Wednesday, September 21, 2011

Reno Crash - Further Investigation

I've received several emails and comments about the likelihood of a trim tab failure causing the recent crash at Reno. Among them was this:

"I was part of the pit crew. Jimmy was a close personal freind. I've owned Race 9 (Cloudancer) since April'10. It is common practice for air racers to zero the elevator and rudder tabs so there is less drag and less chance of setting up a buzz. I know this sounds strange, but when they are in the valley of speed it takes both hands pushing forward on the stick. And when you are turning especially pylon 7 and 8 where you need 5 to 7g's to make the corner and not bust the spectator deadline you relax the forward pressure so you dont have to pull so hard. 

If you had forward trim set in the act(tab up for down elevator) the forces on the tab would be tremendous while turning. The aircraft pitched up nearly vertical but climbed very little maybe a 100 Feet, this was accompanied by a very loud whump or a burrump sound. The aircraft slowed tremendously. Pictures show a large buckle in the right side of the fuselage, this probably tripped the tailwheel uplock cable and extended the tailwheel. The inboard 2/3's of the trimtab then seperated. Just a comment about bob hannah's tab failure, he said that when he came to he was looking at his feet"

The last comment was in reference to an incident with "Voodoo" several years ago. He lost a trim tab on the course, blacked out during a 10G pull-up and woke up to find himself at 9000 feet

And about that extended tail wheel, clearly visible in a photo shot a second or two before impact - a P-51 checklist emergency gear procedure on Aerofiles sheds some light on how extreme G-forces indeed could have extended the tail wheel:

"If there is any doubt about the tail wheel being down, dive the plane a short distance and pull out with enough acceleration to down the tail wheel."

Here's hoping for a future with the air races, but without accidents like this.

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