Peter wrote:
Here it is with a couple of areas I highlighted which make me not understand how anything that e.g. drives an autopilot can possibly not be Major
If we take the top highlighted area, then a change to an altimeter doesn’t have any effect on the basic cert basis of the product (the aircraft). It’s still a Part 23 light aircraft and the altimeter change has no effect on the basic design or certification at that level. If we proposed to add floats or different wingtips, then it could impact flight characteristics so that would make the answer YES and push it to an STC
The altimeter does not provide inner loop control to the autopilot (basic attitude stabilisation, pitch/bank limiting, runaway control etc) so doesn’t create a potential hazardous/catastrophic failure condition. Even if the altimeter gave a false altitude or baro-correction output and the autopilot tried to fly to it, the basic pitch attitude limiting controls within the autopilot inner-loop would limit the available pitch demand, and the pilot is also monitoring what’s going on and has other cues to determine if there are obvious errors.
Now if we proposed to change the attitude source then it would probably be a different story as we’d have to assess the failure modes and probabilities of the attitude gyro/AHRS giving duff information which could possibly be un-annunciated (so perhaps the aircraft could exceed the autopilot design pitch/bank angle limits as it wouldn’t have a true reference).
When making the major/minor assessment we have generated a check-list based on this table and don’t just provide a tick-box response but have to justify the decision-making process so that it’s transparent on audit.
In our Part 21J we have specific privileges on autopilot sensor integration as discussed above, but we can’t do a total autopilot certification currently. Even if we could, it would require equipment OEM involvement for flight test of runaway conditions and sorting airframe gain programming, and would certainly be an STC
Thanks, wigglyamp. I found your flow chart here [ local copy ]
Here it is with a couple of areas I highlighted which make me not understand how anything that e.g. drives an autopilot can possibly not be Major
Peter wrote:
So IMHO the EASA “minor change” route is meaningless for comparing with the FAA “minor alteration” route – because a customer will judge this according to how much it cost him.
As I said previously, an EASA MINOR change is equivalent to an FAA MAJOR alteration. Both require approved data, In the case of US-aircraft, either approved by the agency via a FSDO-signed Form 337, a DER-signed 8110-3, or for Europe, approved by an EASA Part 21J or directly by EASA.
An FAA MINOR change is equivalent to CS-STAN and in both cases some doccumentation is meant to be raised to justify the decision. For EASA we use the EASA Form 123. The Aircraft Electronics Association produce some excellent guidance for the FAA A/P on determining what he can consider to be acceptable as a Minor change.
An STC is a Major change to type design (not a Major Alteration) and has the same meaning and approval process both in the EU and US. One advantage the US currently has which speeds up the process and reduces costs is the ODA (Organisational Design Approval) such as held by major manufacturers. whereby they can make their own determination of compliance and issue STCs directly using internal processes. A similar process is on the way for Europe.
Cost has no bearing on modification classification. For EASA, the determination of Major/Minor (when it’s definitely outside the scope of CS-STAN) is determined by following the flow-chart in 21A.91:
Peter wrote:
The GNS WAAS STC would have cost a few k to the customer who had it originally done and the Part 21 avionics
If it would be a one off STC sure, but that would be the same with an one off FAA STC.
Peter wrote:
the Part 21 avionics shop then sells it to other avionics shops.
In those case the pricing is normally much lower, as the cost are shared over multiple users. This is IMHO the reason why Wigglyamp has asked a couple of times feedback if a certain modification would be interesting. I did ask the same for the Robin – Aspen STC, which is now on its way.
Peter wrote:
That’s a different list you posted this time
Sure, the first list was to show what is possible as a minor change. Custom made STC or minor change for one S/N will always be more expensive then one where data can be re-used. For example with the HF it included mounting an HF antenna, which requires strength calculation and EMC testing. The same for 3D camera systems. These are one offs, and use non aviation equipment, and thus far more design work, then it requires for a mode C to mode S upgrade, that isn’t strange is it?
Again, this would be similair on N reg. If you want an HF transceiver with tuner and antenna in your aircraft, you would need to spend time and thus money on the design. This doesn’t change with EASA or FAA.
Ok, so the WX systems (stormscopes) and TAS systems where all included in the quotation, and wouldn’t be near 1K even including the 290 Euro EASA fee.
That’s a different list you posted this time, Jesse 
And some of it is almost a “velcro job” e.g. the Golze or Flarm products. Little more than the installation of an extra circuit breaker.
The GNS WAAS STC would have cost a few k to the customer who had it originally done and the Part 21 avionics shop then sells it to other avionics shops. That’s if it was done that way; wigglyamp may have done it initially on his own account.
Peter wrote:
That would be highly relevant, if it means one could replace a primary instrument with a different (functionally same i.e. an encoding altimeter with a different presentation but which has the same gray code output) type, even though the aircraft TC specifically calls out the original. In FAA-land you need an STC for that, specifying “primary replacement”
Did you read CS-STAN? Under EASA you can often use CS-STAN, in other cases a minor change is enough.
You don’t seem to understand, that if you want to change anything from the TC or and applicable STC, it isn’t always a major change, as you seem to suggest all the time. The change can be minor of major. Cases like these a minor changes.
Peter wrote:
I spoke to one UK shop today and they said the same – an EASA STC is currently needed
You always spoke with a shop which doesn’t seem to understand any regulations as all. IMHO you just seem to be bashing EASA, installers or shops, all the time. Many of us have proved over and over again that you statements don’t make sense at all.
wigglyamp wrote:
but you do like to knock the EASA mod system and praise the FAA approach when in fact they’re not that different anymore
I agree with this, and really can not understand why you have related ALL of EASA, mechanics etc… You keep on this over and over and over.
Peter wrote:
I would have to be a complete idiot to think that particular “minor change” cost the customer less than thousands just in the design paperwork that goes to EASA to support the application!
Ok then I don’t charge enough I guess. Then if I would you would likely argue that monkeys are charging $$$ for a simple design. For a minor change it is never near 1K at my, which includes the 290 Euro EASA fee.
For example, the Golze WX solutions, can be issued with a minor change. Does these cost thousands on minor change? No
Another example, Garrecht TRX can be issued with a minor change. Does these cost thousands? No
Flarm products could be bought with a minor change, Did these cost thousands? No (no covered in CS-STAN)
Using the GNS-WAAS STC Wigglyamp worked on. Does this cost thousends? No, not even close
Trig TT-31 installation, minor change free of charge.
JP Avionics voltwage warning light. Does this cost thousands? No
The altimeter minor changes I did, did these cost thousands? No
The altimeter minor changes Wiggly amp did? I wouldn’t think it would be thousands.
You wanting a PT-6 engine on your TB-20 without excisting STC, would this be major? Yes, would this be thousands? Yes you wouldn’t come near it with paperwork for that for a few thousand.
Peter wrote:
In the EASA-land “minor mod” scenarios described here, the customer pays thousands. So to call it a “minor mod” is not exactly accurate – especially if the poster then goes on to suggest that the EASA route is much better than the FAA route (a Major mod would be needed in most of the FAA cases)!
Ok, so I showed you it doesn’t cost thousands. Why doesn’t understand EASA the term minor mod? I think it is very logical. Calling an altimer check, or as you describe anything that is on an TC or STC, so basically changing anything from orginal as a major, that wouldn’t make sense IMHO.
I can not comment on the FAA requirements, maybe @Wigglyamp can. I think they are much more similair then you pretend them to be. And if the FAA actually requires an STC for changing an altimeter, then I would suppose it would be fair to say the EASA system, on this point, is clearly more suiteable for GA.
Thanks for the clarification.
you do like to knock the EASA mod system and praise the FAA approach when in fact they’re not that different anymore (excluding Agency fees).
I ask straight questions and they can be answered with a straight answer.
Some people think I am trying to make points. Sometimes I am, but subtlety is not my forte, and much more often (and in this case) I just happen to know a bit about the topic and am just structuring the question carefully to elicit an answer which reveals something that I think isn’t being revealed 
And I do sense that there is a certain amount being left out, which would confuse the hell out of most people who don’t know much about this.
In FAA-land, a “minor mod” usually means an A&P/IA looks at it and decides it is a minor mod, and it goes in with a logbook entry. The FAA provides a fairly easy flow chart for this (yes I know there are various subtleties e.g. EFIS needs an STC). The paperwork costs the customer peanuts. Well, maybe a few hundred $ for some hours of somebody’s time, but this is unlikely because the “business” is done face to face and doesn’t involve an external agency and providing you pick TSOd products you don’t need to do anything special in documentation.
In the EASA-land “minor mod” scenarios described here, the customer pays thousands. So to call it a “minor mod” is not exactly accurate – especially if the poster then goes on to suggest that the EASA route is much better than the FAA route (a Major mod would be needed in most of the FAA cases)!
Take this “minor mod” from Jesse above
- Installation of multiple 100 Watt HF systems, including tuner and antenna on unpressurised aircraft
These were HAM amateur radio HF transceivers which where modified to work on clients own frequency, this included testing emissions as well, as it required modification to frequency and filters. As such this equipment didn’t come with installations other then for amateur use. The same for the tuner. The antenna was designed for aviation use, though not for this specific aircraft. So own design, which also included EMC testing and functional in air testing.
I happen to have spent enough days in EMC labs getting my electronic designs tested and I would have to be a complete idiot to think that particular “minor change” cost the customer less than thousands just in the design paperwork that goes to EASA to support the application!
So IMHO the EASA “minor change” route is meaningless for comparing with the FAA “minor alteration” route – because a customer will judge this according to how much it cost him.
To argue otherwise is to argue e.g. that I could install a PT6 engine in my TB20. The process is completely straightforward. It’s been done before… PA46s, Bonanzas, Cessnas, you name it. Really completely straightforward. Just throw a pile of money at it… (sarcasm doesn’t work on the internet but I am sure you get my drift).
What I am getting at is that EASA doesn’t seem to have a real “minor mod” process at all. Whichever way you do it, either you have to deal with EASA (and they decide) or you deal with an EASA 21 company (and they decide, within the limits of their authorisation to do minor mods). The former route can be quite cheap (a few hundred, IIRC) if you do the paperwork yourself (most customers can’t). The latter route might be, or not, but based on what I have seen it will be way more than a few hundred especially in the cases given as previous examples.
The days of the EASA Part 21J doing mods for GA is rapidly diminishing as equipment OEM’s get more AML STCs approved
That is indeed true but this is a long-ongoing process which benefits users equally under both systems, because most AML STCs (well, the ones from the big avionics names) are done for both regimes, for new products.
CS-STAN is going through an amendment at present which is going to provide a much a greater scope including replacement of primary instruments including the addition of electronic versions provided they meet the relevant TSO.
That would be highly relevant, if it means one could replace a primary instrument with a different (functionally same i.e. an encoding altimeter with a different presentation but which has the same gray code output) type, even though the aircraft TC specifically calls out the original. In FAA-land you need an STC for that, specifying “primary replacement”, AIUI. I spoke to one UK shop today and they said the same – an EASA STC is currently needed for such a substitution.
I jest Peter, but you do like to knock the EASA mod system and praise the FAA approach when in fact they’re not that different anymore (excluding Agency fees).
CS-STAN has brought an approach very similar to the FAA minor change – acceptable data only, not approved data, and certified just with a logbook entry.
FAA Major alteration equivalent to EASA Minor change – both require approved data.
FAA Major change to type design equivalent to an EASA Major change – both require approved data and are finally approved by the appropriate agency.
The days of the EASA Part 21J doing mods for GA is rapidly diminishing as equipment OEM’s get more AML STCs approved, so it’s only the unusual or specialised tasks that will be done by the design organisation. CS-STAN is going through an amendment at present which is going to provide a much a greater scope including replacement of primary instruments including the addition of electronic versions provided they meet the relevant TSO.
Peter wrote:
One does a Minor mod allright but pays a few k for it
Peter, it is the same as asking you to publish your schematics including sourcecode firmware, stating that it is only worth 50 Euro on parts, while you sell the equipment for more. Sure you have to make a living, so do we.
The margin on equipment is nowhere near a few k, especially if you think of it that design is included.
If you want to do it yourself, you will be free to do so. On ELT’s this is good example, where someone finds a lower price ELT then quoted, then it is USA pricing, shipping as dangerous good, programmed incorrectly, no design data. Then they apply for minor change themselfs, only to find out it will be rejected a couple of times. End result is that pricing is far more expensive then when they have bought from a capable avionics shop.
I think I am beginning to understand how this works…
One does a Minor mod allright but pays a few k for it
Peter doesn’t believe in paying for approval paperwork, whether an 8110-3 or god forbid an EASA minor change.
A somewhat disingenuous statement, but you know you can count on me not disclosing private communication supporting my position
