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Can an STC override more basic legislation?

Let’s say there is a regulation which says that a non TSOd product cannot be connected to an autopilot.

Let’s say that Vendor X manages to obtain an STC for an autopilot, and the STC contains a list of stuff which can be connected to it, and the list includes stuff which is not TSOd.

Is that STC legit?

Obviously an STC application is checked by a certification agency (FAA or EASA) but they can fail to spot something small.

Administrator
Shoreham EGKA, United Kingdom

As far as I understand (please correct me if I am wrong), TSO is never mandatory, it merely simplifies the approval for the given configuration, somewhat like CS-STAN, but to a lesser degree.

LKBU near Prague, Czech Republic

Peter wrote:

et’s say there is a regulation which says that a non TSOd product cannot be connected to an autopilot.

Can you find a real world example? Regulations generally don’t say things like that.

Yes, you can do that. Good examples are the MORE program for the PT6 (TBO extension) and the Petersen Mogas STC (fuel limitation removal). Both basically suspend the manufacturers overhaul limits or fuel limitations.

My understanding is that a TC or STC includes everything in the package, in combination, without regard to individual component certifications. Another good example is the use of low quality engine gauges in type certified aircraft – they are often not something that could be TSO’d.

Another good example is the use of low quality engine gauges in type certified aircraft – they are often not something that could be TSO’d.

I think that’s different – because they get approved under the airframe manufacturer’s TC.

Can you find a real world example? Regulations generally don’t say things like that.

Not sure I can find one which says that directly, but it seems implied by various scenarios. For example you cannot get a Field Approval for installing an uncertified instrument anywhere, not even on the RHS and out of primary view. Some have got these but the general view appears to be that it was an FSDO error. But you can install “anything certified” provided it is “monitoring only” and especially no autopilot connection. It is a long tradition…

There are bogus STCs. For example the K&N air filter STC for the TB20 is bogus. It fits only the TB10. You can get such STCs because nobody is going to verify it physically.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

I think that’s different – because they get approved under the airframe manufacturer’s TC.

The TC is a government controlled document that can be supplemented by anybody, under the same requirements as the holder of the base TC, if that organization still exists. I don’t think the original airframe manufacture has special status in relation to the TC, at least not under FAA regs. If an STC is added to a TC the combination is in effect, the additional process is subject to the same technical requirements as the original data and I don’t think anybody involved gets any special treatment.

BTW, before the odd (and rather perverted ) current trend of having STCs to perform simple equipment installations came along, an STC was for only significant changes to the design, by anybody. That is part of the reason why the entire package is subjected to approval, an STC was never intended to be slightly more than a minor mod, using TSO approved off the shelf parts.

Last Edited by Silvaire at 19 Mar 14:28

TSO only eases the certification work for the TC/STC applicant. But there is no problem at all to certify a design using non-TSO equipments.

LECU - Madrid, Spain

But there is no problem at all to certify a design using non-TSO equipments.

Let me take one example. How would you go about certifying an autopilot whose user interface is an Ipad?

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

How would you go about certifying an autopilot whose user interface is an Ipad?

For the sale of discussion let’s say a DER completed an 8110-3 including an iPad. Would that not do it? The only issue is that he wouldn’t likely that because it’s not suitable for that job, regardless of TSO status.

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