A couple of weeks ago, I attached both wings for the first time. After attaching both wings, the stick was moved left and right, no problem. Raised the flap handle to the first detent and there was some resistance. Raised the flap handle to the second detent (full flaps position) and there was a severe jamming problem. Few days later with the 12 back in the garage with the wings removed, my helper applied some lateral side pressure to the right flaperon tube (WD-1214-R) and the stick was jammed in the full flap position. Removed the gas tank and two tunnel covers. Slight lateral pressure was applied again to the right flaperon tube by my helper while I observed. The end of the AN3-10A bolt (Refer 32-06) Figure 3 (attaching the flaperon pushrod) going through WE-1215-R (right side) was hitting the the other bolt. The orginial installation of the AN3-10A bolt on the right side as pictured in Figure 3 of 32-06 was correct. Just enough lateral inward movement of the flaperon tube on the right side by attaching the wing caused the jamming. Now forward to 44-05 for those of you who have installed the auto pilot. Ref Figure 1, the AN3-10A bolt on the left side has been replaced by a longer AN3-14A bolt to facilitate the attachement of the Roll Servo Pushrod as depicted and highlighted in dark print in Figure 1. This bolt has also been reversed i.e. head of bolt is inward instead of outward. Now the cirtical point. As to the other bolt (the AN3-10A on the right side), Figure 1 (44-05) shows that bolt now reversed but in subduded print and there are no instructions as to reversing that bolt. Since that bolt was not highlighted nor were you instructed to reverse it, it did not occur to me to remove the bolt and turn it around. It also appeared there was enough clearance between the bolts but after attaching the wings, there was evidently just enough lateral inward movement of the flaperon tube to cause the interference. IMHO a very critical omission in the instructions. To those of you who have installed the auto pilot or are going to install it, make sure that bolt has been reversed to avert the possible jamming of the flaperons. By the way, N7185A, serial #120164 is now an airplane. Certification recevied yesterday. Thanks to all of the RV-12 builders who posted their comments and informationon this forum. I know that many potential building mistakes (especially by me) were averted by your postings. Your information has been greatly appreciated.
Van's Air Force
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Critical Error Found After Installing Auto Pilot
- Thread starter Boomerang
- Start date
MartySantic
Well Known Member
Does this issue exist if the AUTOPILOT and its servos are NOT installed?
Picture...
Here is the area involved. Note both bolt heads are installed inboard and will pass fairly close to each other as the flaperons are moved.
[url=http://tonytessitore.smugmug.com/RV-12-Project-N577RV/Finish-Kit/9229733_jnRJi#782487727_JdZub-A-LB]
[/URL]
Tony
Here is the area involved. Note both bolt heads are installed inboard and will pass fairly close to each other as the flaperons are moved.
[url=http://tonytessitore.smugmug.com/RV-12-Project-N577RV/Finish-Kit/9229733_jnRJi#782487727_JdZub-A-LB]
[/URL]Tony
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No it doesn't happen with no autopilot, only when you hook up the arm from the servo. He's right, it does have to be reversed and is shown that way in the plans.
Pulled the baggage compartment tunnel cover to see if my bolts were oriented correctly. They were not! The right hand bolt did not get turned around when I installed the autopilot servo. Decided to try reversing the bolt through the opening without removing the fuel tank. Was successful in doing this.
I hope Van's is tuned in to this situation. All 12's with the autopilot kit installed should be checked for this condition and corrected if necessary before further flight.
Go here http://www.mykitlog.com/users/display_log.php?user=BigJohn&project=639&category=0&log=104492&row=1 for before and after pictures of the bolts looking aft through the bulkhead opening. (I would have imbedded the picture in this post if I could figure out how!)
I hope Van's is tuned in to this situation. All 12's with the autopilot kit installed should be checked for this condition and corrected if necessary before further flight.
Go here http://www.mykitlog.com/users/display_log.php?user=BigJohn&project=639&category=0&log=104492&row=1 for before and after pictures of the bolts looking aft through the bulkhead opening. (I would have imbedded the picture in this post if I could figure out how!)
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Without stepping on any toes, I think its important that everyone remember that the written "steps" on the plans are not intended to mimic the drawings. Sometimes they do, sometimes they don't. Van's says from the beginning to read and visualize the entire section throughly before proceeding. The steps are not always complete and the drawings are not always complete. Between the two you have a completed aircraft. We are not expected to overlook any part of the instructions. If I put a bolt in backward, the I missed it, not Vans.
Peter,
Your points are well taken, but I guess I would find it easier to agree with you if the bolt to be turned around was shown in the bold part of the drawing, not in the faded out section as if it was just there for background reference but not for action.
Seems to me this is important enough to warrant a change to the instructions and a bulletin from Van's to all kit builders who have ordered the autopilot. Can you imagine the liability that Van's would incur if this caused an accident? Balance that risk out against the minimal cost of making a minor change to Page 44-05.
John
Your points are well taken, but I guess I would find it easier to agree with you if the bolt to be turned around was shown in the bold part of the drawing, not in the faded out section as if it was just there for background reference but not for action.
Seems to me this is important enough to warrant a change to the instructions and a bulletin from Van's to all kit builders who have ordered the autopilot. Can you imagine the liability that Van's would incur if this caused an accident? Balance that risk out against the minimal cost of making a minor change to Page 44-05.
John
Dgamble
Well Known Member
It would seem that for any situation bringing the potential for the binding of absolutely essential flight controls, the manufacturer of record would strive for an abundance of caution. Juries aren't exactly known for their restraint when awarding damages against manufacturers.
What's the cost of generating a Service Bulletin and page revision in comparison to the potential liability? I've seen page revisions done for far less critical items, back when I used to scan both pages in search of the often very small change.
What's the cost of generating a Service Bulletin and page revision in comparison to the potential liability? I've seen page revisions done for far less critical items, back when I used to scan both pages in search of the often very small change.
What you say is all true and after all, their name is on the dataplate. From a practical standpoint (me flying the airplane) I just don't want to be the subject of a jury trial. I will continue to look for those "faded" drawings. But yes there should be a revision I agree.
Thanks for the pictures
BigJohn,
Thanks for the link to the pictures. I am going to make sure that bolt points to the right so that, when I do install the autopilot, I will not forget to turn it around. They say that a picture is worth a thousand words, and in this case, it is true. The way to embed a picture in your posting is to click on the yellow square icon, then enter the link to where your picture is stored elsewhere on the internet. I think that Van's will eventually revise the plans to emphasize the correct bolt orientation, because they are nice people and do not want people getting killed in airplanes. Even better, Van's should call each and every purchaser of the autopilot kit before they crash and warn them to check for bolt interference.
Joe
BigJohn,
Thanks for the link to the pictures. I am going to make sure that bolt points to the right so that, when I do install the autopilot, I will not forget to turn it around. They say that a picture is worth a thousand words, and in this case, it is true. The way to embed a picture in your posting is to click on the yellow square icon, then enter the link to where your picture is stored elsewhere on the internet. I think that Van's will eventually revise the plans to emphasize the correct bolt orientation, because they are nice people and do not want people getting killed in airplanes. Even better, Van's should call each and every purchaser of the autopilot kit before they crash and warn them to check for bolt interference.
Joe
Brantel
Well Known Member
While it is great to expect Van's to revise the drawings, instructions and notify people that have this kit....
One should always perform test of the entire control system at full limits of the travel in all directions and in all combinations of angles and configurations etc. when making any modifications or additions to the control system no matter how insignificant they may seem.
Also make this part of your preflight checks to check the controls for freedom and no binding.
One should always perform test of the entire control system at full limits of the travel in all directions and in all combinations of angles and configurations etc. when making any modifications or additions to the control system no matter how insignificant they may seem.
Also make this part of your preflight checks to check the controls for freedom and no binding.
A couple of comments after doing some follow-up investigating of the possibility of this problem.
It is correct that the phantom portion of DWG 44-05 shows the bolt for the right side flaperon arm reversed from what was originally depicted on DWG 32-06. This was an oversight and is not considered to be necessary on a correctly assembled RV-12 flaperon control system.
If all parts are installed as intended, there should be a minimum of about a 3/16" clearance between the bolts when the flaperons are in the full down position. If the bolt on the right hand side is also turned around (as shown phantom in the dwg but not specified in the text), then the clearance should increase to about 1/2" (the 3/16" is considered more than adequate).
Because of lateral angle variation of the arm, because of manufacturing tolerances, these measurements could very slightly from one RV-12 to another but the variation should be small.
As designed, the clevis portion of the weldment where it attaches to its pivot bearing in the F-1206D is intended to be centered on the bearing (spaced equally on each side).
As designed, installing the wings should not put a load on the control system that would push it inboard. Any RV-12 that has this condition will likely have excess friction in the aileron circuit that will noticeably effect its flying qualities. It is likely that this lateral load on the bearing will greatly reduce the bearing's service life (this type of plain bearing doesn't like side loads).
The RV-12 Maint. Manual documents a process for contacting the manufacturer if any safety of flight issue is discovered. The LSA regulations, as adopted by the FAA, require any LSA owner to comply with this requirement.
If the RV-12 production acceptance procedure checklist is used (as required) before first flight...an extensive check of the control system is done, including putting the flap handle in all possible positions.
Scott,
Your reply leaves the question open, re: reverse the bolt or not. I reversed mine and I'm glad I did. Why not have the extra clearance regardless? I would think the engineers at Van's would feel the same way and insert a step to reverse the bolt when installing the autopilot and leave the phantom drawing as it is. Why not err on the side of safety?
John
Builders choice. As I mentioned previously, if everything is installed correctly, there should be 3/16" clearance even if you do not reverse the right hand bolt. There are numerous other places in the control system that the clearance is even tighter than this and it works fine. If a builder does choose to reverse that bolt then they should have about 1/2" clearance between the two.
A valid question I guess, but if as designed it already has more than adequate clearance, there is no need.
Personally, what would make me feel better a lot better about this situation...would be if you would analyze your control system and try and find out why it has an interference that should not be there.
You already mentioned that when you install your wings, it pushes the torque tubes inboard towards each other. It should not do this. Their position should not change. As I already mentioned, your control system is not going to be performing correctly if this problem isn't corrected and it could cause premature failure of the bearings.
Plans changed to specify bolt orientation - Good Job Van's!
Recent plans change to page 44-05 clarifies the reversal of the bolt that was causing the risk of interference. Congratulations to Van's for recognizing the wisdom of playing it safe, and taking the advice of some of us who advocated for this minor but important change.
Once again Van's has demonstrated their committment to the builders to provide the safest possible aircraft.
Recent plans change to page 44-05 clarifies the reversal of the bolt that was causing the risk of interference. Congratulations to Van's for recognizing the wisdom of playing it safe, and taking the advice of some of us who advocated for this minor but important change.
Once again Van's has demonstrated their committment to the builders to provide the safest possible aircraft.
