The Great Planes 70” Waco was reduced to this pile of hardware due to a failure to properly preflight the aircraft. The underlying physical issue was insufficient up elevator travel to pull out of the dive.
Down in the corn (big thanks to Bob who ventured in with me) we wandered around finding nothing. My brain kicked in…hey, I can use the RSSI indicator on my TX. I called Dan M who brought it to me on Amrein Rd. From there I followed the increasing signal strength meter and would stop every 20ft or so and scan the radio back and forth like a metal detector. Find the signal high point and then walk some more. It took me straight to it in no time at all. Note to self: use the radio. Note to self: don’t crash in the corn!
Swiss Cheese: lining up the holes
(Hole 1) I had two failed takeoffs with the 70” Beech Staggerwing due to a free floating tailwheel and I was impatient in getting my first flight in for the day. (The Beech rudder is too small to counteract p-factor until it has sufficient speed.)
(Hole 2) My Frsky TX has an ability to auto-trim every surface with the touch of a single button. The plan was to use this feature on the maiden flight and then disable the button but I never did. For years I flew this way. And yes, I have bumped the magic trim button accidentally on various aircraft. (( It saves these settings directly to the Sub Trim, which is important because visual trim settings on the TX display screen get zeroed out. You are resetting center.))
(Hole 3) I successfully flew the Waco three weeks prior and trimmed it with the normal trim controls (not auto-trim) and it needed a LOT of up elevator. Almost max trim to get it level. I had apparently bumped the magic trim button in a nose down attitude and I failed to investigate that after the flight.
(Hole 4) The visual trim indicators on my transmitter display are on the second page, so I never saw the up trim settings during preflight. I would have seen the dramatic up trim.
(Hole 5) During the control surface travel check, my brain acknowledged that the up elevator throw seemed less than usual. But quickly dismissed it with “I can use med, or hi, rates if need be.” Impatience.
(Hole 6) Prior to the previous successful flight, I tried to program Flight Modes on my TX. I was unsuccessful so I backed those changes out. Whatever I did messed up my Rates and during that previous flight I noticed high/medium rates switches were not working. Rates were not changing. So I had no med/hi elevator rates available. Again a failure to investigate that after.
Six Holes = Swiss Cheese
Prior to the crash, I noticed sluggishness and during a base leg turn realized I was pulling full up elevator just to maintain the turn. I quickly thought LAND but NO…I went with “climb and check it out.”
I flipped the Rate switch to medium and passed the center line before banking 45 degrees away from me. Went to turn downwind and it headed downhill. I switched to High rate…nothing. I had no travel to work with. I retard the throttle and then popped in an attempt it to blow more air over the elevator. It did shallow the dive a bit but the corn was quicker.
So, due to an apparently large nose down Sub Trim and the drastic nose up Trim…I was left with insufficient Up Elevator travel to pull out of the dive.
Lessons learned
- Technology can bite you in the arse.
- Slow down and do it right.
- Ensure surfaces are not only moving in the right direction but also correct length of travel.
- Don’t override or ignore anomalies.
- I am sure there are more…
