John Posted November 7, 2019 Report Share Posted November 7, 2019 (edited) Have seen a number of CTLS aircraft in the shop with loose stabilators. Can't emphasize enough how serious this issue is. There seems to be 2 reasons. Cracks or flexing in the structure near where the stabilator bearings mount (see pic below) and, Bad stabilator bearings due to wear and/or improper install In some cases we find both issues. I recommend that on every preflight the stabilator be wiggled up, down and side to side. If there is any detectable play, it should be addressed. First, you should install the tail beam rib available from Flight Design. I recommend installing this on any CTLS that doesn't have it at this point. If you find cracks it should be installed immediately. Newer CTLS, and all CTLSi have this factory installed. Next, if you still have play then you may also need to replace the bearings. When installing new bearings, you do need to shim properly so you don't pre-load them, or "pich" them together. When you reinstall the balance arm, there should be no side to side play before tightening the outer nuts. If so shims can be installed between the bearings, and the balance arm to fill in the gap. If you just tighten them down to close the gap the bearings will wear prematurely. These repairs should only be completed by a properly trained and rated mechanic. Finally, if you have this issue, don't forget to fill out the Service Difficulty Report http://documents.flightdesignusa.com/Service Difficulty ReportF.pdf, or Safety of Flight Report http://documents.flightdesignusa.com/safety of flight fillableF.pdf(if you notice a sloppy elevator in flight) - it is your legal obligation. Please let me know if there are any questions. Best Regards, John Edited November 20, 2019 by John grammar Quote Link to comment Share on other sites More sharing options...
Skunkworks85 Posted November 7, 2019 Report Share Posted November 7, 2019 Is this just limited to the LS? Quote Link to comment Share on other sites More sharing options...
coppercity Posted November 8, 2019 Report Share Posted November 8, 2019 Thanks for the info John. I have a late year 2009 CTLS that has always had slop in the stab due to the type of bearings it has installed, it has a spherical type bearing vs the straight type for some reason. Its the only one I've seen like it. It has a different size housing as well so the standard bearings are to small. I would have the oddball Quote Link to comment Share on other sites More sharing options...
Runtoeat Posted November 8, 2019 Report Share Posted November 8, 2019 John, is the "Tail Beam Rib" the part with the arrow going to it in your second picture? Does this require epoxying or gluing? Is there a installation drawing for this? Has a service bulletin been issued for this? Sorry for the "20 questions" but know that your the "go to guy" and for everything involving FD aircraft and thought this would help all who have older CTLS. Quote Link to comment Share on other sites More sharing options...
Anticept Posted November 9, 2019 Report Share Posted November 9, 2019 Did you remove the paint around that stabilator mounting? 99% of the time it's not structural cracking. It's just filler that's flexed and isn't something to panic about. Still, I too would suggest the brace. If it reduces flexing back there, it means less headache years down the road. Quote Link to comment Share on other sites More sharing options...
John Posted November 10, 2019 Author Report Share Posted November 10, 2019 On 11/7/2019 at 12:54 PM, Skunkworks85 said: Is this just limited to the LS? I am only aware of this happening with CTLS. Quote Link to comment Share on other sites More sharing options...
John Posted November 10, 2019 Author Report Share Posted November 10, 2019 On 11/7/2019 at 11:13 PM, coppercity said: Thanks for the info John. I have a late year 2009 CTLS that has always had slop in the stab due to the type of bearings it has installed, it has a spherical type bearing vs the straight type for some reason. Its the only one I've seen like it. It has a different size housing as well so the standard bearings are to small. I would have the oddball Eric, We recently had a plane in the shop with the spherical type bearings. They were sloppy as well. FD USA had the straight type in stock as illustrated in the MX manual. We installed the tail beam mod, and replaced the bearings with the straight type - works much better now. After removing the spherical bearings we noticed there was quite a bit of slop in them; however, they were also not installed properly and this might have led to damage. John Quote Link to comment Share on other sites More sharing options...
John Posted November 10, 2019 Author Report Share Posted November 10, 2019 On 11/8/2019 at 10:11 AM, Runtoeat said: John, is the "Tail Beam Rib" the part with the arrow going to it in your second picture? Does this require epoxying or gluing? Is there a installation drawing for this? Has a service bulletin been issued for this? Sorry for the "20 questions" but know that your the "go to guy" and for everything involving FD aircraft and thought this would help all who have older CTLS. Dick, Yes, this is the rib in the second photo with the arrow. This involves some carbon composite layups, and flux corners. No service bulletin that I am aware of. Was able to get a drawing from FD USA, would suggest contacting them for the most current drawing and install instructions. Best Regards, John Quote Link to comment Share on other sites More sharing options...
coppercity Posted November 11, 2019 Report Share Posted November 11, 2019 16 minutes ago, John said: Eric, We recently had a plane in the shop with the spherical type bearings. They were sloppy as well. FD USA had the straight type in stock as illustrated in the MX manual. We installed the tail beam mod, and replaced the bearings with the straight type - works much better now. After removing the spherical bearings we noticed there was quite a bit of slop in them; however, they were also not installed properly and this might have led to damage. John Thanks John, That is going to be my plan as well, do you happen to recall the part# for the replacement straight bearings you installed? I think there are a couple different sizes. Quote Link to comment Share on other sites More sharing options...
John Posted November 11, 2019 Author Report Share Posted November 11, 2019 On 11/9/2019 at 12:12 AM, Anticept said: Did you remove the paint around that stabilator mounting? 99% of the time it's not structural cracking. It's just filler that's flexed and isn't something to panic about. Still, I too would suggest the brace. If it reduces flexing back there, it means less headache years down the road. Corey, Actually it wasn't necessary to remove the paint in this case as you can visually see the structure flex there when you torque the stabilator up and down. Also in the pic above you might notice the crack penetrating on the aft portion where there is no paint. Best Regards, John Quote Link to comment Share on other sites More sharing options...
Anticept Posted November 12, 2019 Report Share Posted November 12, 2019 Yes, the area flexes. No contest there. Unfortunately the pictures are too low resolution for me to conclusively see cracks. I can see what could be cracks, but I also have first hand experience of being tricked many, many times by what *looked* like cracks but was dirt or the edge of a layer. Always a fun time to sand down and find out it disappears as soon as I start to remove the top layer. Quote Link to comment Share on other sites More sharing options...
John Posted November 18, 2019 Author Report Share Posted November 18, 2019 The paint crack only indicates that the area is possibly getting soft and flexing, not necessarily cracks in the carbon. Real issue is how loose the stabilator is. In this case I don’t bother removing the paint & just proceed with the repair via the tail beam mod. Quote Link to comment Share on other sites More sharing options...
Anticept Posted November 18, 2019 Report Share Posted November 18, 2019 That i will fully agree with. There's lots of places on the airplane where there is flexing going on just by nature of filler material being really bad at deformation, while composites naturally have some flexibility. There's an old post on here that I made that points out the type of cracking that you absolutely want to be on the lookout for, while others are easy to tell they're just flexing cracking in the paint and such only. Anyways that tail beam mod is absolutely a good thing and glad it exists. Quote Link to comment Share on other sites More sharing options...
okent Posted November 18, 2019 Report Share Posted November 18, 2019 Anticept, can you post a link to your old post you referenced? Quote Link to comment Share on other sites More sharing options...
Anticept Posted November 18, 2019 Report Share Posted November 18, 2019 Quote Link to comment Share on other sites More sharing options...
WmInce Posted November 18, 2019 Report Share Posted November 18, 2019 5 hours ago, okent said: Anticept, can you post a link to your old post you referenced? x2 Interested in seeing that also. Quote Link to comment Share on other sites More sharing options...
okent Posted November 18, 2019 Report Share Posted November 18, 2019 Thanks Anticept! Quote Link to comment Share on other sites More sharing options...
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