BeechTalk - BT - FAA Grounds Citation 525s With Tamarack Winglets

Username Protected · **Posted:** 26 May 2019, 17:35

Didn’t see a thread on this.

https://www.flyingmag.com/faa-grounds-c ... kSdT27FWoQ

Username Protected · **Posted:** 28 May 2019, 20:32

Yikes! Ferry for repairs is restricted to FL250 or below and 140-160 KIAS.

Username Protected · **Posted:** 28 May 2019, 21:57

Couple of years ago at the Embraer Owners convention, we were giving Embraer a hard time for not starting a test program with Tamarack. Well... maybe they were right.

Username Protected · **Posted:** 28 May 2019, 22:09

Username Protected wrote:

Didn’t see a thread on this.

It got buried in this thread unfortunately, and I don't think many read it.

https://www.beechtalk.com/forums/viewtopic.php?f=41&t=160842&p=2402957&hilit=tamarack#p2402957

Username Protected · **Posted:** 29 May 2019, 08:24

This is "interesting": Tamarack Active Winglets 101

Quote:

Passive Winglets require significant structure (weight) to reinforce the wings due to winglet-induced loads during certain flight conditions. Active Winglets are designed for maximum aerodynamic efficiency—without compromises that come with additional loads and strengthening structures. Tamarack’s Active Winglets feature innovative load-alleviating technology (ATLAS®) that “dumps the load” when conditions require. This allows for a wing extension and an optimally sized winglet. With the ATLAS® Active Winglet and wing extension, planes save 3 to 4 times more fuel than any passive winglet.

Why do I see so many winglets on so many airliners?

Because winglets work! Fuel is the second largest expense for airlines, so they are always looking for innovative ways to reduce fuel consumption. And as people begin to think more seriously about their carbon footprint, winglets make air travel a more environmentally friendly option. Major airlines wouldn’t install them without realizing a solid ROI.

Username Protected · **Posted:** 29 May 2019, 08:56

In order to be able to dump all of the lift created by the Atlas winglet, the active control surface is quite large. If an error causes the Atlas control surfaces to fully deflect in opposite directions, it is easy to understand why it would be difficult to control the airplane. The autopilot could do this same thing with the primary control surfaces but you can overpower the AP while hitting the red button to disconnect it. Atlas doesn't have an easy to reach red button and doesn't have a way to overpower it.

As far as I know, this is Tamarack's only product. I'm sure sales have stopped. If they fix this, I'm not so sure sales will start again. A CJ2 is a perfect candidate for winglets and I was thinking about getting them if our budget allowed but I am glad I didn't. It will be difficult for Tamarack to make me comfortable with their winglets after all this but I hope they figure this out and thrive again - it is a wonderful idea.

Username Protected · **Posted:** 29 May 2019, 09:38

Username Protected wrote:

In order to be able to dump all of the lift created by the Atlas winglet, the active control surface is quite large.

It is worse than that, the active winglet has to generate NEGATIVE load in the worst case gust situation to alleviate the entire spar load. That's because not all of the winglet is being actively controlled (so you have to cancel the static part) and because adding a winglet makes the end of the stock wing also work better at generating lift. So the active control surface is large and powerful.

This is from the Tamarack patent showing the negative load required:

Attachment:

winglet-lift-1.png

Mike C.

Username Protected · **Posted:** 29 May 2019, 11:40

Username Protected wrote:

In order to be able to dump all of the lift created by the Atlas winglet, the active control surface is quite large.

It is worse than that, the active winglet has to generate NEGATIVE load in the worst case gust situation to alleviate the entire spar load. That's because not all of the winglet is being actively controlled (so you have to cancel the static part) and because adding a winglet makes the end of the stock wing also work better at generating lift. So the active control surface is large and powerful.

This is from the Tamarack patent showing the negative load required:

Attachment:

winglet-lift-1.png

Mike C.

Username Protected · **Posted:** 29 May 2019, 12:08

I'm completely guessing, but suspect they have some sort of closed-loop control system that (a) senses vertical gust loads and then (b) commands opposite/load-dumping deflection of their control surface before the full magnitude of the gust load is generated (it is a function of time).

The theory is that existing wings are deigned with gust loads as required by the FARs, and by adding winglets (or straight wing extensions) the center of the lift load moves outboard and thus increases the maximum bending moment at the wing root. If they have the load-dumping control system, then they should be able to reduce the new gust loads enough to stay within the original wing design envelope and thus avoid adding structure (and weight, cost) to the wing...just bolt on the winglet and go.

Username Protected · **Posted:** 29 May 2019, 12:37

ah...so you are saying that gust loads are not instantaneous and the electronics/motors can react fast enough to protect the spar from overload. Ok, I get that.

I wonder if the system is designed to over-react in anticipation of further increasing loads? Is this why the system can produce twice as much downforce as the winglets lift?

Username Protected · **Posted:** 29 May 2019, 12:49

I'm not convinced the system can dump twice the load that the winglet generates...I think it only needs to dump the additional winglet load and then the wing is back to original design. Look at Mike C's chart...the area under the curve above and below the zero line at the tip appear to be roughly equal, so the net result is the original lift distribution.

Username Protected · **Posted:** 29 May 2019, 13:39

They are finished. No insurer will touch them with a 10ft pole after the claims for the two crashes are paid out assuming they had any major liability insurance to begin with. I'm willing to bet the issue in the end will be a software flaw just as it was in case of the 737MAX. Maybe they can add some explosive bolts to it. That's the only way I'd get on a jet with this system.

Username Protected · **Posted:** 29 May 2019, 13:50

Username Protected wrote:

Maybe they can add some explosive bolts to it. That's the only way I'd get on a jet with this system.

I'll take my Bonanza if that is the case.

Username Protected · **Posted:** 29 May 2019, 15:08

Username Protected wrote:

They are finished. No insurer will touch them with a 10ft pole after the claims for the two crashes are paid out assuming they had any major liability insurance to begin with. I'm willing to bet the issue in the end will be a software flaw just as it was in case of the 737MAX. Maybe they can add some explosive bolts to it. That's the only way I'd get on a jet with this system.

Did I miss something? I am only aware of one 525 that went down, and I thought that the cause was not yet determined.

Username Protected · **Posted:** 29 May 2019, 17:22

Username Protected wrote:

They are finished. No insurer will touch them with a 10ft pole after the claims for the two crashes are paid out assuming they had any major liability insurance to begin with. I'm willing to bet the issue in the end will be a software flaw just as it was in case of the 737MAX. Maybe they can add some explosive bolts to it. That's the only way I'd get on a jet with this system.

What if you trigger the "explode the winglets off the plane" and only one side blows off?

I only know of one CJ crash where the winglets are a suspect. But I the point is the same. Three people died and if the winglets were to blame, I imagine the lawsuits will wipe Tamarack out.

They've installed winglets on about 95 C525s. If Rick gave up on them this quick...will the Tamarack folks give up that easy too? If they do give up, who will pay to develop the fix or the deinstall kit? How long will it take?