cnehus Posted October 13, 2018 Report Share Posted October 13, 2018 (edited) Durning this years Annual Inspection I uncovered an issue with my Throttle belcrank and rod end in the Engine Compartment. I reached behind the exhaust collector and found play in the Belcrank between the crank and rod end. A closer look uncovered the crank damaged at the rod end attach point. The rod end attach hole was elongated almost to the point of failure and the rod end was found frozen. This was a bearing type rod end vs the conical style found on current production aircraft. It is important to remember when installing the rod end to tighten the bolt enough that the rotation is via the rod end bearing NOT the bolt. If rotation is via an under torqued bolt it will result in early failure of either the crank or bolt. I elected to replace several of my older style bearing rod ends on the mixture and throttle with conical F34-14M ends from Spruce and Specility. Upon removal of the old ends inspection revieled most had some sort of looseness and or ratcheting via the bearings. I also replaced all the hardware using fiber locking casle nuts also advailable from Spruce. Should you miss a cotter pin these will not back off as they are self locking as well. YES it happens trust me! Our throttles fail to Idle if the linkage should happen to come off or fail. We have had a couple of accidents from different types of throttle linkage failures. Special attention needs to be paid to the entire Throttle and Mixtrue control system. Lots of moving parts, ware points, and direction changes within the system offer lots of points of failure. Another local aircraft has been inspected and the ends were also found to be worn. chris nehus Edited October 13, 2018 by cnehus Add photo Link to comment Share on other sites More sharing options...
George Clifton Posted October 25, 2018 Report Share Posted October 25, 2018 VERY good information!! Thanks for posting this to this forum,.. George.. Link to comment Share on other sites More sharing options...
N441V Posted June 24, 2021 Report Share Posted June 24, 2021 I had new bellcranks laser cut out of 4130 steel. I found a supplier that had the original flanged bearings and new aircraft rod end bearings. I then made new control rods from 4130 and welded in new threaded ends to accept the rod end bearings. These were made as owner produced parts. Hopefully, this will eliminate the failures that are becoming common with these controls rods and bellcranks. Ron Link to comment Share on other sites More sharing options...
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