Avery selling replacement flap pushrods

Avery selling replacement Hex flap pushrods

http://www.averytools.com/pc-923-80-flap-rods.aspx

Pre cut, drilled and tapped.



No way am I using that thin little tube that Vans sent with the kit.

The flaps on my -9.

Vans shipped my kit with the hex material for my -9 kit.

Kent

7/9 pushrods

the 9's come with the hex stuff. i ordered a pair of 9 flap pushrods for my 7a. the partnumber (according to my notes) is VA-256.

That thin little tube is all ya really need, the hex stuff weighs more.

Rivethead said:

That thin little tube is all ya really need, the hex stuff weighs more.

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I'll give you the same speech that I gave my freind Chad on the other forum...

Making them is easy, I just do not think the factory ones are up to snuff. By the time you tap them, they are too thin for my engineering mind. Having a flap fold up on short final is not something I want to experience. I know, I know, I know... Where is a case in the 6K flying RV's of this happening? Don't know but I do not want to be #1.

Vans sells these as well untapped for $12 bucks each. Thats $28 for the set after the $4 buck box charge. I'll give Avery the $2 to cut, drill and tap these on a lathe. It is worth it to me, plus they are good people.

**edit** unconfirmed but someone mentioned on the other forum that these are $15 bucks a pair so that makes them even more of a value.

I don't want to say that everyone should use these, only that this is what I am doing. To each their own...

e

Brantel said:

Making them is easy, I just do not think the factory ones are up to snuff. By the time you tap them, they are too thin for my engineering mind. ..

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Even to aero engineers, things don't always look right ...thats why they test.

The push rod as designed has been tested. I don't know what the failure load was but it seems to me I heard that it was more than three times the load expected from tha flap that is used on the two seat RV's. Except for the RV-9(A) which has a much larger flap. Which was the reason the heavier pushrod material was used.

Brantel said:

Having a flap fold up on short final is not something I want to experience. I know, I know, I know... Where is a case in the 6K flying RV's of this happening? Don't know but I do not want to be #1.

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If that is your attitude, you might consider another hobby. Just that there are many other places you might do better and there is always the weakest place somewhere. By correcting 'everything' a bit you easily add additional weight without even noticing it... Pilots makes a lot of errors as well so hopefully you are experienced as well.

Pirkka said:

If that is your attitude, you might consider another hobby. Just that there are many other places you might do better and there is always the weakest place somewhere. By correcting 'everything' a bit you easily add additional weight without even noticing it... Pilots makes a lot of errors as well so hopefully you are experienced as well.

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Hahahhahaa, wow, I wan't to replace my flap push rod with a better one and all of a sudden you think I should find another hobby! Hahhahahaa, nope don't think so. This thread has nothing to do with pilot competence, not sure how that has anything to do with with flap push rods.

Bottom line is, you build yours your way and I will build mine my way and after all, obviously more people than me are buying or concidering buying these or there would not be a market for them and Avery would not be selling them.

Q!

Brantel said:

Hahahhahaa, wow, I wan't to replace my flap push rod with a better one and all of a sudden you think I should find another hobby! Hahhahahaa, nope don't think so. This thread has nothing to do with pilot competence, not sure how that has anything to do with with flap push rods.

You're right, your thread has NOTHING to do with pilot competence. I've got 650 hours and many, many landings with those "thin little tubes" so Van's did a good job testing them and keeping them as light as possible and still very, VERY functional and safe.

Ahhhhhhhh........I get it now! Your thread has EVERYTHING to do with re-engineering a fine product. Let's see, is that why we have the EXPERIMENTAL class? Dream on and build it YOUR way, but be safe!

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Brantel said:

Hahahhahaa, wow, I wan't to replace my flap push rod with a better one and all of a sudden you think I should find another hobby! Hahhahahaa, nope don't think so. This thread has nothing to do with pilot competence, not sure how that has anything to do with with flap push rods.

Bottom line is, you build yours your way and I will build mine my way and after all, obviously more people than me are buying or concidering buying these or there would not be a market for them and Avery would not be selling them.

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Brian, Well said and thank you for letting us know they are available for purchase. After all, that is what the original post was about.

replace the adjusters

Neil Crotts from Dodge City had one of the stock pushrod adjuster tubes break on a RV6 in the flair. It's lucky he caught a wingtip and cartwheeled instead of rolling inverted before the crash. Call Crotts Aviation in Dodge City to confirm, anyone there will have a opinion on the stock pushrod adjusters.

I have bought two RV's and the adjuster is the first thing that gets replaced. The strong adjusters will only add ounces.

SteveKs.

rvbuilder2002 said:

e

Even to aero engineers, things don't always look right ...thats why they test.

The push rod as designed has been tested. I don't know what the failure load was but it seems to me I heard that it was more than three times the load expected from tha flap that is used on the two seat RV's. Except for the RV-9(A) which has a much larger flap. Which was the reason the heavier pushrod material was used.

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Yeah...and I wonder why some RVs out there have 1000s of hours on them with no flap pushrod failure... Wonder what the factory demo planes have on 'em... hm... I'm guessing the STOCK design!

I think there are at least 2 problems at work here, both of which lie in the builder's hands:

1. Drilling and tapping the pushrod properly. First of all, did the builder drill a proper clearance hole before tapping? Did the builder drill that STRAIGHT? If the hole wasn't drilled straight, it could leave a thin area in one spot on the wall of the pushrod -- essentially a stress riser. Wonder where it's gonna break if it does...

2. Rigging the flaps. If you allow the pushrod to be in TENSION when the flaps are retracted, i.e. the flaps are tugged up to the point where they're forced tightly against the fuselage by the PULLING, not by the FIT...well, that probably contributes to some degree.

I know several builders at Chino who opted to replace the aluminum with steel (of the same size) -- some from the get-go, and others at some point along the way...after having flown and, as Scott points out, tested.

I also know one RV-8 builder with whom I fly weekly...he did have one aluminum pushrod fail at ~250 hours (iirc). It was a non-event that he, as a terrific pilot, handled calmly. I wasn't able to see the part after the failure to get a sense of whether #1 or #2 above played into it. Wish I had been able to see it. He replaced it with steel tubing, and of course he preached doing the same to all of the local RVators...understandably.

My RV-7 with 1400+ hours still has the bone stock aluminum tubes, which I drilled & tapped in my garage. I *KNOW* I did not drill 'em perfectly straight, but I am not losing sleep over it.

I'm not trying to convince people NOT to use the larger hex stock pushrods. I actually think it's a great idea for builders who aren't confident that they can do a "good enough" job with the stockers. Scott, your point about testing is valid to me, but you gotta consider "the worst builder" out there. A factory-built pushrod may have been tested, but was "the worst built" pushrod tested?

I think I'm just seeing this argument from both angles, and at this point I'm just babbling...

How do they fail?

Can someone explain HOW they fail?
Seems to me they are in compression while they are deloyed, so do they actually bend from the air pressure, which could be pretty good at 100mph?

I could imagine (hopefully only imagine) what it would be like to have one flap come loose from the rod during the landing phase.

oh, and does anybody know how long the rods are on the RV-6?
Avery lists them for the 4,7, 8.....but not the 6.
Thanks

What is the weakest link?

I believe that I have read somewhere (here?) about someone extending their flaps to fast, or maybe is was retracting them to late. Anyway I believe it was the flap hing that was needing replacement no the rod. Can anyone confirm?

Kent

Avery Responds

Brantel said:

Vans sells these as well untapped for $12 bucks each. Thats $28 for the set after the $4 buck box charge. I'll give Avery the $2 to cut, drill and tap these on a lathe. It is worth it to me, plus they are good people.

**edit** unconfirmed but someone mentioned on the other forum that these are $15 bucks a pair so that makes them even more of a value.

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Hey guys

I apologize, the shopping cart is pretty vague on the quantity for $15.

It is in fact a PAIR for $15.

The RV 6 per the plans is 3.5 inches long. We don't have these made, but Bob could make them pretty easily. However lead time may be a week due to shop load. Same price. We just dont have alot of demand for those.


I will fix the web page on that one.

changed

ok its been made a bit more clear on the site.


anytime you see a booboo like this let me know.

KenAvery said:

Hey guys

I apologize, the shopping cart is pretty vague on the quantity for $15.

It is in fact a PAIR for $15.

The RV 6 per the plans is 3.5 inches long. We don't have these made, but Bob could make them pretty easily. However lead time may be a week due to shop load. Same price. We just dont have alot of demand for those.


I will fix the web page on that one.

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I just measured mine (RV6A), and they are 4 7/16" long. Very little threads on the rod ends are showing, though. I guess I made them to fit, without having to screw the rod ends out much.

L.Adamson

Two other builder problems I have run across is "bending" the push rod and or inefficient clearance causing the push rod to scrape the fuselage skin. Both of these are extreme NO-NOs.

Mel said:

Two other builder problems I have run across is "bending" the push rod and or inefficient clearance causing the push rod to scrape the fuselage skin. Both of these are extreme NO-NOs.

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Mel is right.
Of the two failures that I am aware of, one was caused by the tubes having been bent by the builder to clear the opening (not a smart thing to do on a member loaded in compression.
The other was because of a tube repeatedly rubbing on the opening (read that, repeatedly ignored during preflight inspection).

Van addressed this very issue a number of years ago in the RVator. He came across as a bit peevish and stated explicitly that the flap actuator rods had been engineered and tested to withstand the design loads. Eyeball engineering can be deceiving. It is very seductive to "beef up" a structure just because it looks like it needs it. But, excess strength means excess weight, which subjects the remaining structure to unnecessary loads and actually weakens the whole. The excess weight also means reduced performance. Years ago I knew a man who built a Stewart Headwind with VW power. At every turn he made the airplane stronger than called for in the plans. The airplane was seriously overweight and would barely fly. He sold it before the summer was out. Building light requires real discipline. We put our faith in the designer's competence and integrity. I can understand why Van might feel peevish when his calculations and tests are questioned.

Vans part

L.Adamson said:

I just measured mine (RV6A), and they are 4 7/16" long. Very little threads on the rod ends are showing, though. I guess I made them to fit, without having to screw the rod ends out much.

L.Adamson

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vans part number is va-257. They are longer than you need for any model. I used them when I wanted to drop the flap handle to the floor. They were threaded deep, so I could cut them where needed.

I did like the fact that you could use a wrench on the flat sides. Oh yes, they were about an ounce heavier than the tube in the kit.