Guitarmaster Posted March 7, 2016 Report Posted March 7, 2016 Hi all. Just wanted to pass this on.... I have had a problem with the trim sticking at high speed. There was another poster somewhere with the same problem. This is what I have found... The jackscrew is completely free with old grease cleaned out and new applied. Still had the problem. All u-joints are free. Still had the problem. I took the cover off the trim wheel and found what looked like a nicely lubed chain. Not so. The chain was almost completely solid with old, sticky grease! I am in the process of cleaning and re-lubing the chain and sprockets now. I will let everyone know if it solves the problem... The landing gear actuator seems to be suffering with the same problem. That will also be disassembled, cleaned and greased. I LOVE annual time........ I hope my posts may help someone in the future! 3
Cody Stallings Posted March 9, 2016 Report Posted March 9, 2016 I had that same problem Matt. When that chain brakes at full nose down trim @ 9K, it feels like you have a Chevy 454 under the hood when you get in the pattern to land. When you lower the 3 wheeler to land, feels like there are 2 Chevy 454's under the hood...... Two hands worth of back presure. After looking at the chain laying next to the new one from Maxwells, the links were heavily stretched. New chain installed, works like a top. 1
MyNameIsNobody Posted March 9, 2016 Report Posted March 9, 2016 7 hours ago, Cody Stallings said: I had that same problem Matt. When that chain brakes at full nose down trim @ 9K, it feels like you have a Chevy 454 under the hood when you get in the pattern to land. When you lower the 3 wheeler to land, feels like there are 2 Chevy 454's under the hood...... Two hands worth of back presure. After looking at the chain laying next to the new one from Maxwells, the links were heavily stretched. New chain installed, works like a top. I applied a 429 Cobra-Jet and still came up with two hands worth of back pressure...
Gary0747 Posted March 9, 2016 Report Posted March 9, 2016 So is replacing the chain good PM? What size and where do you get one? 1
carusoam Posted March 10, 2016 Report Posted March 10, 2016 Stretched chain may be related to operations with old hardened grease. Typical challenge before information was readily available and spread like at MS. If you haven't seen this chain before, it would be good to get a look at it. A good part of it should be visible while you are on the ground. If you are not familiar with hardened grease, search hardened grease on the trim Jack screw for additional information. My C did not ever experience a broken trim chain, but it did come with years of solidified grease. Best regards, -a-
Cody Stallings Posted March 10, 2016 Report Posted March 10, 2016 Not real sure the chain size, I just called Maxwell's $65 later it was done.
aviatoreb Posted March 10, 2016 Report Posted March 10, 2016 Wow - that's scary a broken trim chain in flight. I have broken a number chains over the years - on my bicycles. There is a stretch test tool that measures how much they have stretched so you can pre-emptively replace before it breaks. There must exist such a thing for our airplanes.
Yetti Posted March 11, 2016 Report Posted March 11, 2016 From memory I would think it is #25 chain. http://www.mcmaster.com/#roller-chain/=11hiu5h Bike chains don't "stretch" they wear on the roller pins and then the go no guage will fit into the excess slack that has been created by wear. I would doubt that rolling the trim wheel up and down would create enough wear to show. 1
Gary0747 Posted March 11, 2016 Report Posted March 11, 2016 I agree with Yetti. It is hard to see a chain in this service wear out. I would think breaking by exceeding the tensil strength of only 80 pounds or having a connector link come loose would be the more likely cause. Do any of you who had a chain failure know the cause?
N201MKTurbo Posted March 11, 2016 Report Posted March 11, 2016 I would take the whole trim wheel assembly out, take it all apart, clean all the old grease out, inspect the gears, re-lube and re-shim it, clean the chain. Then you can run it on the bench and see if it is working OK. It is not that hard and it will be good for another 40 years.
aviatoreb Posted March 11, 2016 Report Posted March 11, 2016 1 hour ago, N201MKTurbo said: It is not that hard and it will be good for another 40 years. Unless reassembled incorrectly. I agree it would be good - but to be sure a mooney specific knowledgable shop does the work.
Guitarmaster Posted March 15, 2016 Author Report Posted March 15, 2016 We tracked the problem to down to, believe it or not, the indicator. There is a a little block of aluminum that rides on a jackscrew (not the one in the tail) that has a cable attached to it. The both the block (trim stop) and the cable to the indicator were sticking. After cleaning and lubing, the trim runs smoothly now. Flight testing is next, but I am reasonably sure that was the problem as I can roll the trim through full travel with no binding.
carusoam Posted March 15, 2016 Report Posted March 15, 2016 Hmmmm... The sensor/monitor effects the system that it is monitoring...(that can't be good) Anyone remember Schrödinger's cat in the trunk discussion? Best regards, -a-
N201MKTurbo Posted March 15, 2016 Report Posted March 15, 2016 Was it the cable or the screw and block that was sticking?
Hank Posted March 15, 2016 Report Posted March 15, 2016 4 hours ago, carusoam said: Hmmmm... The sensor/monitor effects the system that it is monitoring...(that can't be good) Anyone remember Schrödinger's cat in the trunk discussion? Best regards, -a- It's the Heisenberg Uncertainty Principal, writ large! Determining the location of an object can effect the objects location. This normally has little effect on "normal" matter, but as size of the object shrinks, it comes into play. I remember it being a big deal with electrons, to say nothing of quantum mechanics. Besides, Schrodinger's cat will die sooner or later, just lock the trunk for a couple of weeks and give a sniff to confirm, without opening the trunk. 1
mooniac15u Posted March 15, 2016 Report Posted March 15, 2016 The Uncertainty Principle really deals with the precision with which you can measure pairs of parameters, most often position and momentum. Precise measurement of position precludes precise knowledge of momentum. It isn't a statement of direct influence of the observer on a single measurement. I think Observer Effect is what you are describing here. https://en.m.wikipedia.org/wiki/Observer_effect_(physics) 1
Guitarmaster Posted March 16, 2016 Author Report Posted March 16, 2016 13 hours ago, N201MKTurbo said: Was it the cable or the screw and block that was sticking? Yes. The cable was stiff and would bind, but also the aluminum block would as well. There was hard sticky grease on the sides of the channel it runs in. There was some gunk on the jack screw that was catching in the threads too.
carusoam Posted March 16, 2016 Report Posted March 16, 2016 Great photo explanation! Thanks for sharing those. Best regards, -a- 1
Shadrach Posted March 16, 2016 Report Posted March 16, 2016 1 hour ago, Guitarmaster said: Yes. The cable was stiff and would bind, but also the aluminum block would as well. There was hard sticky grease on the sides of the channel it runs in. There was some gunk on the jack screw that was catching in the threads too. I have come to the conclusion that there are multiple points in the system that cause the high speed stiction. I have yet to find ours. The indicator block on my bird has been thouroughly cleaned and lubed yet the high seed stiffness continues. 1
Guitarmaster Posted March 16, 2016 Author Report Posted March 16, 2016 1 hour ago, Guitarmaster said: Yes. The cable was stiff and would bind, but also the aluminum block would as well. There was hard sticky grease on the sides of the channel it runs in. There was some gunk on the jack screw that was catching in the threads too. I have come to the conclusion that there are multiple points in the system that cause the high speed stiction. I have yet to find ours. The indicator block on my bird has been thouroughly cleaned and lubed yet the high seed stiffness continues. Most of the systems on the Mooney I find quite ingenious. This is not one of them. Sent from my XT1254 using Tapatalk
N201MKTurbo Posted March 16, 2016 Report Posted March 16, 2016 I know you said that you cleaned the jack screw in the tail, but did you remove it from the plane and take it completely apart? It sounds like that is where your problem is at. The trim wheel assembly is not affected by airspeed where the load on the jackscrew is highly affected by airspeed. I have written before about how to remove the jackscrew and rebuild it. If done correctly it is an afternoon project. 3
Shadrach Posted March 16, 2016 Report Posted March 16, 2016 7 minutes ago, N201MKTurbo said: I know you said that you cleaned the jack screw in the tail, but did you remove it from the plane and take it completely apart? It sounds like that is where your problem is at. The trim wheel assembly is not affected by airspeed where the load on the jackscrew is highly affected by airspeed. I have written before about how to remove the jackscrew and rebuild it. If done correctly it is an afternoon project. I've not done that yet. Is there a procedure outlined in the MM?
N201MKTurbo Posted March 17, 2016 Report Posted March 17, 2016 2 hours ago, Shadrach said: I've not done that yet. Is there a procedure outlined in the MM? http://mooneyspace.com/topic/2015-trim-wheel-very-hard-to-turn/?do=findComment&comment=21934 http://mooneyspace.com/topic/16503-trim-sticking/?do=findComment&comment=233888 2
Guitarmaster Posted March 17, 2016 Author Report Posted March 17, 2016 Yes, removed, cleaned and relubed. Very smooth operation now. Not much to it, two sealed bearings and a jackscrew. Sent from my XT1254 using Tapatalk
Recommended Posts