Service Alert

[jdmcbean]

Service Alert

[PapuaPilot]

Thanks John, that's a great reminder.

[Delta Whisky]

A great point, well made.

[Maverick]

So, would adding vortex generators be a change like the memo describes?

[AMK53]

I think he’s referring to airfoil or camber changes and causing changes to lift behavior of the wing. Vortex Generators don’t really change the lift curve all that much.

[PapuaPilot]

I think he’s referring to airfoil or camber changes and causing changes to lift behavior of the wing. Vortex Generators don’t really change the lift curve all that much.

True, that is what the Service Alert addresses, but the underlying issue is a statement that is put in the operating limitations of experimental aircraft. They say something like: After incorporating a major change as described in § 21.93, the aircraft owner is required to reestablish compliance with § 91.319(b) and notify the geographically responsible FSDO of the location of the proposed test area. The aircraft owner must obtain concurrence from the FSDO as to the suitability of the proposed test area.

§ 21.93 Classification of changes in type design.
(a) In addition to changes in type design specified in paragraph (b) of this section, changes in type design are classified as minor and major. A “minor change” is one that has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. All other changes are “major changes”.

The real question about vortex generators is "would it be a major change"? Unfortunately the FAA does not define it clearly other than the statement in 21.93, and a Major Change is not the same as a Major/Minor alteration on certified aircraft. But if any change appreciably affects the operation (flight) characteristics it is a major change and the aircraft is required to go back into Phase I flight testing, typically for 5 hours.

All this to say I believe VGs would be a major change. Isn't the goal is to change the flight characteristics of your aircraft? You won't know until you test fly the aircraft. It could be better, worse, no change or downright unsafe. This is the bottom line of the Service Alert that Kitfox just posted.

FYI one of the presenters earlier this week on the EAA Homebuilder's Week said that VGs are a major change. I can't remember who said it, but the statement stuck in my mind because I am considering VGs on my horizontal stab.

[n85ae]

I would imagine the downside of being a manufacturer, is that you get called every time somebody terminates their
existence with your product. So you would be quite inclined to formally say - This is what we designed, it's safe,
don't change it. If you do, you're on your own.

I'm not sure I would ever even consider selling my airplane, simply because I don't want to have anything to do
with what somebody might do with it in the future after it left me.

Pretty obvious watching YouTube video's that a percentage of people flying Kitfoxes are stupid.

Jeff

[Eric Page]

I either read in one of the experimental aviation magazines, or heard in a webinar, that no builder has ever been sued (or was it, "successfully sued?") for an accident by a subsequent owner in an aircraft they built. I don't know the truth of that assertion, but maybe someone else remembers the reference.

[jrevens]

It’s “successfully”, and it’s been stated many times in print. Even if “unsuccessful” you will probably have to spend a fortune to defend yourself if it happens. Having sold an airplane that I built (from “scratch”), I can say that there are ways to drastically minimize the possibility. One of them is not having made structural changes that deviate from the original proven design. The proper legal sales agreement, as well as being very careful about who you sell to are others. Of course we all know that anyone can sue anybody for anything in our world.

[109JB]

I can tell of one where a lawsuit was brought. Wasn't successful but I'm sure it cost the guy a boatload in legal fees anyway. Look up John Denver's Long EZ accident. The original builder, who deviated from the build plans with regard to the fuel selector, was sued, but If I remember right, that suit was eventually dropped. Denver's Long-EZ (check-six.com) (http://www.check-six.com/Crash_Sites/John-Denver-N555JD.htm)

[Delta Whisky]

Combining Jeff's input with Paupa's - we build these planes and obtain and maintain an AW cert by following the rules. One of the rules in our experimental airworthiness certificate says that 14CFR 21.93 applies (in mine it is in para 14). So, if one were to add anything in hopes that it would alter a flight characteristic(s), putting the plane back into phase one and performing and documenting the required tests should put you back in exactly the same certification/legal position you were before the mod - wouldn't it? To me it boils down to: any and all changes made during construction were incorporated in the EXP AW certificate (phase 1, et al) and any changes made later maintain the same level of authorization if they are made IAW the rules.

[109JB]

Valid, but it depends on your operating limitations. For example, my Sonerai, which got its airworthiness in 1992, says nothing about notifying the FAA after major repairs, alterations, changes in flight characteristics, etc. It also says nothing about FAR 21.93. Likewise, the Kitfox 4 1050 that I previously owned also had op lims that said nothing about major repairs, alterations, or modification of flight characteristics. Those op lims got superceded when I applied to change the n-number, which required a new airworthiness.

Not that it isn't a smart thing to do flight testing after a potential change, but not all airplanes require notification of the FAA for something like adding vortex generators.

[alexM]

I think this bulletin is aimed less at VGs and post build modifications, and more aimed at modifications like the Snake River Bushplanes "piggyback ribs", slats, etc.

Those changes definitely affect the flight characteristics. From a product liability standpoint I don't blame the factory at all for distancing themselves from mods like those.

The only way they could stand behind aftermarket modifications like that is to test/evaluate at their own expense, and why would they? They already offer a proven product with two different airfoil choices.

[jmodguy]

I asked my FSDO rep about mods that would require a return to phase 1 and was told there are 2 things that will drive a return to phase 1 and notification of FSDO. These are a fixed pitch to constant speed prop, and a swap from piston to turbine engine.
That said-
We know all FSDOs interpret the rules exactly the same too... right!?

[airlina]

When I added Skis to my Series 5, the local FSDO came to the hangar (2 hour drive) for an inspection ( the guy didn't have a clue about ski installation and to be honest I think they just need to get out of the office so any excuse will do) and put me back into a 5 hour test phase .

[jmodguy]

When I added Skis to my Series 5, the local FSDO came to the hangar (2 hour drive) for an inspection ( the guy didn't have a clue about ski installation and to be honest I think they just need to get out of the office so any excuse will do) and put me back into a 5 hour test phase .

I know airlina! And back to my comment on FSDOs and interpretation! :eek: It's almost like a crap shoot as to what response you may get.

Anyone know what drove John to post this? I don't do youtube and am a little leery of the danger guys. That kind of stuff is what kills us on insurance rates.

[avidflyer]

Funny thing about the skis being considered a major change. When we first got our Aeronca Chief, because it had never been on skis before, we had to have the AnP do the first install and do a weight and balance for it. After that, the owner can change back and forth between wheels and skis with a log book entry. And that's on a certified plane which is far more restrictive then an experimental. Maybe the FAA guy was wanting to take a look at a Kitfox and get out of the office as well. Actually since about 1990 or so, major changes didn't require the FAA to inspect the aircraft like it did previous to that time. Would be interesting to know what the FAA guy was really thinking. JImChuk

[airlina]

Jim, Apparently not much. He was the same guy who came out with an FAA gal to do my airworthiness initial inspection. I wanted them to give the plane a good going over , but that was not to be as they were more concerned that my paperwork was correct and thats where the majority of the time was spent. Turns out after the guy did my ski inspection , he was leaving my house and wrecked and totaled the FAA's car on my 1/2 mile long private driveway by driving so fast (its a 15 MPH road) he couldn't make a turn went into the woods and tore the bottom out on stumps. I had to drive him back to the FSDO office, but it was worth it to see what he had to go thru from the rest of the office staff when we went inside. They nicknamed him Stumpy. Bruce N199CL

[jmodguy]

Ha ha ha ha ha ha ha!!!!

[Delta Whisky]

Jeff - there is a chance the FSDO gent misunderstood the question - he might have been thinking "What alteration on an experimental requires a 8130-6?". For that his answer is correct.