Prandtl multi probe receptacle used for TE only?

On Wednesday, February 14, 2018 at 6:57:27 PM UTC-5, JS wrote:
They're a pain to replace.

Yup, IMHO a huge design blunder to put the O-rings in the socket
instead of on the probe. I once asked SH how to replace the O-rings,
and they said they have absolutely no idea ;-(

How to change the internal O-rings is all explained in the service section of the ESA Systems web page. That's not to say it is easy - or even possible in the case of ring 3 without removing the socket which means cutting open the fin.

The probes and sockets are produced by esa-systems in Berlin. There's an instruction on how to replace the O-rings on their website: https://www.esa-systems.com/en/suppo...i-change-them/

Now tell me again...
Why aren't the O rings on the probe?

Must be an oversupply of engineers needing to design something like this O ring insertion tool.

Don't ask me.

There are two videos on YouTube explaining the process: https://www.youtube.com/watch?v=NitQF9Of4fk https://www.youtube.com/watch?v=a91LM2JIF0s

torstai 15. helmikuuta 2018 15.29.25 UTC+2 kirjoitti:
Now tell me again...
Why aren't the O rings on the probe?

Must be an oversupply of engineers needing to design something like this O ring insertion tool.

If the grooves for O-rings were in the probe it becomes quite weak at the base. Aluminium or brass develops crack at groove area because TE probe vibrates a lot. My guess: they discovered that probe with O-rings/grooves did not last too long. BTW, one-way TE probe has usually a groove and O-ring in the probe. It cracks sometimes but it is easy to glue a new base part to an old probe. With two- or 3-way probe this is impossible.

On Thursday, February 15, 2018 at 4:26:46 PM UTC, krasw wrote:
torstai 15. helmikuuta 2018 15.29.25 UTC+2 kirjoitti:
Now tell me again...
Why aren't the O rings on the probe?

Must be an oversupply of engineers needing to design something like this O ring insertion tool.

If the grooves for O-rings were in the probe it becomes quite weak at the base. Aluminium or brass develops crack at groove area because TE probe vibrates a lot. My guess: they discovered that probe with O-rings/grooves did not last too long. BTW, one-way TE probe has usually a groove and O-ring in the probe. It cracks sometimes but it is easy to glue a new base part to an old probe. With two- or 3-way probe this is impossible.

That makes sense. Unlike the triple probes the ESA TE/Static double probes use the ST2 socket and the probe has a short aluminium (I think) insert with O -rings on it. I had one of those break in flight at an O-ring groove inside the socket. Part way through the task I lost the ability to thermal properly and didn't understand why until I landing and found the probe drooping about 30 degrees and being held by the probe internal flexible tubing..

I contacted ESA directly and they repaired the probe very quickly for a very reasonable cost.

Sure wish ESA would redesign their UN and SUN adapter to offer a "screw-off" front end which could be exchanged when o-rings become faulty. Hey ESA, want to make more money?