Rich Posted October 13, 2015 Report Share Posted October 13, 2015 Good afternoon, I'd like to install a back up RPM steam gauge for my SLSA. Been having problems with the EFIS/EDM fluctuating. Now it reads in the 500/800 range. It needs to go back to Tru Trak for a fix. What type is best? Where would the pick up hook up to on the 912 ULS? (2012 model) Thanks, Rich Link to comment Share on other sites More sharing options...
Anticept Posted October 13, 2015 Report Share Posted October 13, 2015 The rotax installation manual will tell you everything about the tach pickup. It is electronic. Link to comment Share on other sites More sharing options...
Rich Posted October 13, 2015 Author Report Share Posted October 13, 2015 Thanks Corey, I went to the manual and found the pick-up on Page 17-2. Question----------Can the signal from the pick up supply both the EFIS and the additional RPM gauge? Link to comment Share on other sites More sharing options...
Anticept Posted October 13, 2015 Report Share Posted October 13, 2015 Hard to say. I want to say it is very likely, you'll just have to try and see, or ask an avionics guru. But first, have someone check the pickups. They need to be a set spacing from the flywheel (REALLY SMALL! spec is in tenths of a millimeter!). When they are outside of their operating range, you will see strange effects like wrong RPM indications, or misfires if it's one of the ignition pickups. Rotax calls them "trigger coils". The spec is found in the heavy maintenance manual. If you know how to use an oscilloscope, you can use that to verify if the pickups are functioning properly (heavy MM has information). If the pickups are difficult to get to, like on CTs, I'd go this route. Make sure the trutrak is malfunctioning while the o-scope says things are working so you KNOW it's the trutrak and not an intermittent problem with the pickups. You might have to ask trutrak what the counter amplitude needs to be too, it could look like it's working yet not be a high enough trigger voltage for the trutrak to function (bad trigger coils, improperly spaced trigger coils, connector corrosion, etc). It can also be an issue with the connector or wiring up to the trutrak, so check those too. Link to comment Share on other sites More sharing options...
Rich Posted October 13, 2015 Author Report Share Posted October 13, 2015 I'll check all connections tomorrow. I've had this problem since new. I usually just pull the EFIS CB out to reset and it'll work fine for a day or so until it happens again. Resetting the CB doesn't help anymore. The pick-up I was talking about had a snap plug (# 7 in the diagram) coming from either module A or B that the Tru-Trak male plug should go into. I guess I used the wrong phrase. It was the connection point for the EFIS after the pick-up. Link to comment Share on other sites More sharing options...
Anticept Posted October 13, 2015 Report Share Posted October 13, 2015 The tach pickup is its own pickup, it has no relation to the other 4 (2 per module). There are 5 pickups total. If this is something that always rectifies itself when you reset it, then it probably is the TruTrak unit. What diagram? Also, you said page 17-2 earlier, which manual is that? If you mean the rotax manual, you need to give the chapter number too (format xx-xx-xx). Rotax sets their manuals to the ATA 100. Link to comment Share on other sites More sharing options...
Roger Lee Posted October 13, 2015 Report Share Posted October 13, 2015 The rpm signal can only handle one output. You probably won't be able to run two. I have seen some try, but it didn't work out. The air gap on the pickup may need adjustment. You can also check the tach trigger coil with an ohm meter. My guess is the air gap or a bad wire connection. Link to comment Share on other sites More sharing options...
Anticept Posted October 13, 2015 Report Share Posted October 13, 2015 The rpm signal can only handle one output. You probably won't be able to run two. I have seen some try, but it didn't work out. If a guy is experimental, he could make a small repeater circuit then if he knows how :-) Link to comment Share on other sites More sharing options...
Rich Posted October 13, 2015 Author Report Share Posted October 13, 2015 The tach pickup is its own pickup, it has no relation to the other 4 (2 per module). There are 5 pickups total. If this is something that always rectifies itself when you reset it, then it probably is the TruTrak unit. What diagram? Also, you said page 17-2 earlier, which manual is that? If you mean the rotax manual, you need to give the section number too (format xx-xx-xx). Rotax sets their manuals to the ATA 100. It's the one you said to look at in your first post. The Rotax installation Manual. Section17-2 shows the diagram. Link to comment Share on other sites More sharing options...
Anticept Posted October 14, 2015 Report Share Posted October 14, 2015 I apologize, but I'm not sure what section "17-2" is, so I'm having difficulty following you... This document is the install manual: http://docusearch.flyrotax.com/files/pdf/d06047.pdf In the lower right corner, you will see this: 79-00-00 Page 17 Which is the section chapter & page number showing the oil cooler. (Sections are known as "chapters," and I really should be calling them chapters since that's how it is written in the manual :-) Link to comment Share on other sites More sharing options...
Rich Posted October 14, 2015 Author Report Share Posted October 14, 2015 Corey, Browser search for Rotax installation Manual Find Rotax 912 installation Manual: Rotax installation Manual/ 912S Table of contents, Scroll down to 17 Electrical systems, Scroll down to 17-1 for the diagram. Link to comment Share on other sites More sharing options...
Anticept Posted October 14, 2015 Report Share Posted October 14, 2015 Rich, that is the wrong manual. The 912s is the certified engine. The documentation will probably have differences. I also can't do a browser search, I will NOT get the same results as you, as all major search providers do some sort of search personalization (prioritizing local services). You will have to provide a link to the document you are looking at. I'd like to share how aircraft maintenance manuals work if you would allow me. It would be extremely helpful if we are to continue. Please see: http://ctflier.com/index.php?/topic/3471-how-to-reference-maintenance-manuals/?p=48784 I would suggest we use this moving forward: http://docusearch.flyrotax.com/files/pdf/d06047.pdf Link to comment Share on other sites More sharing options...
Philip Welsch Posted October 14, 2015 Report Share Posted October 14, 2015 How about a TRU-TACH or one of the other optical, digital tachs set on the glareshield? PRW Link to comment Share on other sites More sharing options...
Roger Lee Posted October 14, 2015 Report Share Posted October 14, 2015 The 912UL, ULS and the 912s install manual is the same and you can find current editions on the Rotax website or the Rotax Owner website that anyone can download. Just a note. If there is a certified 912S in an LSA a RLSM-A can work on it. Link to comment Share on other sites More sharing options...
Anticept Posted October 15, 2015 Report Share Posted October 15, 2015 I just checked, you are right, they are the same. Still, I can't figure out what Rich is looking at. Since he said browser search, he probably has found some really old document. I just did a search on google and a whole bunch of results came up, and some of them are really old. EDIT: check this old thing out heh: http://aeroelectric.com/Mfgr_Data/Rotax/Rotax_912S_IM.pdf. Back then they were indeed different documents. Link to comment Share on other sites More sharing options...
Roger Lee Posted October 15, 2015 Report Share Posted October 15, 2015 Check here for current manuals http://www.rotax-owner.com/en/support-topmenu/engine-manuals Link to comment Share on other sites More sharing options...
Tom Baker Posted October 15, 2015 Report Share Posted October 15, 2015 I know a fellow who had a steam gauge tach installed in his Tecnam. I don't have access to the airplane to see how the installation was done. You might check with the West coast Tecnam dealer, because they were the one who did the installation. Link to comment Share on other sites More sharing options...
Rich Posted October 15, 2015 Author Report Share Posted October 15, 2015 All, The web search I used turned up an older manual like you had mentioned, However, the connection point that I was looking for was accurate. I went to the airport yesterday and found the connector next to the ignition modules. The connection is fine. The multi-pin connectors going into the EFIS/EDM also looked good. The unit will be returned to TTrak. Until then, what's the concensus of flying without a proper tach read out for a long x/c? I'm okay with it, I think? Naturally we know the engine sounds and can be pretty sure of where we're at. I would like your thoughts on this. Thanks to all who've responded and spent time on this. Rich Link to comment Share on other sites More sharing options...
Anticept Posted October 15, 2015 Report Share Posted October 15, 2015 Flying without a tach is a very bad idea. It's one of the first places you notice loss of power in the case of carb icing and making sure you are getting full take off power. I was going to quote the 91.205 requirement for a tachometer for flight, but it only says standard airworthiness aircraft. Still, I imagine this will be a required item by the equipment list, and I don't imagine you'll get your manufacturer to approve an MEL (not sure if MEL exists for SLSA anyways) without a tach. Link to comment Share on other sites More sharing options...
Tom Baker Posted October 15, 2015 Report Share Posted October 15, 2015 It is likely a required item by ASTM. Link to comment Share on other sites More sharing options...
Rich Posted October 16, 2015 Author Report Share Posted October 16, 2015 How about the Tiny Tach as a back-up? I used it as a back up on my Rotax 503 when I was flying experimental and it never missed a beat. I don't think it would be an approved instrument for an SLSA but I really want the back up. The pick-up wire just needs 3 or 4 turns around any spark plug wire to work. I know they make them for 2 and 4 cycle engines. It can be velcroed in place. Simpler is better. Never had any problems with the steam gauges. Now I have a state of the art machine with recurrent glitches that's a PITA. Link to comment Share on other sites More sharing options...
Anticept Posted October 16, 2015 Report Share Posted October 16, 2015 503 is a 2 stroke, the 912 is a 4 stroke. There's twice as many firing events in a 503. You'll either need to see if you can change a setting on the Tiny Tach, or remember to double what you see on the tach. EDIT: Disregard, having a brief "stupid" moment. All plugs fire on every stroke in rotax 912/914 carb series, there is no distributor and they don't make an effort to simulate one electronically. Link to comment Share on other sites More sharing options...
Rich Posted October 16, 2015 Author Report Share Posted October 16, 2015 Corey, I'd get the 4 stroke unit and then it should read correctly. I'm going to look it up in the ACS catalog. Thanks, Rich Link to comment Share on other sites More sharing options...
Tom Baker Posted October 16, 2015 Report Share Posted October 16, 2015 Corey, I'd get the 4 stroke unit and then it should read correctly. I'm going to look it up in the ACS catalog. Thanks, Rich Except as Corey mentioned the 912 waste a spark. It has a spark at top of the stroke regardless of whether it is the compression or exhaust stroke. This would make it like a 2 stroke in regards to ignition. Link to comment Share on other sites More sharing options...
gbigs Posted October 16, 2015 Report Share Posted October 16, 2015 Here is a set of backup tachs for Rotax: https://www.aircraftspruce.com/menus/in/tachometers_rotax.html Here is a backup EFIS for Rotax: http://www.flyboxavionics.it/en/minieis.html Here is a PDF for Rotax wiring: http://www.ultralightnews.ca/rectifiers/912regulatorrectifernstallation.pdf Link to comment Share on other sites More sharing options...
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