TPIS system A320

[alberthmann]

Hi mechs, During my last shift, it was quite boring and I decided to know a little bit more about the TPIS system.
I searched in the AMM and in the Technical Training manual about alpha call up label for the TPIS but I didn't found it.


I know we can have the value of the speed of a wheel using an alpha call up label and I was wondering if we could know precisely the value in PSI of a wheel using the MCDU. (Not on ECAM)


However, I founded in the TPIS MCDU system report test page, a “ref pressure “
One for the NLG and one for the MLG.
What's the meaning of a “ref pressure”
thanks

Fly safe,

[TURIN]

No idea.

I shouldn't worry about it if I were you as most of the a/c I know have had it disconnected.

[Terry McCassey]

We had a customer A320 arrive at our station recently with 60psi indicated on the ECAM wheel page written up in the logbook. A quick visual showed nothing abnormal but when checked with a direct reading gauge, it was indeed down to 60psi. We lived with the ensuing delay while we changed the 2 wheels knowing that ignoring it could have been much much worse. Without TPIS I doubt even the most Line seasoned veteran would have spotted a problem. Well done and thank you TPIS.

[SeldomFixit]

Would reference pressure be the nominal " normal " pressure ?

[MATMAX]

Bravo SeldomFixit !
Alberthmann , may i suggest you to spend some more time in the books ...?

[flame_bringer]

from the AMM:
Nominal Pressures and Detection Threshold

Nominal inflation pressures are given for the nose and main gear wheels.
The pressures are wired on the rear connector (Pin programming). A 6 bit code:
-
programs the pressure of each wheel,


-
gives an adjustment range from 9 to 15 bars by steps of 2 psi (Approx. 0.15 bars) for the main wheels and from 8 to 11 bars for the nose wheels.


Aquisition of the six tire pressures (Table)


-------------------------------------------------------------------------------
| Normal Inflation Mode |
|-----------------------------------------------------------------------------|



| Main and Nose Wheels |
|-----------------------------------------------------------------------------|
| Absolute Pressure | Differential Pressure |
|---------------------------------|-------------------------------------------|
| Comparison of each tire pressure| Comparison of the pressure of the two |
| with an absolute minimum | wheels on the same axle. The difference is|
| threshold. This threshold is | given in % (ROM) in relation to the |
| given in % (ROM) in relation to | highest value of the two pressures |
| the nominal pressure wired at | concerned. |
| the computer connector. | |
|---------------------------------|-------------------------------------------|
| Takeoff | Flight + Landing | Takeoff | Flight + Landing |
|--------------|------------------|------------------|------------------------|
| Main | Nose | Main | Nose | Main | Nose | Main | Nose |
| wheels|wheels|wheels| wheels | wheels| wheels| wheels | wheels |
| 11 % | 11 % | 26 % | 26 % | 15 % | 15 % | 21 % | 21 % |
-------------------------------------------------------------------------------

[flame_bringer]

4
"REF PRESSURE" item

(Ref. Fig. 013 SHEET 013.1)
This item contains the values of the reference pressures wired at the back of the computer rack.

[flame_bringer]

(1)
Pressure warning

The TPIS computer sends a pressure warning to the upper ECAM DU. This warning is function of the result of the comparison of the tire pressure with the absolute and differential pressure thresholds.
(Ref. Fig. 008 SHEET 008.1)
The faults are memorized in a nonvolatile memory. The tire pressure warning is inhibited during takeoff when the aircraft speed is higher than 80 Kts

[flame_bringer]

buttom line:

By pin programming the connector at the back of the TPIS computer you set up a nominal pressure to each wheel for the low pressure warning threshold, the ref pressure function in the system reports and test simply tells you the current pin programming configuration and the pressure thresholds currently set up.
I hope that helps.
If you need further clarification feel free to pm