Hello,
for some reason our TB-10 was not equipped with an alternate static air switch (which is odd since it even has a stormscope) – this is required for IFR operation according to the POH supplement.
Anybody got an idea if its possible to retrofit an alternate air switch (in the best case a generic one to avoid Daher pricing) under EASA rules somehow?
Thanks!
@ultranomad may know.
I am not a Socata specialist, but the POH for TB-10 mentions “alternate static source (if installed)” in emergency procedures, and the type certificate allows IFR operations if a sufficient kit of optional equipment is installed. Thus, the installation of an alternate air switch does not constitute a change to the type design. For practical considerations, one should see the parts catalogue, which I don’t have at hand. To avoid Daher’s pricing, you can try finding a generic switch that’s totally identical to Socata-branded one, but it may be easier just to get a used Socata switch from an aircraft dismantler.
From the airworthiness standpoint, this should be a simple paperwork exercise, but discuss it with your CAMO/CAO/airworthiness inspector first.
Thanks for the info! I’ll try to aquire the part in question (TB3077010000) – maybe I am indeed lucky and get a used one somewhere.
The TB20 alternate air selector looks like one of the many Socata parts which look “homemade” and most probably come from the French homebuilt parts industry.
A lot of those firms are tiny and many don’t even have a website. Consequently they are hard to find with google. The mfg will also be contracted to Socata to not sell directly, and most totally refuse to communicate when they recognise a part they sell to Socata. Google is anyway poor for finding French parts; you need a French person using French Google.
On the plus side, this switch is almost never touched so any part from a breaker should be fine.
https://www.ebay.at/itm/134169630658
How about that one ?
That looks like it but it seems to be badly damaged
Peter wrote:
On the plus side, this switch is almost never touched so any part from a breaker should be fine.
You don’t check the switch at preflight or startup?
Thanks for the pointers, Socata asks for 982 Euro for the whole thing with 120 days delivery time.
While I searched on ebay and various other platforms and didn’t come across the part linked above for some reason, so also thanks for that! I also learned of a TB10 that is parted out in EDLP – maybe I can grab it there.
Ultranomad wrote:
Thus, the installation of an alternate air switch does not constitute a change to the type design.
In Canada, it would:
(e) Other Qualities Affecting Airworthiness
Does the modification or repair:
…..
(2) alter any information contained in the approved section of the aircraft flight manual or equivalent publication?
……
(10) affect instruments, or indicators that are installed as part of a system required by the approved type design? Quote
Though fairly benign, an alternate static air system requires a flight manual reference to any possible instrument errors which occur when the valve is open (to alternate air) and the correct positioning of cabin ventilation/windows open, relative to instrument indications.
If you install the OEM kit in accordance with the parts catalog, and the flight manual contains the required information already, you’re set, it’s not a modification (the data is there already). otherwise, it’s a modification, which requires approved data (so a change to the type design).
