0TreeLemur Posted January 3, 2019 Report Share Posted January 3, 2019 During the recent annual on our '67C, my A&P flagged the rudder free-play as being out of spec. The service manual on page 6-7 lists the free-play limit as 0.08" (80 thousanths of an inch!). He observed three push-rod ends in the empennage seem to account for most of the excess free-play. Has anyone dealt with this problem? Looking at Fig. 29 in the parts manual, which is not real detailed, aft of the tail cone rear bulkhead there are bushings and possibly Heim bearings that could be worn and produce free play. Is it best to just replace push rods? Looking for experienced advice so I can start to identify what parts I might need and where they can be had. Thanks in advance, and Happy New Year! Quote Link to comment Share on other sites More sharing options...
RLCarter Posted January 3, 2019 Report Share Posted January 3, 2019 Aren’t there rod end bearings on the pushrods you can replace rather than the whole tube assy? Quote Link to comment Share on other sites More sharing options...
orionflt Posted January 3, 2019 Report Share Posted January 3, 2019 Just check the hardware for wear and replace the hiem bearings. Brian Quote Link to comment Share on other sites More sharing options...
Prior owner Posted January 3, 2019 Report Share Posted January 3, 2019 (edited) Most, if not all of the joints in the rudder system are not the screw-in type...they are part of a plug that is either welded to the tube, or pressed in and locked with roll pins. Call LASAR- they have these pushrods made for them. I’ll have to look at the rudder system again, but I know that with the ailerons, you can swap the right and left pushrods (same part number) from the yokeshafts to give yourself a little less play while flying the left seat (assuming the rod ends are less worn on the right side, as mine were...). Edited January 3, 2019 by PilotCoyote 1 Quote Link to comment Share on other sites More sharing options...
Andy95W Posted January 3, 2019 Report Share Posted January 3, 2019 That .08" measurement is the allowable vertical play per the service manual (for hinge play). If that was the linkage slop, every Mooney in the world- to include brand new ones from the factory- would be unairworthy. Your A&P should read the page more closely- there isn't a published number for linkage play. As with most airplane types, it's up to the individual A&P and what they think is appropriate (or not). 1 Quote Link to comment Share on other sites More sharing options...
gsxrpilot Posted January 3, 2019 Report Share Posted January 3, 2019 And if the vertical play is just out of spec... just adjust the trim. The vertical slop varies by where the trim is set. Quote Link to comment Share on other sites More sharing options...
Guest Posted January 3, 2019 Report Share Posted January 3, 2019 The joy of Mooney flight controls, many rod end bearings to wear out adding play to the system. One can argue that with no stated limits it doesn’t matter, or that with no limits no play is allowed, its up to your maintainer to decide. Along with worn rod end bearings, the walking beam in the tail cone OS prone to wear. Mooney left 2 holes in the upper stab skin which allow water to run into the bearings. It’s a bit of a challenge to remove and replace the bearings, Torrington B-47 times 2. The rod end bearings for the most part are secured to the tube with roll pins. They are not really difficult to replace, a good set of sharpe number drill bits, a drill press, new roll pins from Mooney and a carefull maintainer. I’ve seen the tubes scraped when the holes in the tube were drilled oversized. I drill one hole, tap the new roll pin in part way, then flip it over and drill the opposite side, repeat for the cross pin. Drive the first pin out, noting bearing orientation, blow drill shaving out, spray in some LPS 3, reinstall the bearing and secure with new pins, lightly flair the ends of the rolls pins with a centre punch. Clarence Quote Link to comment Share on other sites More sharing options...
0TreeLemur Posted January 4, 2019 Author Report Share Posted January 4, 2019 51 minutes ago, Andy95W said: That .08" measurement is the allowable vertical play per the service manual (for hinge play). If that was the linkage slop, every Mooney in the world- to include brand new ones from the factory- would be unairworthy. Your A&P should read the page more closely- there isn't a published number for linkage play. As with most airplane types, it's up to the individual A&P and what they think is appropriate (or not). Ok, so I see the word "vertical" in the free-play limit given on page 6-7 of the maint. manual. I do recall him telling me that with push rods, he expects the total play in the system should be less than 1/8". I suppose when a 1/8" along-axis play is converted into rotational play by the moment arm of the offset linkage at the rudder, it might easily be amplified by a factor of more than 4 or 5. That is 1/2 to 5/8" of side-to-side play in the rudder. Is that typical? If so, then my plane doesn't have a problem it seems. Quote Link to comment Share on other sites More sharing options...
Browncbr1 Posted January 4, 2019 Report Share Posted January 4, 2019 Part of your preflight should include giving a slight lift on the bottom of the rudder to confirm no slop. Not much force is needed. I just lift up with one hand maybe 5-10lbs of force. If you hear or feel any movement, look into it more closely. 2 Quote Link to comment Share on other sites More sharing options...
Guest Posted January 4, 2019 Report Share Posted January 4, 2019 39 minutes ago, Fred_2O said: Ok, so I see the word "vertical" in the free-play limit given on page 6-7 of the maint. manual. I do recall him telling me that with push rods, he expects the total play in the system should be less than 1/8". I suppose when a 1/8" along-axis play is converted into rotational play by the moment arm of the offset linkage at the rudder, it might easily be amplified by a factor of more than 4 or 5. That is 1/2 to 5/8" of side-to-side play in the rudder. Is that typical? If so, then my plane doesn't have a problem it seems. I have a piece of aluminum “C” channel in the shop which I drop over the copilot rudder pedals(assuming now brake pedals) this locks the pedals from moving. Gently wiggle the rudder trailing edge and start examining all of the rod ends and bearings in the system until you find the source of the play, seldom is it just one piece. With 1/2-5/8” play the rudder travel will likely be less than specified travel which does not meet type certificate limits. Clarence Quote Link to comment Share on other sites More sharing options...
0TreeLemur Posted January 4, 2019 Author Report Share Posted January 4, 2019 So we did what you suggest. With rudder pedals clamped, looking through the inspection port on the left side of the empennage, you could see some relative motion in the three bearing ends in view. No motion was apparent forward of the tail cone bulkhead including the tail cone bell crank. My A&P concluded that those three Heim bearings and/or bushings are worn and in need of replacement. Clarence, ( @M20Doc ) will you clarify your statement: "With 1/2-5/8” play the rudder travel will likely be less than specified travel which does not meet type certificate limits.", what is the specified travel? All I see on the type cert. for rudder are +-23 to 24 degree travel limits. Are you saying that this is the important spec? My A&P was worried about flutter. Thanks,. Quote Link to comment Share on other sites More sharing options...
Guest Posted January 4, 2019 Report Share Posted January 4, 2019 (edited) 24 minutes ago, Fred_2O said: So we did what you suggest. With rudder pedals clamped, looking through the inspection port on the left side of the empennage, you could see some relative motion in the three bearing ends in view. No motion was apparent forward of the tail cone bulkhead including the tail cone bell crank. My A&P concluded that those three Heim bearings and/or bushings are worn and in need of replacement. Clarence, ( @M20Doc ) will you clarify your statement: "With 1/2-5/8” play the rudder travel will likely be less than specified travel which does not meet type certificate limits.", what is the specified travel? All I see on the type cert. for rudder are +-23 to 24 degree travel limits. Are you saying that this is the important spec? My A&P was worried about flutter. Thanks,. When your airplane was born and everything was new with no wear, Mooney adjusted the flight control travel stops to,meet the travel limits stated in the maintenance manual as well as the type certificate. As your plane aged and system rod end wore out the controls will no longer travel the required number of degrees. While you could push the rudder by hand to the full travel. Depending on where the wear in the system is, it can prevent the rudder from reaching full travel while sitting in the pilot’s seat pushing on the rudder pedal. Failure to to meet limits specified in the type certificate renders the plane technically un airworthy. Clarence Edited January 4, 2019 by M20Doc Quote Link to comment Share on other sites More sharing options...
carusoam Posted January 4, 2019 Report Share Posted January 4, 2019 Great details, Doc! Thanks for sharing them. Best regards, -a- Quote Link to comment Share on other sites More sharing options...
MB65E Posted January 4, 2019 Report Share Posted January 4, 2019 Thanks Again for the B-47 PN doc. It’s hard to find. I’ll finish mine one of these days! ebay has a LOT of 25 of them for $60! What a deal! -Matt Quote Link to comment Share on other sites More sharing options...
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