warren.huisman Posted January 21, 2019 Report Posted January 21, 2019 I have kind of a weird scenario which does not make sense to me. Flew the airplane today and was not getting RPM readings in flight. I have noticed that if I lower the RPM to around 2200 RPM, it will bounce between 3-600 and 2200(ish). Any higher RPM, it was displaying the tach time (engine hours) of the airplane. (I have a VM1000 which displays the tach time (engine hours) when the engine is off. ) Once on the ground, the tach was working perfectly. I even did a run up to ~2400 RPM on the ground and it was fine. The tach time (engine hours) is not increasing correctly either. The manual says the engine time will accumulate when the engine is running above 1500 RPM. Seems like a loose connection or bad RPM pick-up but why would it work on the ground? Looking for ideas Quote
carusoam Posted January 21, 2019 Report Posted January 21, 2019 1) find rpm sensor. 2) chase wire back to VM1000. 3) exercise every connection in between. 4) use electronics cleaner during the exercise. 5) Engine hours and rpm are using the same sensor in many cases. Even the mechanical tach does it this way.... 6) The VM1000 is one of the oldest digital grapghic (?) engine monitors on the planet... Stuff corrodes Or gets dirty in its life. There are particular vibrations that make some things work better, or worse... PP thoughts only, not an instrument guy... Best regards, -a- Quote
warren.huisman Posted January 26, 2019 Author Report Posted January 26, 2019 Root cause seems to be the rpm sensor. It came out of its housing when I was checking the terminations. Pushed it back it and it works. Not sure how long before it comes out again Sent from my iPhone using Tapatalk Quote
carusoam Posted January 26, 2019 Report Posted January 26, 2019 Warren, got a pic? Something should be holding it in place... With the age of the VM1000 system, anything could be possible... design criteria? Age of the sensor and it’s holder...? Hard to set power without an RPM gauge... Good time to download a plan B... get the rpm app for your smart phone. PP thoughts only, not a mechanic... Best regards, -a- Quote
warren.huisman Posted January 27, 2019 Author Report Posted January 27, 2019 (edited) Unfortunately I didn't take a picture . I put some gasket material over it to help it stay in place. Been trying to figure out where to find a replacement as this solution is probably temporary. I guess I'll be putting in a phone call to JPI. At least I'll get to experience there customer service first hand. A EDM-900 should fit right in. Why are they so expensive compared to the 830s? Doesn't seem to do much more. The I-phone RPM app looks interesting. Any experience in an airplane in flight? Edited January 27, 2019 by warren.huisman Quote
carusoam Posted January 28, 2019 Report Posted January 28, 2019 https://mooneyspace.com/search/?q=Rpm app&sortby=relevancy&search_and_or=and Warren, Search down the titles... there have been quite a few people using an app to verify the engine rpm... compared to the tach. Simple technology actually... Best regards, -a- Quote
Yetti Posted January 28, 2019 Report Posted January 28, 2019 Some people use and optical tach to check their tach. Look at the hobby store. The phone apps seem reliable also Quote
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