Hello,
I recently purchased a 20 year old smith cub with overhead trim (not sure when or if cable was replaced--the plane received new fuselage fabric in 2020). I experienced intermittent difficulty actuating the trim in flight. I assumed the jackscrew to be improperly lubed or worse. I cleaned and lubed and was working the trim stop to stop. Same difficulties and I found 3 sections of the cable to be frayed quite severely all within 3 feet of each other. When one of the frays when through the lower aft pulley it eventually knocked the upper loop off the pulley.
I cut out the cable and measured end to end. It is 362". The stock Piper cable is 360".
My assumption is that I will need to custom order a 362" cable, but I'm curious if any overhead trim guys have data on what length they use for the continuous loop. I'm not sure if all smith trim systems are welded in the same place or follow the same travel. I also assume these cables don't have stretch or nearly 2" worth to make the stock cable work?...The aft spring pulley looks new and has solid tension.
Besides replacing the cable, I'll also inspect each pulley for burrs and the routing. I don't know how the cable would fray in multiple sections without an obvious defect somewhere.
Is McFarlane the best source for custom spliced continuous loops or other vendors available? Thanks for any insight!
I recently purchased a 20 year old smith cub with overhead trim (not sure when or if cable was replaced--the plane received new fuselage fabric in 2020). I experienced intermittent difficulty actuating the trim in flight. I assumed the jackscrew to be improperly lubed or worse. I cleaned and lubed and was working the trim stop to stop. Same difficulties and I found 3 sections of the cable to be frayed quite severely all within 3 feet of each other. When one of the frays when through the lower aft pulley it eventually knocked the upper loop off the pulley.
I cut out the cable and measured end to end. It is 362". The stock Piper cable is 360".
My assumption is that I will need to custom order a 362" cable, but I'm curious if any overhead trim guys have data on what length they use for the continuous loop. I'm not sure if all smith trim systems are welded in the same place or follow the same travel. I also assume these cables don't have stretch or nearly 2" worth to make the stock cable work?...The aft spring pulley looks new and has solid tension.
Besides replacing the cable, I'll also inspect each pulley for burrs and the routing. I don't know how the cable would fray in multiple sections without an obvious defect somewhere.
Is McFarlane the best source for custom spliced continuous loops or other vendors available? Thanks for any insight!
