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9A flap failure

R

Rocky

I'm New Here
This morning I landed with my right flap (electric) hanging down at a 90 degree angle. A quick look indicated the rod leading into the flap had broken just outside the plastic roller - where it enters into the flap. I know this is scanty information but untill I get home tonight and look into it further this is all I know. Has this happened to anyone else? Any suggestions?
Thanks, Rocky
 
Rocky,

Thanks and welcome to the forum.

Are you saying the aluminum hexagon flap rod, between the two rod end bearings broke, or the powder coated steel arm that is welded to the flap torque tube broke?

Good to hear you landed safe and sound, regardless.

Any idea how many hours and landings on your plane?
 
Thanks. From the drawings it looks to be (and I am taking a chance here) the hexagon rod, F-659. I will get a better look tonight. No idea on the landings. About 280 hrs. I just bought the A/C last week.
 
Thanks for the info. You confused me with your "had broken just outside the plastic roller" comment. I don't recall a "plastic roller" anywhere around the flap connection, other than the bearing blocks that hold the torque tube in place.

And welcome to the wonderful world of Van?s aircraft. Congratulations on your purchase.
 
All right. Lets start over. After a a daylight examination and talking with Van's technical support, I have a much clearer picture of what happened.
There is no broken rod. The bolt leading into the flap became unscrewed. While I don't know why this happened, a contributing factor was probably the 3/8-1/4" washer that I mistook for a plastic wheel. Van's technician told me there should be 2 small washers, one of which is a locking washer, on the bolt. I had the appropriate locking washer but the second washer was that large washer. Our guess is that prohibited turning the bolt to the proper depth insertion into the flap. Checking the other (left side) flap showed it had the correct washers. Sorry for the misinformation and thank you for your response.
 
Care to elaborate on the landing itself? Were you able to see the position of the flap while in flight? I'm curious if the flap was pushed up or if it was really hanging down on final. What were the handling characteristics? Did you leave the left flap down?

Can't say that I've ever heard of this before. I do check the flap rod during pre-flight by grabbing and twisting it to make sure it rotates slightly to make sure it isn't binding and I also usually grab the flap and wiggle it up down.

Glad things turned out well...

Matthew

Rocky said:
This morning I landed with my right flap (electric) hanging down at a 90 degree angle. A quick look indicated the rod leading into the flap had broken just outside the plastic roller - where it enters into the flap. I know this is scanty information but untill I get home tonight and look into it further this is all I know. Has this happened to anyone else? Any suggestions?
Thanks, Rocky
Click to expand...
 
Rocky said:
All right. Lets start over. After a a daylight examination and talking with Van's technical support, I have a much clearer picture of what happened.
There is no broken rod. The bolt leading into the flap became unscrewed. While I don't know why this happened, a contributing factor was probably the 3/8-1/4" washer that I mistook for a plastic wheel. Van's technician told me there should be 2 small washers, one of which is a locking washer, on the bolt. I had the appropriate locking washer but the second washer was that large washer. Our guess is that prohibited turning the bolt to the proper depth insertion into the flap. Checking the other (left side) flap showed it had the correct washers. Sorry for the misinformation and thank you for your response.
Click to expand...

I think I'll put mine together with some locktite
 
Drawings for the 9A

I just installed and adjusted the flap p-rod on the right wing this week. Vans 'structions say to use a thin (L) washer, an internal tooth lock washer, and Loctite where the lower rod end bearing screws into the flap.
 
I don't know when the flap dropped. I did not see the flap malfunction until I landed.
I began to feel uneasy shortly after lift off, at about 300' and the airpeed indicating about 90KTS. I quicky decided to do a RTLS and dropped the flap(s). In retrospect, I believe the airspeed stopped the flap from fully descending. If the wind had not kept the flap from fully deploying, I am not sure I could have recoverd from that altitude. By the time the air speed dropped, the other flap was deployed.
The feeling was similar to a strong crosswind that I responded to with a wing low approach.
I don't know that a more through pre-flight would have revealled the potential problem, but it couldn't have hurt. It will certainly get my attention from now on.
 
Smart Move Rocky

Rocky said:
I don't know when the flap dropped. I did not see the flap malfunction until I landed.
I began to feel uneasy shortly after lift off, at about 300' and the airpeed indicating about 90KTS. I quicky decided to do a RTLS and dropped the flap(s). In retrospect, I believe the airspeed stopped the flap from fully descending. If the wind had not kept the flap from fully deploying, I am not sure I could have recoverd from that altitude. By the time the air speed dropped, the other flap was deployed.
The feeling was similar to a strong crosswind that I responded to with a wing low approach.
I don't know that a more through pre-flight would have revealled the potential problem, but it couldn't have hurt. It will certainly get my attention from now on.
Click to expand...

Sounds like your good judgment and quick thinking kept a bad situation from getting any worse. Good job and glad your safe.
 
Free floating flap

Sounds like flap was just free floating, so would have just created drag from deflection based on it's weight against the airflow.... thus the 'cross wind sense'. Lucky it didn't get jambed in some way once the hex rod came loose!
 
asymmetric flap is a very dangerous situation, sounds like you got really lucky in that the flap floated not totally out of normal range!!!

that's why almost all smaller (and even bigger) aircraft have mechanical flap linkages. the pc-12, while very soundly engineered, has independent flap drives and had some asymmetric flap accidents before the system was improved.

to confirm again, it was not actually the hex rod failing but simply the bottom eyebolt unscrewing from the flap?

rgds
bernie
 
I think that the loose flap was not the problem.

I was the other flap down and working would cause more lift and drag on that side. Of course of the flap had jammed in a strange position that would have been even more of a problem.

Kent
 
Rocky.... I personally appreciate the posting. Issues that other RV'ators have can only make us safer as a group! I bet more than a couple of us will be paying a lot closer attention during annual inspections and pre-flights! Hopefully this doesn't taint your RV-9A experience.. they are fabulous machines!!

As a small testament to the RV-9A's capability (and I'm sure someone can attest to this as well) I managed a very nice landing yesterday with a 25kt Gusting to 31 direct crosswind.. and I do mean direct. I wouldn't normally be up flying in that kinda of wind but when we departed it wasn't all the bad.


Rocky said:
I don't know when the flap dropped. I did not see the flap malfunction until I landed.
I began to feel uneasy shortly after lift off, at about 300' and the airpeed indicating about 90KTS. I quicky decided to do a RTLS and dropped the flap(s). In retrospect, I believe the airspeed stopped the flap from fully descending. If the wind had not kept the flap from fully deploying, I am not sure I could have recoverd from that altitude. By the time the air speed dropped, the other flap was deployed.
The feeling was similar to a strong crosswind that I responded to with a wing low approach.
I don't know that a more through pre-flight would have revealled the potential problem, but it couldn't have hurt. It will certainly get my attention from now on.
Click to expand...
 
Rocky said:
All right. Lets start over. After a a daylight examination and talking with Van's technical support, I have a much clearer picture of what happened.
There is no broken rod. The bolt leading into the flap became unscrewed.
Click to expand...
Hi Rocky - thanks so much for posting this. It helps us builders a lot. My plans look like this


When you say the "bolt unscrewed" I think you really mean the rod end bearing backed out of the flap, not out of the hexagonal pushrod? In other words, the part that is shown in the drawing end-on (into your monitor) not the part pointed up?

This is a weird rod end bearing because it has a stud in the bearing part not a hole.

Is there any way to put some orange "torque seal" on the stud part where it threads into the flap so you can see it during preflight? Of course loctite and the proper hardware per plans is needed too.
 
Flap detached

Sounds like the air loads kept it tight against the rod until you slowed down and then it simply dropped down 90 degrees and swung lazily on the hinges. Good idea for all of us to make sure it is secured in some way prior to flight (loctite / jam nut with "witness mark", etc.).

Doug Lomheim
90116 FWF, etc. (finish this year?)
 
Thank you for your comments. I replaced the large washer/spacer with the correct washer (yes, it is the rod end going into the flap vice into the a/c). I also notices the rod end bearing didn't seem as free as it the L one and replaced It as well. I don't know what, if any, impact this may have had on the malfunction. BTW, the technical advisors at Vans were great! Now attacking missing screws, and L tank end plate gas leak. Looking forward to flying.
 
Rocky said:
Thank you for your comments. I replaced the large washer/spacer with the correct washer (yes, it is the rod end going into the flap vice into the a/c). I also notices the rod end bearing didn't seem as free as it the L one and replaced It as well. I don't know what, if any, impact this may have had on the malfunction. BTW, the technical advisors at Vans were great! Now attacking missing screws, and L tank end plate gas leak. Looking forward to flying.
Click to expand...

Great! If you just purchased this plane and you haven't yet had a builder give it an inspection, you might want to. A builder might catch other problems that were missed by an A&P inspection.

Welcome to the gang!
 
flap failure

Hi Rocky,
I too am in the 'just bought it' phase.

I've been around aircraft a bit, so every walk-around/pre-flight is more like a 50-hour inspection!
where I think i am weak on airframe and systems knowledge, I contact the builder, and/or pull out the plans to try to fill in the void....otherwise, this or that bolt looks just fine without me really knowing what it does or how it should appear.

Best of luck with your repair, and kudos for the excellent piloting you exhibited.
 
Does anyone know if Van's (or any other manufacturer) test fly each model and deploy a single flap little by little to see if the aileron can overcome it and still maintain control in roll ?

I know I've taken my RV-4 up high and slow, then moved the pitch trim all the way fore and aft, just to see how much stick force in pitch there is.

After finding out it was still controllable in most all speed ranges (fast and slow) I decided I could live with a pitch trim servo run-away in flight and simply land to fix it.

Not sure about a single flap though..:eek:
 
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