Why are TPMS not allowed on certified aircraft

[MooneyMitch]

18 hours ago, Yetti said:

Schrader valves are not designed to keep air pressure in, that is what the caps are for.

I believe the only function of the cap (aka dust cap) is to keep contaminants out of valve area.

[Yetti]

3 minutes ago, MooneyMitch said:

I believe the only function of the cap (aka dust cap) is to keep contaminants out of valve area.

So when I remove the front tire cap I hear a little pssst.   So I know it is doing it's job.

 

A valve cap is important on a Schrader valve to prevent dirt or other contaminants from affecting the sealing surfaces and causing a leak.

Metal, and some hard plastic valve caps, have a rubber washer inside both to prevent the cap from loosening and falling off due to vibration and serve as a mechanical seal to help slow air from escaping from a leaking valve core.

In refrigeration and air conditioning applications, the valve cap is considered to be the primary seal, with the Schrader valve only being used for service access.

[philiplane]

A few years ago, Cirrus owners were using a screw on TPMS system (not approved of course) and then the fad died when they found the system was unreliable in reporting pressure, and in many cases, was leaking air from the tires. 

The best way to avoid flats is to check pressure post flight, and also to install new Michelin Air Stop inner tubes every 5 years. 

[GeeBee]

We can argue about the purpose of a Schraeder valve or the cap all we want. This fact remains. A properly functioning Schrader valve should not leak, and a MS20813 cap in good condition, properly installed should not leak. Together they form a double barrier system and they should be used....together.

 

[MooneyMitch]

49 minutes ago, GeeBee said:

We can argue about the purpose of a Schraeder valve or the cap all we want. This fact remains. A properly functioning Schrader valve should not leak, and a MS20813 cap in good condition, properly installed should not leak. Together they form a double barrier system and they should be used....together.

 

This is a very serious discussion!! It’s quite possible this issue could make its way all the way to the Supreme Court....

My opinion only, with a car, motorcycle, bicycle small ga airplane, etc tire.... if you begin twisting off a dust cap and you hear a psssst, yes, the little dust cap is indeed holding the air, but ya sure got a leaky valve which needs to be addressed sooner than later.  I would not depend on a normal little rubber/plastic cap to provide any confidence.

Again, my own personal preference. 
 

[Hank]

1 hour ago, MooneyMitch said:

This is a very serious discussion!! It’s quite possible this issue could make its way all the way to the Supreme Court....

My opinion only, with a car, motorcycle, bicycle small ga airplane, etc tire.... if you begin twisting off a dust cap and you hear a psssst, yes, the little dust cap is indeed holding the air, but ya sure got a leaky valve which needs to be addressed sooner than later.  I would not depend on a normal little rubber/plastic cap to provide any confidence.

Again, my own personal preference. 
 

Yep. I put an inexpensive set of colored caps on my Tacoma, that are supposed to change color [green-yellow-red] if the tire develops a leak. Three days later, undriven, all four tires were between 20-25 psi. Threw them away, put the original caps back on after airing them all back up.

My Mooney does not have "normal little rubber/plastic cap" on any tires, they are all hexagonal metal caps painted yellow, I think.

[GeeBee]

Those yellow metal caps would be MS20813 caps.

 

https://www.aircraftspruce.com/catalog/lgpages/valvecap.php

 

 

[MooneyMitch]

1 hour ago, Hank said:

My Mooney does not have "normal little rubber/plastic cap" on any tires, they are all hexagonal metal caps painted yellow, I think

Mine too ! 

[Yetti]

3 hours ago, MooneyMitch said:

This is a very serious discussion!! It’s quite possible this issue could make its way all the way to the Supreme Court....

My opinion only, with a car, motorcycle, bicycle small ga airplane, etc tire.... if you begin twisting off a dust cap and you hear a psssst, yes, the little dust cap is indeed holding the air, but ya sure got a leaky valve which needs to be addressed sooner than later.  I would not depend on a normal little rubber/plastic cap to provide any confidence.

Again, my own personal preference. 
 

Informed people don't run little plastic caps.   I have always run metal caps on the cars/ trailers.

[MooneyMitch]

7 hours ago, Yetti said:

Informed people don't run little plastic caps.   I have always run metal caps on the cars/ trailers.

Consider me informed 

[carusoam]

Oddly I feel informed now... but...

on one of my cars... the metal cap with rubber gasket/seal also had a decorative shiny stem cover....

I’m guessing the stem cover is going to cut its way through the stem one day... somehow...

-a-

[MooneyMitch]

Ok, ok, I guess my cars have cool little shiny caps too.  One of them has the shiny stem covers too.

[MooneyMitch]

I’ve never been quite so interested/aware and now completely informed on Schrader valve dust caps.... until Mooneyspace...... I love this place 

So, here’s a photo of one of my wheels with the shiny little metal dust caps and shiny little stem sleeve...... super cool looking indeed!!  and, inside the cap is an little orange colored gasket.... I guess it’s for sealing in that little pssst sound when I remove it.... except mine didn’t go pssst. 

Anyway, I’m installing new tubes and tires on my little M20 beauty today...... and reinstalling my little yellow dust valve caps too!! 
 

Happy day to all ! 

[Yetti]

My grandfather and then my dad would always check the tires on my car.   Missing valve cap was noted and made an issue of.   They also were in charge of fleets of 200 trucks.  Yes those all had metal caps on them.

[MooneyMitch]

1 hour ago, Yetti said:

My grandfather and then my dad would always check the tires on my car.   Missing valve cap was noted and made an issue of.   They also were in charge of fleets of 200 trucks.  Yes those all had metal caps on them.

It’s always in the details.  Safety first.  

[MooneyMitch]

Super cool..... new caps came with new tubes