RV-12 has been upgraded to the new WD-01230-1 nose wheel fork which requires riveting the U-00006E-L-1 mounting bracket (used to mount the wheel pants) onto the nose wheel fork. I ran into a clearance issue with the FOBO sensor touching the shop heads of the two aftmost rivets that secure the U-00006E-L-1 bracket onto the WD-01230-1 nose wheel fork.

I filed down the shop heads of the offending rivets a little and was able to get enough clearance to spin the wheel but any flexing of the valve stem would cause interference with the rivets. Not being happy with the total lack of clearance, I remembered when first installing the new WD-01230-1 nose wheel fork that the fork flexed inward about a 1/16" as the axle bolt was tightened.

Long story short I made a 1" x 1/16" washer out of .062 scrap aluminum and inserted it in the natural gap I had between the U-01210B-1 spacer and the WD-01230-1 nose wheel fork ... essentially offsetting the wheel 1/16" to the right. Now when I flex the valve stem I still have plenty of clearance.

Bottom line, if you are installing the FOBO sensors on your RV-12 and have the new WD-01230-1 nose wheel fork just because the sensor clears the fork does not mean you are good to go ... also check for interference with the aftmost two rivets that secure the U-00006E-L-1 bracket onto the WD-01230-1 nose wheel fork. Below is a link to my blog containing photos of the clearance issue I ran into.
http://www.dogaviation.com/2020/07/installing-fobo-tire-pressure-monitors.html

Edit: Return from the future.
I ended up removing the FOBO nose wheel sensor. Even with the extra clearance I created by adding a 1/16" washer to garner more clearance between the sensor and the nose wheel fork, I discovered it was not enough. With the sensor installed quite a bit of pressure needed to be applied to the valve stem to flex it enough before the sensor would make contact with the nose wheel assembly ... so I thought it would be good to go. High speed taxi testing reveled no surprises ... so I made a few touch and go's at the home field. Upon return to the hangar, I inspected the sensor assembly and could see evidence of contact, as some of the plastic on the sensor body was shaved off from contacting the nose wheel fork. The centrifugal force created by the wheel instantly ramping up from 0 knots to 35 knots is obviously much more than I would have thought. If the valve stem were secured to the wheel there would be no issue ... but that is not the case with the wheel used on the RV-12.


Happy flying,
 
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I looked into these earlier, and correct me if I’m wrong, but it didn’t appear one could set different alarm limits for the front vs. rear tires. Is that correct?
 
I looked into these earlier, and correct me if I’m wrong, but it didn’t appear one could set different alarm limits for the front vs. rear tires. Is that correct?

Not correct ... when first configuring the FOBO App I selected a single wheel up front trike configuration. After the sensors were installed and recognized by the App, I was able to set different alarm points for the nose wheel than I use for the main gear wheels.

That said, however, the two rear tires are locked ... so any settings one makes for alarm points on the right main gear wheel also applies to the left main gear wheel.
 
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Just a quick update…. Since installing these Tire Pressure Monitors (TPM) back in June, I have noticed a very slow leak in both main tires – 5psig in three months. The TPM’s work great! When I get to the hangar, I take my cell phone, turn on the pressure monitor app, and then place the phone on the pilot-side wing walk while pre-flighting the plane. Just before climbing into the plane I retrieve the phone and note the tire pressures.

The pressure sensors work by holding the internal Schrader valve open so all sealing is now done with the rubber face of the TPM against the end of the valve stem. So, the reason for this post is to explain the fix for slow air leak. I use a light coating of Parker silicone O-ring grease on the face of the valve stem to help seal the rubber against any machining imperfections in the brass valve stem. O-ring grease is really sticky stuff and works a charm…
 
Their website describes a FOBO 2 system now for trikes (for $148), 7.6g. is this what I should buy? is this reasonably a no-install system (although I understand one could counterbalance it)?
 
Their website describes a FOBO 2 system now for trikes (for $148), 7.6g. is this what I should buy? is this reasonably a no-install system (although I understand one could counterbalance it)?

I couldn't make TPM fit on front wheel - not enough clearance valve stem/fork. Some other guys have reported success using TPM on front wheel. Likewise, some folks don't add balance weights - I did...
 
I tried the Sykik tire pressure management system.

Unfortunately, it also did not fit...it would have needed just a little more clearance to the tire rim (maybe 2mm?). looked nice otherwise...
 
I tried the Sykik tire pressure management system.

Unfortunately, it also did not fit...it would have needed just a little more clearance to the tire rim (maybe 2mm?). looked nice otherwise...

Are you talking about nose wheel or main wheels? There is not enough clearance between the valve stem and front fork to allow TPM in my opinion.

I run TPM's only on the main wheels. I check tire preessures as part of every preflight. It's also interesting to see pressure loss over a period of several weeks - 2 psig in six weeks seems to be about normal.
 
Just a FYI... I noticed my tires looked a little lower this morning. Of course, the air temps in the fall are lower, than when I put new tires and tubes on the mains in early July, so the pressure has probably dropped a bit, too.


It's that time of the year, with or without monitors, to probably add a little bit of air pressure to your tires, due to temperature changes. Make sure you check yours and adjust, if you still fly this time of year.

I have to do the same on all the cars, too.
 
>> Are you talking about nose wheel or main wheels? There is not enough clearance between the valve stem and front fork to allow TPM in my opinion.

the sykik monitors fit neither my two main wheels nor the front wheel.
 
Do any of you guys happen to have a dead TPMS lying around or one that won't see use? I want to trial-fit one on the RV9A nose gear to see if I have clearance, and what if anything I would need to do to increase clearance.
 
I want to trial-fit one on the RV9A nose gear to see if I have clearance, and what if anything I would need to do to increase clearance.

Greg,

If your valve stem is secured at the wheel so it will not flex, you should be able to get by with minimal clearance. However, if your valve stem can move around when pushed with a finger (like the ones on the RV-12 wheel), then you will likely want at least a 1/4" of clearance. Read the edit in post 19 in this thread.

Happy flying,
 
Greg,

If your valve stem is secured at the wheel so it will not flex, you should be able to get by with minimal clearance. However, if your valve stem can move around when pushed with a finger (like the ones on the RV-12 wheel), then you will likely want at least a 1/4" of clearance. Read the edit in post 19 in this thread.

Happy flying,

I don't think I'll have enough room with the 9A nose gear bracket.
 

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