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DHeal

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    Santa Rosa, CA
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    Flying my RV-12 E-LSA
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  1. When checking the module wires noted above by Roger, also check that the ignition switches and their associated wiring are working correctly. An intermittent ignition switch (e.g., internal failure) or intermittently shorting ignition control wire could cause the issue you are experiencing.
  2. Loctite 567 has worked very well for me over the years. It seems impervious to oil and fuel (100LL and mogas w/ ethanol).
  3. Interesting new note (P.2-4) in recent update (1/1/23) of Rotax 912 Series Operators Manual: NOTE Low fuel pressure indications are possible and allowed. But the pressure must stabilize to the operating limit within 10 seconds. If not, the cause should be determined and rectified. Due to the technical design and installation conditions (construction of the return line, etc.) pressure fluctuations, at the fuel pump are possible. These pressure fluctuations within the specified operating limits are not considered a problem.
  4. "....Although the Flight Designs are not permitted "Flight Into Known Icing Conditions", it would seem to me that perhaps we should consider adding a vent hole to the engine breather at the bottom of the engine compartment as a point of safety should inadvertent icing be encountered...." It is not just "Flight Into Known Icing Conditions" or "inadvertent icing" that is the concern -- flying along on a beautiful but freezing VMC day can also be of concern. The crankcase vent spews out water as a normal by-product of engine combustion. When this exiting water gets cold enough near the exit point of the vent line it may freeze thus causing blockage of the line leading to increased crankcase pressure and potential failure of the crankshaft/crankcase seals. I suspect that for the Rotax 900-series engines with its remote oil tank this increasing back-pressure would additionally interfere with the proper return of residual crankcase oil to the oil tank and possibly result in other internal oil flow issues.
  5. For water pump seals, see Figure 1 and Paragraph 1.5 "Note" at: https://legacy.rotaxowner.com/si_tb_info/serviceinfo/si912001.pdf
  6. Yikes! Fuel dripping from the carbs is not good. Do both carbs drip or just one side?* Some troubleshooting thoughts: 1) Poor bowl gasket and/or poor bowl gasket seal -- IMHO the original cork gaskets are lousy -- I have had great success with the green composite gaskets; 2) Worn float needle valve and/or needle valve orifice -- see Rotax manual for test procedure in this regard; 3) Excessive fuel pump pressure is overpowering float needle valve assembly -- see Rotax manual for test procedure in this regard. My money is on #1. *If only one carb is dripping it is likely a problem with that one carb. If both carbs are dripping it could be a system problem -- excessive fuel pressure??
  7. I use the twin-gauges style on my 912 ULS and find it easy to use and decipher. Another possibility is to find an old but accurate twin-engine aircraft manifold pressure gauge.
  8. Back in the day flying students in frigid upstate NY we relied on Red Dragon propane-fired aircraft heaters. They were portable, 12-volt battery-operated space heaters designed specifically for aircraft pre-heat use. I have heard that they are no longer manufactured (?) but perhaps you can find a used one. The backcountrypilot.org forum generally has a lot of information regarding engine pre-heating. ps -- MEH's post regarding "clearances" is spot on. You can get most any cold engine to "start" but what long-term internal damage have you inflicted in the process?
  9. I do not know how your ignition modules control switches ("mags") are specifically wired in your aircraft. The ROTAX 912 Major Maint Manual has the generic wiring diagram for the ignition system. Knowing which of your switches controls which module/set of spark plugs will aid you in your troubleshooting. You could just replace all of the newly-installed spark plugs with the old used set of proven spark plugs (or a different set of new spark plugs) and see if the problem goes away. If the problem persists, perhaps trimming of the ignition leads is in order. The connectors "unscrew" from the wires.
  10. If you have an EGT probe on each of the four cylinders, you should see a rise* in the EGT temp on the cylinder with the misfiring spark plug/lead. Check that cylinder's spark plug's resistance (http://www.ngk-sparkplugs.jp/english/techinfo/qa/q08/index.html) or just replace the suspect spark plug. In addition, you could trim off the end of the plug's lead and reset the plug's connector. * The inefficient and prolonged burning of the single-plug combustion gases causes the EGT to increase.
  11. The EGT can also be used to troubleshoot a defective spark plug (or associated wire) -- if the engine is running rougher than usual and the EGT is higher than usual in the specific EGT cylinder then one of the two spark plugs may not be firing correctly. This results from partially combusted burning gases flowing past the EGT probe.
  12. It is my understanding that the new-style spark plugs ($22 each) require a new-style boot connector ($40 each) be installed on each spark plug wire. The new-style plugs are not compatible with the old-style boot connectors. Does anyone know if the old-style spark plugs will still be manufactured by NGK to be used on non-aircraft products (e.g., snowmobiles, motorcycles, etc.)?
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