hello forum,
I noticed this bump on the tail of my rv7.
What could be due?
Looks like a hard landing to me. The crease goes through the inspection plate so it can't be a manufacturing error. It could possibly have changed the incidence of the stabilizer slightly to negative thus requiring a little foreward trim in level flight.
This is quite common on RV-tailwheel using bumpy grass runways...
The cure is to rivet an angle just below the inspection plate.
I disagree that this is common. I've inspected a lot of RVs over the last 35 or so years and I find this rare. Yes, I've seen it, but not often.
Mel,
Doesn't the six have another longeron in this area and access on only one side, plus a smaller access panel as well?
Perhaps this is why the -6 is superior to the -7 ???
Mel,
Doesn't the six have another longeron in this area and access on only one side, plus a smaller access panel as well?
Perhaps this is why the -6 is superior to the -7 ???
To me it looks like a classic case of side-loading the tailwheel - it falls off the pavement and gets caught on an edge, or the two bolts that hold the socket to teh spring shear as the tail is being swung around and it falls off an edge. Either way, the tailwheel itself comes to a sudden stop while the fuselage is still trying to swing, and you put a slight kink in the fuselage structure. I've seen it on a couple airplane's, and both have had a sudden tailwheel stop event.
Just one possibility.
Paul
Any time you add an "angle" stiffener to a skin, be sure to secure it to the bulkheads at each end, either by a joggle or a shim. Without this security the skin will eventually crack at the ends of the stiffener.
On the -4 & -6, the center "J" stiffener continues all the way to the tail at the bottom of the inspection panel.
The -7 was designed after the -9. The -9 was not designed with a tailwheel version in mind.
Perhaps the designer didn't think that last bit of stiffener was needed on a tricycle. When the -7 came out, this was simply overlooked
My $.02!
Can somebody post a photo of this area or the plans of a 4 or 6?
Don
that looks like more than skin bulge to me. I would be pulling the vertical and horizontal off to check the bulkhead for damage. looks like it that could be wrinkled also.
bob burns
RV-4 N82RB
To me it looks like a classic case of side-loading the tailwheel - it falls off the pavement and gets caught on an edge, or the two bolts that hold the socket to teh spring shear as the tail is being swung around and it falls off an edge. Either way, the tailwheel itself comes to a sudden stop while the fuselage is still trying to swing, and you put a slight kink in the fuselage structure. I've seen it on a couple airplane's, and both have had a sudden tailwheel stop event.
Just one possibility.
Paul
Look at the bottom of the rudder fairing. If there is not indication of contact damage from the tail wheel, then the scenario Paul described above is likely the cause.
N477RV (the RV-7 owned by Van's and used by Mike Seager for transition training) has spent its entire life based on a grass runway airport. It is just a few hrs shy of 4800 hrs T.T. and has had nothing like this occur (not to mention all of the plopped in landings it has endured during training).
The inertia of the induced by the tail swinging can induce huge twisting loads on the tail spring mount if the tail wheel comes to a stop suddenly.
Another way to obtain the same objective would be to increase the thickness of the access cover and add several more nut plates around the opening so that the plate would become structural and carry some of the compression loads. Four screws is simply not enough to transfer the loads be across the cover panels.
Isn't a structural cover plate a contradiction in terms?Another way to obtain the same objective would be to increase the thickness of the access cover and add several more nut plates around the opening so that the plate would become structural and carry some of the compression loads. Four screws is simply not enough to transfer the loads be across the cover panels.
I have installed a beef up to the area described after talking to Scott McDaniels,
It is not a item recommended by Van's or Scott at this time.
Since the 7 fuselage is a RV9A the mid horizontal J angle was not carried through to the aft bulkhead as in the RV6, RV 8 or the RV14. I talked to Scott and he said he had seen it but not in sufficient quantity.
It took two days, did not have to remove the tail as all work was done through the aft inspection panels.
I did this as I had a extremely slight bulge and after looking at several other RV7" decided it was a nice improvement to the area. The nice part is the bulge was eliminated.
It is about 5 pages long and if you would like me to email you a copy please send me an email.
Thanks
Jack Hunt
[email protected]