dbahn
Pattern Altitude
The day before yesterday after 25 glider tows in the Pawnee, we paused for showers moving our way that I could see on the previous tow. Radar was showing a fairly rapid buildup so we scrambled to get five gliders into their hangars or secure tie-downs. I taxied to the Pawnee to its hangar and used the winch to pull the plane into the hangar (we use a rope on the tow hitch for the winch). All of the flights that day were normal with nothing unusual with the Pawnee.
Yesterday as I was pre-flighting the plane in the hangar I noticed a bend on the inside surface of the left elevator and a slight waviness in the fabric.
Thinking that maybe I had somehow missed this on dozens of previous days of towing, I compared it to the same tubular area on the right elevator:
There clearly was a difference and it was a new finding. I wondered how that could possibly have happened since I was the only one flying it that day, it flew perfectly normally and I personally handled the taxiing back to the hangar and getting it into its usual spot. What was then even more surprising was when I stood back and looked at both elevators simultaneously and saw this:
The entire elevator assembly had somehow been twisted with respect to each side, with no apparent cause. There was speculation that somehow it might have been hit by one of the golf carts used to tow gliders in the scramble to put things away, but that seems extremely unlikely to me as someone in the dozen or more people would have seen it and have said something. Plus there was no evidence of any kind of impact anywhere on the elevator. The mechanic who came to remove it yesterday thought that it might have been some kind of internal failure caused by internal corrosion.
Comfortable knowing that I had noticed it on a pre-flight, I still wondered what would have happened had it been flown in that condition. Obviously there would have been right rolling force applied to the fuselage, but how bad? Would there be enough aileron authority to keep it level? How bad would the added drag have been? Would there be sufficient excursion of the twisted unit to control pitch during take-off and landing?
To get some idea of the amount of torsional deformity, I had the mechanic hold the right elevator parallel to the horizontal stabilizer and I took this picture from the left side. Pretty scary situation. Has anyone ever seen something like this??
.
Yesterday as I was pre-flighting the plane in the hangar I noticed a bend on the inside surface of the left elevator and a slight waviness in the fabric.
Thinking that maybe I had somehow missed this on dozens of previous days of towing, I compared it to the same tubular area on the right elevator:
There clearly was a difference and it was a new finding. I wondered how that could possibly have happened since I was the only one flying it that day, it flew perfectly normally and I personally handled the taxiing back to the hangar and getting it into its usual spot. What was then even more surprising was when I stood back and looked at both elevators simultaneously and saw this:
The entire elevator assembly had somehow been twisted with respect to each side, with no apparent cause. There was speculation that somehow it might have been hit by one of the golf carts used to tow gliders in the scramble to put things away, but that seems extremely unlikely to me as someone in the dozen or more people would have seen it and have said something. Plus there was no evidence of any kind of impact anywhere on the elevator. The mechanic who came to remove it yesterday thought that it might have been some kind of internal failure caused by internal corrosion.
Comfortable knowing that I had noticed it on a pre-flight, I still wondered what would have happened had it been flown in that condition. Obviously there would have been right rolling force applied to the fuselage, but how bad? Would there be enough aileron authority to keep it level? How bad would the added drag have been? Would there be sufficient excursion of the twisted unit to control pitch during take-off and landing?
To get some idea of the amount of torsional deformity, I had the mechanic hold the right elevator parallel to the horizontal stabilizer and I took this picture from the left side. Pretty scary situation. Has anyone ever seen something like this??
.
Last edited:
