Vortex generators – why aren’t they universal?
They are claimed to have no cruise speed downside, and big upsides for low speed behaviour.
I know one Twin Com pilot who got his installation EASA approved (as a Major Mod) though to be fair he was intimately familiar with the way EASA works and was able to do it himself, paying (IIRC) only the EASA fee.
In some cases they seem to be just stuck on, over the existing paint.
What kind of approved data does one need to generate to support the Major Mod application (EASA or FAA)?
Peter wrote:
What kind of approved data does one need to generate to support the Major Mod application (EASA or FAA)?
You can’t do a major mod yourself. It can only be done trough a DOA. DOA’s are in different levels, and depending on the level they have different levels of complexity they can do.
So either he was DOA or he got it approved as minor change (more likely). I have never received a quotation for DOA work (avionics) below 10.000 Euro. A major change is basically a custom designed STC.
In the Meridian they allow a higher MTOW but definitely reduce max cruise speed by 3-5 knots.
It reduces also the stall speed by few knots…
So you could make the wing shorter and regain some of those few knots, but then your stall speed would go up again.
Perhaps it’s just simpler to have a slightly longer wing. I would worry about them getting constantly bent/knocked off.
Peter wrote:
I know one Twin Com pilot who got his installation EASA approved (as a Major Mod) though to be fair he was intimately familiar with the way EASA works and was able to do it himself, paying (IIRC) only the EASA fee.In some cases they seem to be just stuck on, over the existing paint.
What kind of approved data does one need to generate to support the Major Mod application (EASA or FAA)?
I am indeed that twincom pilot and did the VGs in 2005.
The firm involved is Micro Aero on the west coast. They have FAA STCs for fitment to about 500 types and are very savvy about getting their STCs validated by other regulators. On my request, they applied to EASA for validation of their STC for a PA-30. To the very best of my knowledge, this validation did not cost them anything other than the time to produce the required documentation. This may well have changed by now. I had the VGs fitted as a minor mod.
The VGs are stuck on top of the paint. They will all fall off as and when the paint is stripped and Micro Aero supply “respray kits”. On my aircraft, one got knocked off during cleaning in the last 10 years.
Micro Aero are a wonderful firm with which to do business – highly, highly recommended.
OK, Alan, so you followed the route to an EASA STC whereby they accept the data used to obtain an FAA STC.
There is now a proper treaty for this. Of course EASA is not actually obliged to accept anything; the treaty is just a statement of intent 
This route has, as you found, been available for some years, but the key issue with it, which many have found, is that the aircraft owner cannot apply. One needs the FAA STC holder to make the application. And the vast majority of US firms don’t see Europe as a big enough market. You seem to have found one which was a great exception.
Peter wrote:
There is now a proper treaty for this. Of course EASA is not actually obliged to accept anything; the treaty is just a statement of intent
One needs the FAA STC holder to make the application. And the vast majority of US firms don’t see Europe as a big enough market.
Perhaps now with the bi-lateral treaty supposedly making the process much easier, the US Companies can now be persuaded to apply ?
I often wondered if they might be a problem in icing conditions…. Some ice might accumulate around these thingies. Although: their frontal area is really small. Are there any FIKI planes with vortex generators? Cessna Caravan?
Peter wrote:
OK, Alan, so you followed the route to an EASA STC whereby they accept the data used to obtain an FAA STC.
Peter – this is nearly right, but not completely so. The process is probably best described as a “piggyback” STC (a bit like a 61.75 piggyback PPL). The validation was of the FAA STC itself – not the creation of an EASA STC using the FAA data.
Michael wrote:
Perhaps now with the bi-lateral treaty supposedly making the process much easier, the US Companies can now be persuaded to apply ?
Expanding one’s approvals into Europe is still seen as a bit of a big deal for FAA STC holders for questionable gain. A lot of good STCs are held by very small companies. A good fuel pump STC for twincoms is held by a flight school, for example. The principle of automatic approval by EASA of FAA STCs is on EASA’s agenda and will, in my opinion, happen in time.
boscomantico wrote:
I often wondered if they might be a problem in icing conditions…. Some ice might accumulate around these thingies. Although: their frontal area is really small. Are there any FIKI planes with vortex generators? Cessna Caravan?
Plenty of Micro Aero’s STCs are for FIKI aircraft e.g. King Airs, C421, Senecas etc. It’s worth remembering that rime ice favours tight radii, which is why you see ice on an OAT probe before the wing leading edge. However, Micro Aero claim the following:
Ice does not form far enough aft of the leading edge to affect the Vortex Generators. We have confirmed this through extensive flight testing in severe icing conditions, per FAA flight testing requirements.
In my view a nasty case of clear ice would run back as far as the VGs, but this would be around their bases. I have never seen ice anywhere near the VGs on my twincom.
