[WingedFrog]

When I read the analysis of the data retrieved from the Skyview of the RV-12 that crashed in Australia, I was puzzled by the multiple trim control commands made before the brutal pitch-up. My first thought was: it's what I would try if were to lose elevator control (figure 13 of the ATSB report).
When rigging the elevator cables, we are warned to observe the number of threads left outside the turnbuckles... and for good reasons. It is possible to imagine the case where there is so little thread left that the cable could become detached under little stress.
It is unfortunate that the thread was closed before I could ask the following question:
Has anyone checked if the stabilator cables were still attached to the turnbuckles after the accident?
I don't believe the fire would have destroyed the cables so the evidence should still be there.

 

[rgmwa]

If they did, it should come out in the coroner's report. However, the pilot was also a very experienced builder and knew how to rig control cables. He had been a part of and/or closely observed all of the build of the kit, so while it can't be ruled out at this stage, it's doubtful that something didn't get bolted up correctly. Also, the trim movements were very small. Not what you would expect if the trim was being used as a primary control (even if time had allowed this to be attempted).

 

[Bill_H]

Your post title scared me half to death (!!!!) when I saw it in "new posts" and "RV12"! Yeah, any tiny change on a graph looks big when the Y-axis is waaaaaaaaaay zoomed in...

 

[WingedFrog]

Your post title scared me half to death (!!!!) when I saw it in "new posts" and "RV12"! Yeah, any tiny change on a graph looks big when the Y-axis is waaaaaaaaaay zoomed in...

The question is why would a seasoned pilot fiddle with the trim just after lift off on a first flight? As we all well know, the force required on the stick to counter bad trim is not that strong. Another observation I have is that the trim control on the RV-12 is counter intuitive, i.e., you push the trim button up for nose down and vice-versa. Here again in a critical phase, assuming loss of stabilator control, I can imagine a pilot frantically pushing the trim button down to put the nose down and ending up in a chandelle.

 

[nauga]

I can imagine a pilot frantically pushing the trim button down to put the nose down and ending up in a chandelle.

The trim in the accident in question was barely moving. The scale on the plot in the report was blown up and gives the appearance of lots of movement but when you look at the numbers it's hardly moving at all.

 

[Mich48041]

The trim switch in the RV-12 follows standard convention, pushing the top of the switch is trim down, just like pushing the top of the control stick makes the nose go down.
Perhaps the trim switch was never pushed and the small fluctuations are due to instrument or transducer error.
Joe Gores

 

[joedallas]

Trim never pushed

Ditto

I think the trim switch was never pushed.

My View

The trim switch in the RV-12 follows standard convention, pushing the top of the switch is trim down, just like pushing the top of the control stick makes the nose go down.
Perhaps the trim switch was never pushed and the small fluctuations are due to instrument or transducer error.
Joe Gores

 

[E. D. Eliot]

Lawyers

Ok, we don't know for sure what happened. Maybe we'll never find out what really happened. But, IMHO, it is unlikely that we will get more real info until the lawyers are done with it. In the US, that could take years and thousands of dollars. I feel for all involved - those who will never have peace with this incident. I hope that the builder will be able to build another aircraft and fly it - but I'd be surprised if he just didn't pack it in. I feel for him and for his family.

 

[rgmwa]

Ok, we don't know for sure what happened. Maybe we'll never find out what really happened. But, IMHO, it is unlikely that we will get more real info until the lawyers are done with it. In the US, that could take years and thousands of dollars. I feel for all involved - those who will never have peace with this incident. I hope that the builder will be able to build another aircraft and fly it - but I'd be surprised if he just didn't pack it in. I feel for him and for his family.

My thoughts too, although I'm more optimistic that we'll see a detailed report reasonably soon.

 

[gossend]

Enough already!

Now, Where do they hide that "close this thread" button?