Bill
I believe your statement is about 90% correct.
However The kinetic energy required to stop an aircraft is a function of the weight (mass) of the aircraft multiplied by the square of its speed.
Land the aircraft faster than the design speed with loose bolts to many times by jumping on the breaks and getting tire skip things start to go wrong.
If information that I am getting from phone calls is truthful this is not from hard landings.
From talking with vans there demo aircraft has had its share of hard landings and no damage
Also we have heard that the 12 keeps flying and flying when they try to land.
This would be consistent with too fast of a landing and hard breaking.
( Pilot Error ) ( Learn your aircraft )
My view
Joe, though not an official notification, this is pretty much my view also (as an explanation for the cracked C channels anyway).
As a (personal opinion) response to some of the comments that have been bouncing around the forum......
The ASTM's that the airplane was certificated under, have a huge # of tests that need to be complied with. Quite a few of them are related to the landing gear. Most of those are physical drop tests where a fuselage is loaded to a specific weight and dropped from specific heights in a variety of conditions meant to simulate hard touch downs at high alpha angle of attack, very flat (improper) touch downs (all three wheels at once), and even a test for nose wheel first (very improper touch down).
One of the gear tests is an aft pull load applied to the main gear legs. This is to simulate the potential load caused by heavy braking at gross weight, with the maximum friction coefficient that could ever be expected between the tires and the ground. An additional amount of load is designed into this test for a design safety factor just as is done for wing tests, etc.
I do not believe that the speed which brakes are applied, has a major effect on what load the gear leg feels. The load will peak at the moment that the tire is just about to begin to skid/slide. This load point will always be relatively constant regardless of speed. It is primarily, only effected by variables of brake pad/disk condition, tire condition and traction/grip rating, surface condition (pavement/grass, dry/wet, etc.), and to some degree, the airplanes weight. In theory, it could be argued that a higher load could be induced at a slightly lower speed, because the higher the speed, the more lift that is being produced by the wing (even once rolling on the wheels), thus reducing the amount of weight that is actually induced into the contact footprint between the tire and ground. Less weight on the tire will lower the possible load before the tire begins to skid/slide.
The RV-12 test fuselage passed all of the tests (BTW, technically a new fuselage could be used for each test, but in the RV-12's case, the same one was used for every test).
An RV-12, if built as designed, and flown properly, within the design gross weight, should perform the same way that the drop test fuselage did.
So, why have some airplanes gotten damaged? That is still not fully clear at this point. As of early this week, only 3 reports had come in to Van's. I believe more have come in during the week, but not as many as would be expected considering the # that Don has reported receiving information about. As Mike S. already mentioned, is the unwillingness for people to notify Van's an indicator of what caused their damage? We will probably never know.
Summery....
I think damage to the channel has been caused by excessively loose gear legs. At least one of the photos posted here by Don (as far as I know, it has never been sent to Van's by the airplanes owner) looks to have evidence of plastic deformation in the surface of the channel from the washer pounding into the surface (I,E, there appears to be a depression slightly bigger than the diam. of the washer, actually pounded into the surface of the channel).
Another owner here on the forum was recently petitioning for help in solving a nose wheel shimmy problem. From the description he gave, I posted that it didn't sound like nose wheel shimmy was a likely cause. A little while later he posted in this thread that he found the outboard bolts for his main gear legs loose. He has never stated so, but it is my guess that the loose bolts were the cause of what he thought was nose wheel shimmy.
Considering the tests that the design originally passed, and the operational experience that exists within the fleet, I don't feel that RV-12 owners need to be worried about going easy on their brakes. Particularly on grass runways (pavement should always induce the highest loads). Builders do need to be sure their legs are tight (there will likely be recommendations issued regarding this).
Finally... It is my opinion that the damage to side skins is a different issue, and not directly related to loose gear legs and/or damage to the channel. I believe it is pure overload from a very hard landing (possible even with some level of brake application at touchdown).
It is always possible that some owners have experienced a very hard landing, with loose gear legs, so that the overall problem would be amplified, but I think they are two individual issues, that in a few cases might at first look like the are linked, but are probably not. I don't think enough evidence has come into Van's to in any way substantiate they are directly related.
This issue is also being looked at, though it would be helpful if the owners that have experienced damage to side skins, would submit reports that included a download from their D-180.