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Avionics certification

alioth wrote:

It took months for Garmin to even acknowledge the problem, which was easily demostrated, let alone issue a fix! And the certification authorities basically ignored it instead of withdrawing the transponder’s certification.

This shows it’s not that hard to get software certified. Besides, why should certification of software be such a big deal? It’s only about documenting adherence to a standard. 99% of such documentation can be re-used, and just about everything can be handled in-house, once the core development platform, procedures and testing is set. For hardware it’s a very different concept, since there is no way of producing something without additional suppliers.

The elephant is the circulation
ENVA ENOP ENMO, Norway

the Garmin transponder (GTX345) which would crash when it got 0 degrees for tracking north (exactly as the ARINC specification says it should – heading is 0 – 359, but the GTX345 wanted 1-360).

Label 320 is actually 0 to (just under) +180 and 0 to (just under) -180, with the LSB being 0.00549316 of a degree. A conversion has to be done between this and 0 to 360 and having spent some time on this it is easy to get it wrong if one is not careful. I am actually limiting the value emitted on ARINC429 to 1 LSB below 180, so label 320 will only ever get within 0.00549316 degree of 180, and pretty obviously nobody will tell the difference, but it may well prevent something downstream blowing up due to a bug. Zero itself should work fine – unless they did it totally wrong.

It took months for Garmin to even acknowledge the problem, which was easily demostrated, let alone issue a fix! And the certification authorities basically ignored it instead of withdrawing the transponder’s certification.

Garmin have in-house certification. They bought UPSAT for their ODA. I don’t know how much the FAA gets involved. But for sure nobody checks anybody’s code.

Administrator
Shoreham EGKA, United Kingdom

I personally think MCI’s is the wrong approach.

They should have pre-certified, pre-priced base configurations that only need field-configuration of parameter labelling, warning and thresholds levels upon installation.

Everything else is an unsurmountable barrier for anything other than airframe OEM or multiple-SN’s approval.

The typical customer will want it configured for his single aircraft not for his fleet of 20 aircraft, and he will want a clear price and timeline.

Do not underestimate the complexity of software compliance demonstration: there are too many process uncertainties (mostly human+organizational interface) in such approval, hence the “buying UPS-SAT” was going for a known path rather than reinventing the wheel…sensible!

Antonio
LESB, Spain

So much depends on the detail of what the product does. I don’t know anybody who knows the details but it may well be, for example, that a fuel totaliser needs no software QA at all.

That instrument in the OP is either a toy or a demo, or (cabin differential pressure!) is really critical.

Administrator
Shoreham EGKA, United Kingdom

Are there any requirements for avionics sold to the non-certified airframe market – assuming the item doesn’t fall under any of these

  • emits intentional radiation
  • is a GPS and the aircraft flies under IFR
Administrator
Shoreham EGKA, United Kingdom
15 Posts
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