Trim Relay Replacement
Interestingly, after comparing notes with 2 other RV-10 fliers, we've all had recent issues with our elevator trim relays, the REL-1 from Ray Allen. Mine started to stick occassionally at about 250 hours. Another person's at a little over 200 hours, and the third was just having the problem for the second time at 490 hours (previously replaced a year prior). We did hear from a 4th who had issues within the first few hours also. At OSH 2007 we were able to talk to Ray Allen's president, Gary Menzimer, at the show, and he noted that they've seen an increase in the number of bad relays in the last year or so. The only changes from their old reliable relays is that the new stuff is made with the lead-free RoHS compliant process. He did tell me that it's a physical sticking of the relay, and if you rapped on it, it would release, and I've found that to be true.The failure mode is that you will be trimming in one direction and when you go to trim opposite it won't go back. The actual failure, however, was happening on that initial trimming, as it didn't complete the trim process of returning the relay to the position where it grounds both trim motor leads.
Ray Allen was nice enough to give us new relays, the REL-2, which has now replaced the REL-1. It's a little heavier duty, and not the same footprint, but they've been running it thousands of hours now testing it and not seen problems. Some builders also commented that there are other relay options out there, such as a self-designed solid-state relay, or the Aircraft Extras relay board, or a popular one from our own Matt Dralle of the Matronics list, the Matronics Governor MkIII that also includes speed control in a small reliable solid-state package. For simplicity of getting it fixed quick, I installed the REL-2, but should I ever experience another issue, I'll be going a solid-state route.
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Additional resources:
http://www.rayallencompany.com/RACmedia/instructionsREL.pdf
http://www.rayallencompany.com/products/accessories.html