Thanks for posting Stan.
Were these cracks visible from the exterior?
JUst about ready to accomplish this task this weekend. I was told that Van's posted the dimensions for the plywood to go inside the tail cone. Where would I find this information?
Does anyone have dimensions for doubler plate if cracks are found? I'd like to pre-make some plates. Need thickness as well. Thanks in advance...
Does anyone have dimensions for doubler plate if cracks are found? I'd like to pre-make some plates. Need thickness as well. Thanks in advance...
I have been installing SBs for 10 years now. I would say over 3/4 of them are fixing problems I don’t have when my airframe time is well above the aircraft that caused Vans to issue the SB.
Very much appreciate Vans and others finding the more vulnerable places on the aircraft that I may have overlooked...and then I can decide which ones need to be proactively addressed or just monitored. We signed up for this adventure when we decided to build, did we not?
Unless a universal design or material/fabrication issue exists it seems gathering field inspection results would be useful in the decision process to issue a new SB.
The word has gotten out with one of our local RV-12 owners booking in one of our students to do the SB on his own aircraft
i have some fiberglass cloth that is made in a roll like tapes for covering cloth planes. maybe 11/4'' wide. i am thinking of covering a piece laid out flat on the bench with epoxy. after it cures i would glue it to the inside belly using proseal, having made it so it would fit over the flange of the bulkhead attached to the belly. run it for and aft, left and right of the center seam. after the proseal had set i would put a piece of 3/8'' rope down the length of the fiberglass cloth, cover it with cloth and epoxy making a more or less rigid strip. the object of all this would be to eliminate oil canning.
yes, maybe the sb is all that will be needed, maybe it won't .but i think there is a lot of flexing of the belly skin going on back there.
anybody thought of something like this? i am sure this basic idea could be refined and improved. any thoughts?
Just completed SB-00053 this afternoon. Took about 3 hours total (removing seats, opening bulkhead, cleaning up after). Now, this is my first time completing a service bulletin and I'm wondering how to write this up in the airframe log book.
I did the SB yesterday - 120 hours TT and found the same cracks at F1208 and fitted a repair patch.
Completed Service Bulletin 00053 without much weeping or gnashing of teeth. Many thanks to all who made this easier by sharing their experience in detail. Would have been more painful without the benefit of the trail blazers.
89.0 hours TT and fortunately no cracks observed at any bulkhead. No patch/plate installed; just the stiffening brackets.
Were the cracks you observed inside only?
We are starting to get serious about SB00053. Tonight, we took photos of the bulkheads using a cellphone taped to a long extension pole. Worked great. Cellphone was set to record video with the flash set to “on” for constant illumination. Video was “AirDropped” to MacBook and screen shots taken to view each bulkhead. Really worked a charm…
We have three RV-12’s that need this SB completed and this is the first airplane in line. Hours are ~ 300 TT. It appears that the only crack found is on the front side of the first bulkhead directly behind the baggage compartment.
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I trimmed the patch to size and match drilled the three holes to the forward clip in the shop. I then clecoed the patch to the skin using those three predrilled holes and match drilled the remainder of the holes to the skin from inside the talecone.
Not a difficult project.
I'm curious why there seems to be no apparent connection between time in service, runway surfaces used and the presence of cracks. I can only assume the degree of edge preparation/smoothness of the J-stiffener is a contributing factor. My plane has done 225 hours, mostly off bitumen surfaces, but also quite a few landings and take-offs on grass and gravel.
I agree with your speculation. Some aircraft seem to have cracks every time a SB is issued to look for them. Others, never. Some builders are obsessive in deburring, filing, sanding etc... every single edge. (personally, I call that good craftsmanship) Others, not so much.
Flight Youth Engineering students completed 2 x SB00053 in the last month.
The first was on the non-attached tail cone and with the help of some tall young students!
The tail cone was lowered vertically over one of our students where standing on a chair it was a breeze to access the rear bulkhead.
Hi all,
I have to add a doubler plate at the forward bulkhead since I found a crack on the forward side.
Is anyone using sealant under exterior doubler plates- if so, what specifically? or just clean everything up, paint the plates and rivet them in place per the SB?
The SB doesn't call for any, but as I read it, AC43.13-1B page 6-133(c) defines the need for sealing exterior doubler plates as a defense against further corrosion.