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Garmin GTX330 altitude encoder

Five year old GTX330 altitude output continually reads 200 feet out (just within tolerance) and occasionally throws out large errors.Any knowledge on likely cost and ease of replacement?Operating mode A only at present and searching for an avionics engineer with some capacity they all seem swamped with .833 installations at present.Regards Stampe

EGMD EGTO EGKR, United Kingdom

Hello Stampe,
Where are you based ?
It’s most likely the remote mounted encoder that is causing the problem, those are normaly easy adjustable , but should be checked using a pitot static tester.

It might be one of these or similar.

Administrator
Shoreham EGKA, United Kingdom

Thank you for your replies it’s a friends aircraft based at Rochester.Avionics annual is due in a month so that’s likely to be the first chance to get hold of an engineer they really are difficult to get at the moment!Those pictures are very interesting Peter! My own aircraft is in the queue for an avionics upgrade and I,m noticing a very high failure rate of the radios currently being installed in aircraft at my home field.Are the new designs of .833 radios inferior to the stalwarts that preceded them?Regards Stampe

EGMD EGTO EGKR, United Kingdom

@stampe it would be most interesting to know which 8.33 radios are failing.

Administrator
Shoreham EGKA, United Kingdom

Peter I will pm you with what I know rather than air the avionics industries dirty washing on a public forum! Regards Stampe

EGMD EGTO EGKR, United Kingdom

Are 8.33s more sensitive to interference? We had a problem with our Trig at first. Now long solved.

Maoraigh
EGPE, United Kingdom

Maoraigh wrote:

Are 8.33s more sensitive to interference? We had a problem with our Trig at first. Now long solved.

I don’t think so.

When I had my TY91 installed earlier this year, the installer (same company that does all other maintenance on the palne) told me that there were some faint clicks in the new radio, but that was usual because they are much more sensitive than the old ones so don’t work that well in older airframes and they could not isolate any source. Not knowing any better, I took the plane home. The faint clicks were so loud that I had a headache after 20 min flying. I also noticed that the frequency of the clicks was proportional to the engine RPM. At home on the ground I did further tests revealing that the clicks were there on the old radio (kept as emergency kit) as well with the same or higher volume and they completely went away when only the no 1 magneto was on. I therefore took the plane back and told them find the source of the clicks, which they then successfully did after ca. an hour… It was a piece of faulty insulation on an ignition cable. The problem of course went away in both radios immediately after the cable was exchanged.

All in all, IMO this “extra sensitivity” is something installers use as a myth to cover for sloppy work on their end.

Hajdúszoboszló LHHO
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