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MarkCFI

Well Known Member
I have an RV6 with the electric flap kit installed. I did not build it.

Took an x-country down to MD this morning and on the return flight to my home field when I went to deploy the flaps the aircraft started to roll.

I stopped the flaps and could see that the left flap was only down a little bit and the right flap was down further so I retracted them which they did.

I made a no flaps landing and when in hangar tried to deploy and it looks like the left flap is stuck. I can’t be 100% sure to be honest but that’s what it looks like.

I started to pull the covers off the console between the seats where the flap motor live but won’t be able to really get to it until tomorrow. I downloaded the electric flap install doc and have that.

In addition to where the flap motor lives what other location should I check first?

Thanks in advance. Other than that good trip to Carrol County.
 
I'm fairly sure the 6 & 7 E-flaps are similar.... the up/dn motor controls a torque tube which runs across the backs of the seats - inside the baggage compartment side covers are links connecting the torque tube ends to the Left & Right flaps. Take these covers off & inspect the links that penetrate the fuselage floor connecting to the flaps. Also check the lower link attachments to the flaps.
 
Very unlikely that your problem is at the motor, since as was said above, the single motor controls the torque tube, and the flaps drive off the end of that. Look at the pushrods and where they attach to the flap and the torque tube - something has to be broken (or disconnected).
 
MarkCFI said:
I have an RV6 with the electric flap kit installed. I did not build it.

Took an x-country down to MD this morning and on the return flight to my home field when I went to deploy the flaps the aircraft started to roll.

I stopped the flaps and could see that the left flap was only down a little bit and the right flap was down further so I retracted them which they did.

I made a no flaps landing and when in hangar tried to deploy and it looks like the left flap is stuck. I can’t be 100% sure to be honest but that’s what it looks like.

I started to pull the covers off the console between the seats where the flap motor live but won’t be able to really get to it until tomorrow. I downloaded the electric flap install doc and have that.

In addition to where the flap motor lives what other location should I check first?

Thanks in advance. Other than that good trip to Carrol County.
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I would suspect an issue with the left flap rod/torque tube. You should not have differential flap movement with something seriously wrong. Take the side covers off in the baggage area and inspect both right and left flap attach rods, bearings and the flap tube bearing mounts. Might as well check the flap motor as well and make sure the SB is done for lock wiring the rod end.
 
AZSteve053 said:
I'm fairly sure the 6 & 7 E-flaps are similar.... the up/dn motor controls a torque tube which runs across the backs of the seats - inside the baggage compartment side covers are links connecting the torque tube ends to the Left & Right flaps. Take these covers off & inspect the links that penetrate the fuselage floor connecting to the flaps. Also check the lower link attachments to the flaps.
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Yes, the 6 & 7 (and 9 I assume) flap mechanism is the same. Probably even identical parts.
Once you open the box on the side of the baggage compartment (offending side) you'll find the problem.
Please let us know what you find!
 
Good advice above.

All owners, even if not builders, should have a copy of the aircraft build drawings! They are quickly and cheaply purchased from Van's and, once in your possession, will make troubleshooting (and better yet, understanding) your plane so much easier. At the very least, your A&P will appreciate them if they are not familiar with RVs.

In this specific instance, the drawings will tell you the part numbers and materials you will need to fix what is very likely a bent or broken pushrod on the offending side and/or interference between the pushrod and fuselage that prevents full travel.

Good luck with the repair
 
alpinelakespilot2000 said:
Good advice above.

All owners, even if not builders, should have a copy of the aircraft build drawings! They are quickly and cheaply purchased from Van's and, once in your possession, will make troubleshooting (and better yet, understanding) your plane so much easier. At the very least, your A&P will appreciate them if they are not familiar with RVs.

In this specific instance, the drawings will tell you the part numbers and materials you will need to fix what is very likely a bent or broken pushrod on the offending side and/or interference between the pushrod and fuselage that prevents full travel.

Good luck with the repair
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Pretty sure for no $$ you can have the aircraft build number changed to your name on the Vans web site, so you have access to the plans for free.
 
Thanks for the info.

I’ll be pulling them off tomorrow and taking a look.

I do have the drawings but for whatever reason the plans only seemed to show the manual flap setup.

Thanks again
 
MarkCFI said:
Thanks for the info.

I’ll be pulling them off tomorrow and taking a look.

I do have the drawings but for whatever reason the plans only seemed to show the manual flap setup.

Thanks again
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Torque tube & flap linkage is similar setup for both electric &manual flaps. Look at the levers & link on the torque tube by the side skin. Your problem is possibly a jammed or bent link.
 
My bad.

I looked at the drawings again (thanks Ralph and others) and suspect the area I need to look at is the F-659 link and or the connections on either end. The ball end bearings , nut and bolts, etc

I also have the instructions for the electric flap kit and after looking at them again based upon the comments in this thread there appears to be a great picture of what I suspect the problem area is.

Again, really appreciate the guidance. I guess I know what I’ll be doing tomorrow.

PS: I’ve been trying to keep my speed up until the last minute as I make the final descent to the airport. It was a good experience seeing just how tough it is to slow down without the flaps. Invaluable.
 
Well.

Again, thanks for the quick direction. I think I found the problem.

I’m wondering if this lost cleco might have anything to do with it?

IMG_0336.jpeg
 
Also, I would strongly encourage you have a qualified person do a CI now.
Your airplane obviously hasn’t had a proper inspection and this may just be one instance. Don’t let someone else’s mistakes kill you!
 
Your lucky to find that. There has been plenty loss of life incidents with tools and other stuff jamming flight controls. On another note, there have been a couple flap torque tube weldments that cracked. Take a good look at everything just in case the jamming stressed the rest of the wedment. These "learning" threads are good reads for all builders and buyers.
 
Learning experience for sure.

Nothing looked bent and I checked the flap angle with this gizmo so I think I’m good to go.

Appreciate all the help.

IMG_0337.jpeg
 
I’m surprised the cleco as shown could have cause the asymmetric flap deployment. Absent a bent pushrod, it seems like anything preventing one flap from going down should have prevented the other as well. Or, is there really that much torsional flex across the length of the steel flap weldment?
 
alpinelakespilot2000 said:
I’m surprised the cleco as shown could have cause the asymmetric flap deployment. Absent a bent pushrod, it seems like anything preventing one flap from going down should have prevented the other as well. Or, is there really that much torsional flex across the length of the steel flap weldment?
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Just to be clear, there was only a partial deployment of the right flap. As soon as the plane started to roll I retracted the flaps. I could not see a bend and as far as I could tell nor did the fully extended angle seem to differ but I can certainly order a new one.

Good info.
 
MarkCFI said:
Just to be clear, there was only a partial deployment of the right flap. As soon as the plane started to roll I retracted the flaps. I could not see a bend and as far as I could tell nor did the fully extended angle seem to differ but I can certainly order a new one.

Good info.
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You have to fabricate it, or order the new hex rod for both sides. You will need to make sure there is clearance in the fuselage cut out as the hex rod is larger diameter.
 
JonJay said:
You have to fabricate it, or order the new hex rod for both sides. You will need to make sure there is clearance in the fuselage cut out as the hex rod is larger diameter.
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Or another option is to replace the push rods with 4130 heavy wall tubing. That's what I did 32 years ago.

P.S. I wish I had a quarter for every cleco I've found while inspecting aircraft! Including those that have been riveted inside the structure.
 
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Please check the WHOLE flap system. There is no way that you could get asymmetrical flap deployment unless SOMETHING IS BROKEN. IF NOTHING is broken,That lost cleco would have effected BOTH flaps. I DON'T THINK YOU HAVE FOUND THE PROBLEM YET!
 
Fred.Stucklen said:
Please check the WHOLE flap system. There is no way that you could get asymmetrical flap deployment unless SOMETHING IS BROKEN. IF NOTHING is broken,That lost cleco would have effected BOTH flaps. I DON'T THINK YOU HAVE FOUND THE PROBLEM YET!
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I disagree.. the weldment that connects the left and right flaps is very weak in torsion. Put your flaps half down and push up or down on one arm of the weldment and you’ll see what I mean. It’s like wet tissue paper. I can totally see that cleco inhibiting the movement of one side, and the other side continues down.
 
Taltruda said:
I disagree.. the weldment that connects the left and right flaps is very weak in torsion. Put your flaps half down and push up or down on one arm of the weldment and you’ll see what I mean. It’s like wet tissue paper. I can totally see that cleco inhibiting the movement of one side, and the other side continues down.
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My RV-7A flaps are quite rigid for one side to the other. If your torque tube between the left & right flaps has that much movement ( in a steel tube) SOMETHING IS WRONG. (maybe a weld joint is broken & moving) There should be a SOLID CONNECTION FROM LEFT TO RIGHT FLAP PUSH RODS. Maybe the arm to the push rod weld joint is broken on one or both sides. Maybe the torque tube between the left & right aircraft sides has a broken weld joint. If your weldment moves like a wet tissue paper, SOMETHING IS WRONG.
Please have an experienced RV'er look at your plane BEFORE you fly it again.....
 
Taltruda said:
I disagree.. the weldment that connects the left and right flaps is very weak in torsion. Put your flaps half down and push up or down on one arm of the weldment and you’ll see what I mean. It’s like wet tissue paper. I can totally see that cleco inhibiting the movement of one side, and the other side continues down
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Please tell me how you would get flap torque tube movement "like wet tissue paper" from the weldment shown below...
1719170339787.png


There are THREE welds on this part, one on the center actuator (which if broken, would effect BOTH flaps the same), and one on each flap pushrod actuator. I suspect that the right side pushrod actuator (or the pushrod itself is defective), OR the flap is defective...... Unless this part has been modified (and the modification is failing)The chances of the torque tube twisting (a steel tube) are rare.
That stuck cleco may have caused the right actuator weld joint to break........ which would explain why you're seeing what you describe above.....

ALL of these components should be thoroughly inspected to find out why you're getting "wet tissue paper" tension on your flap.
 
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I'm leaning toward the side of caution and agreeing with Fred. Somethin' ain't adding up. Either the pushrod deflected or the flap actuator weldment deflected. All should be inspected thoroughly. And you're not necessarily looking for a bend--there could be a crack on one of those weldment arms that's allowing deflection. If you're not sure what to look at, please, please get a trusted RV builder, A&P, or a Technical Counselor to look with you. A crack could be on the underside of that weldment arm, which would be difficult to see without mirrors and a good light...possibly even a borescope that can articulate around. Take the seats out and get in there to take a good look.

Regarding Mel's comment about finding misplaced objects, looking in every single bay and cavity in the fuselage and wings is part of my annual CI. You never know when a fastener, tool, or some critter nest could have gotten in there. Those bays are easy to inspect with lights and mirrors and worth the effort. The most peculiar thing I've found is a 3/4" Craftsman wrench in a wing bay (not in my plane, but another RV that shall remain unnamed). To this day, we have no idea how it got there. But that wrench got to fly more than I did for a year or so.
 
There is no way any CI from the time this aircraft was blessed for flight, to now, included inspection and lubrication of the flap rod ends. When the cover is off, you can easily see everything.
I would be calling out whomever signed this aircraft off. They are dangerously incompetent.
 
D-Dubya said:
I'm leaning toward the side of caution and agreeing with Fred. Somethin' ain't adding up. Either the pushrod deflected or the flap actuator weldment deflected. All should be inspected thoroughly. And you're not necessarily looking for a bend--there could be a crack on one of those weldment arms that's allowing deflection. If you're not sure what to look at, please, please get a trusted RV builder, A&P, or a Technical Counselor to look with you. A crack could be on the underside of that weldment arm, which would be difficult to see without mirrors and a good light...possibly even a borescope that can articulate around. Take the seats out and get in there to take a good look.

Regarding Mel's comment about finding misplaced objects, looking in every single bay and cavity in the fuselage and wings is part of my annual CI. You never know when a fastener, tool, or some critter nest could have gotten in there. Those bays are easy to inspect with lights and mirrors and worth the effort. The most peculiar thing I've found is a 3/4" Craftsman wrench in a wing bay (not in my plane, but another RV that shall remain unnamed). To this day, we have no idea how it got there. But that wrench got to fly more than I did for a year or so.
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All good advice and appreciated.

I looked the arm, ball ends, bearing block and flaps rods over pretty good. Could not see any bends or cracks in any of the components. I had to pull the seats as it was a struggle to get the screws out of the side panel without doing that. Really tough to get on the screws reaching over the back of the seat back cross bar.

I do have access to the guy that built my 4 and can him or my A+P take a look as well. Easy to get a second opinion while open.

I was concerned with the flap attach rod and the torque tube arms getting bent so I checked that both flaps were up in the same position together and were both at the same angle when deployed. They seemed to be.

My flap position switch does not automatically stop going up or down. The flaps do but if I hold the switch up (or down) I can still hear the motor running when the flaps have reached the stop position in either direction..

So curious if that motor system has some kind of slip clutch in it? Else I would suspect it would just hum or blow a fuse if I held it in position.

EDIT: read the instructions for the flap kit and see that the actuator has a disengagement when it reaches its limit. That would explain that.


Thanks again for the advice.
 
D-Dubya said:
I'm leaning toward the side of caution and agreeing with Fred. Somethin' ain't adding up. Either the pushrod deflected or the flap actuator weldment deflected.
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Or the whole shebang *twisted* in such a way that one side was more extended than the other. I'd have to crawl back in to that area on my 7 to see, but if one side was jammed but the motor kept running, might it basically create a twisting/torsion action on the long, crosswise actuator bar, perhaps lifting and bending the associated bearing blocks and their attach points?

Either way...not good.

This is an excellent lesson in why FOD is such a serious thing. I never leave a tool missing after a job, and if a tool or part gets dropped, it gets found. Period.

FOD has killed people. An asymmetric flap deployment could very well have done the job.
 
RV7A Flyer said:
Or the whole shebang *twisted* in such a way that one side was more extended than the other. I'd have to crawl back in to that area on my 7 to see, but if one side was jammed but the motor kept running, might it basically create a twisting/torsion action on the long, crosswise actuator bar, perhaps lifting and bending the associated bearing blocks and their attach points?

Either way...not good.

This is an excellent lesson in why FOD is such a serious thing. I never leave a tool missing after a job, and if a tool or part gets dropped, it gets found. Period.

FOD has killed people. An asymmetric flap deployment could very well have done the job.
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The motor actuator has end limits. Once those are met, additional motor operation doesn't move the flaps any further. I think this concept is on all RV's.

There is no way that the flap torque tube (the part that goes side to side of the fuselage) could twist unless it was broken. More that likely it's a weld joint broken on the arm that is connected to the right side push rod.....
 
Fred.Stucklen said:
The motor actuator has end limits. Once those are met, additional motor operation doesn't move the flaps any further. I think this concept is on all RV's.

There is no way that the flap torque tube (the part that goes side to side of the fuselage) could twist unless it was broken. More that likely it's a weld joint broken on the arm that is connected to the right side push rod.....
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I know, but I'm talking about perhaps what would happen well before it hit the end stop. I'm just thinking out loud...if one side was essentially fixed, and the other was free, and you put a force in the middle, what would it do? I'm wondering it if would not so much twist the *rod*, but force the whole assembly, rigidly, to go cattywumpus and askew. See what I'm saying?

Basically, if one side is going down, and the other isn't for whatever reason, and the steel weldment isn't broken somewhere (and no welds gave way), the only other explanation is that the entire assembly moved and/or rotated at an odd angle.
 
RV7A Flyer said:
I know, but I'm talking about perhaps what would happen well before it hit the end stop. I'm just thinking out loud...if one side was essentially fixed, and the other was free, and you put a force in the middle, what would it do? I'm wondering it if would not so much twist the *rod*, but force the whole assembly, rigidly, to go cattywumpus and askew. See what I'm saying?

Basically, if one side is going down, and the other isn't for whatever reason, and the steel weldment isn't broken somewhere (and no welds gave way), the only other explanation is that the entire assembly moved and/or rotated at an odd angle.
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Not physically possible. The motor drives the center weldment arm that then rotates the cross weldment arm, which then moves the pushrod weldments on either side of the fuselage. The cross weldment arm is 4130 steel. No way it can twist that much unless it's broken somewhere.
 
Fred.Stucklen said:
Not physically possible. The motor drives the center weldment arm that then rotates the cross weldment arm, which then moves the pushrod weldments on either side of the fuselage. The cross weldment arm is 4130 steel. No way it can twist that much unless it's broken somewhere.
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One thing that hasn’t been mentioned is if one of the Delrin blocks that anchors the torque tube on each end came lose, the motor could push the tube “cattywampus” enough to make the flaps unsymmetrical by a little. The blocks are held by two bolts through the fuselage stringer into nutplates.
 
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Ironflight said:
One thing that hasn’t been mentioned is if one of the Delrin blocks that anchors the torque tube on each end came lose, the motor could push the tube “cattywampus” enough to make the flaps unsymmetrical by a little. The blocks are held by two bolts through the fuselage stringer into nutplates.
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Thank you Paul...that's what I have been questioning. NOT that the steel tube *itself* twists under torsion, but that the blocks and/or attach points to the floor get pulled up/pushed down on opposite sides under the force from the actuator.
 
Fred.Stucklen said:
Not physically possible. The motor drives the center weldment arm that then rotates the cross weldment arm, which then moves the pushrod weldments on either side of the fuselage. The cross weldment arm is 4130 steel. No way it can twist that much unless it's broken somewhere.
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That's not what I'm saying.

Try this thought experiment: Remove the Delrin blocks on one side, and apply a force to the middle actuation arm while "locking up" the side opposite the missing block. What would happen?
 
Ironflight said:
One thing that hasn’t been mentioned is if one of the Delrin blocks that anchors the torque tube on each end came lose, the motor could push the tube “cattywampus” enough to make the flaps unsymmetrical by a little. The blocks are held by two bolts through the fuselage stringer into nutplates.
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I replaced the regular bolts with the drilled head bolts and safety wired both of them together. It's easy to overlook these bolts
 
Ironflight said:
One thing that hasn’t been mentioned is if one of the Delrin blocks that anchors the torque tube on each end came lose, the motor could push the tube “cattywampus” enough to make the flaps unsymmetrical by a little. The blocks are held by two bolts through the fuselage stringer into nutplates.
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Cattywampus...that's one of those terms my Dad used to use! Not sure if I remember seeing it defined in my engineering textbooks from the last century, but it fits in this case. :ROFLMAO:
 
Ironflight said:
One thing that hasn’t been mentioned is if one of the Delrin blocks that anchors the torque tube on each end came lose, the motor could push the tube “cattywampus” enough to make the flaps unsymmetrical by a little. The blocks are held by two bolts through the fuselage stringer into nutplates.
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Great point! If the delrin blocks aren't secures that could result in what he is seeing....
 
Here's a picture of what is in the RV-7A plans. It's the same in both RV-6A's that I built....
1719250194204.png
Only the center Delin block uses nutplates.

1719250600764.png
 
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D-Dubya said:
Cattywampus...that's one of those terms my Dad used to use! Not sure if I remember seeing it defined in my engineering textbooks from the last century, but it fits in this case. :ROFLMAO:
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Cattywumpus was a favorite comment from the late Sheldon "Torch" Lewis. Standing on the rudder base to final would be a good use for cattywampus. Now I suppose someone will want to know about the name "Torch".
 
RV7A Flyer said:
Thank you Paul...that's what I have been questioning. NOT that the steel tube *itself* twists under torsion, but that the blocks and/or attach points to the floor get pulled up/pushed down on opposite sides under the force from the actuator.
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So what have you found???????
 
My money says the weld at the base of the left flap "arm" and torsion tube has failed...nothing "Cattywumpus" going on...

The welds at these locations are not gusseted IIRC.
 
bjdecker said:
My money says the weld at the base of the left flap "arm" and torsion tube has failed...nothing "Cattywumpus" going on...

The welds at these locations are not gusseted IIRC.
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I inspected it last night to include checking the security of the bearing blocks on the end.

There are absolutely no weld failures or cracks in any weld. The bearing blocks are solidly fixed and the former they are attached to shows no signs of bending or stress.

It is all rock solid.

Keep in mind that the right flap only deployed a couple of degrees more than the left before I retracted the flaps. It’s not like the right was at 10 degrees and the left was fixed in position.

It’s all open and I’ve got someone to add a second set of eyes to the assembly but I can’t see any hint of a failure on either side.
 
MarkCFI said:
It’s all open and I’ve got someone to add a second set of eyes to the assembly but I can’t see any hint of a failure on either side.
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Makes sense to me especially since you indicated that the difference between flaps was never extreme. Inspect carefully and move on. Might want to pull the seat pans and stick a strong magnet down between each pair of under-seat ribs to see if anything else is rolling around somewhere that might cause you a problem down the road. I did that during final assembly of both my airplanes and found something (maybe a cleko - don't exactly remember) on the second one...

Running a borescope down there is another good idea.
 
Ok, the weld failing was a bit of a stretch, but something is bent/deformed somewhere; what about the 3/8" diameter tubes? or the rod-end bearings at each end? How does the fuselage skin look - is it popped out a bit?
 
Kyle Boatright said:
Makes sense to me especially since you indicated that the difference between flaps was never extreme. Inspect carefully and move on. Might want to pull the seat pans and stick a strong magnet down between each pair of under-seat ribs to see if anything else is rolling around somewhere that might cause you a problem down the road. I did that during final assembly of both my airplanes and found something (maybe a cleko - don't exactly remember) on the second one...

Running a borescope down there is another good idea.
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I agree with Kyle. I use a SnapOn inspection scope and look into every bay and the tunnel for FOD at every CI. That’s why I don’t believe your aircraft was ever inspected. This should have been an easy find. I’ll get off the soap box now. Not sure why this pisses me off…..(not directed at you).
 
bjdecker said:
Ok, the weld failing was a bit of a stretch, but something is bent/deformed somewhere; what about the 3/8" diameter tubes? or the rod-end bearings at each end? How does the fuselage skin look - is it popped out a bit?
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Someone out there should have a flap weldment that hasn’t been installed. Easy enough to hold down one side and see how much torsional flex there is in the system. My bet is there is more than one thinks, but never had a reason to test it.
 
JonJay said:
Someone out there should have a flap weldment that hasn’t been installed. Easy enough to hold down one side and see how much torsional flex there is in the system. My bet is there is more than one thinks, but never had a reason to test it.
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Good idea :)
 
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