Elevator rigging problem

B2C2 · #1 12-12-14, 01:46 PM

My 1969 T337D is in for annual. as part of that I am having them redo the rigging to deal with a problem where about 10-15 degrees of right yolk rotation was required for level flight. Flaps and ailerons are now re-rigged and correct, but my A&P is having trouble getting adequate cable tension in the elevator cables. the turnbuckles on the cables in the strut are bottomed out and the tension is 10 lbs, where manual says 20 +20-0. Has anyone seen this before and can suggest a solution? Adjustments in the flight controls area are completed and the yolks are parallel and he seems to think this area is correct. Further adjustment there will cause the yolks to not be parallel. Right now we are thinking about replacing the two cables that lead from the strut back to the elevator suspecting cable stretch, but my mechanics are suspicious that this should be required. I should mention there was a rear prop strike incident some time ago before I owned the plane that required the replacement of the boom that carries the cables, and although it is not mentioned in the log book I'm wondering if the cables may have been replaced at that time with cables of incorrect length.

hharney · #2 12-17-14, 10:23 AM

I have been in a very remote area with very limited internet and cellular services for the last week. I did reach out to a couple folks concerning your issue but have not heard anything.

Have you contacted Don Nieser? He may be a good source for options, he can be reached at 405-503-4686

B2C2 · #3 12-17-14, 03:07 PM

well it looks like the consensus is that this is due to cable stretch. I posted a support ticket on the CPA forum which Tom Carr responded to, indicating that due to the long cable runs in the Skymaster for the elevator and rudder controls, these control linkages can stretch to the point where they can't be adjusted to spec and the cables need to be replaced. Several others on the CPA site also gave the same advice. We were able today to get the tension within spec by tightening all the turnbuckles in the system. this resulted in the yolks being slightly out of parallel, but the elevator runs to the stops, with the copilots yolk bottoming at the same time, so just in spec. We will probably need to replace the cables at some point, but for this year its off the list.