Turbine RPM display rolling over
Posted: Sat Jun 05, 2021 7:52 pm
Hello All.
A friend (who isn't on this forum) and I are both flying turbine powered helicopters whose engines turn at a nominal 61500 RPM, and the sensor sees 20 pulses per revolution (2050HZ@61500). He is running an iEFIS Explorer Lite with an RDAC and is having a display problem with the Turbine RPM (connected to RPM1 on the RDAC). The display climbs normally but drops back to zero at around 50% RPM and then continues up again from there. I remember Rainier posted something a few years back regarding an update to the iBox system: "This fixes a scaling issue that can affect installations using a relatively high number of pulses per engine revolution. <snip> You only need to do this update if your RPM calibration multiplied by your maximum engine RPM will exceed the value 32767." This seems suspiciously close to the 32000 RPM fold over he was reporting. Issue is, the Lite version doesn't have an iBox... And he is running the latest firmware version on his RDAC and has played with the RPM filter and sensitivity adjustments, no joy.
Any suggestions?
I'm particularly interested in this as I've just finished wiring my Turbine RPM into the RDAC/RPM1 on my _Standard_ Explorer (with iBox) and, based on Rainiers earlier post, had expected this to work when I button up and fire the engine, but now I'm curious if there might be something else that might be going on.
Any help appreciated...
Tim Drnec
Helicycle 202AP
A friend (who isn't on this forum) and I are both flying turbine powered helicopters whose engines turn at a nominal 61500 RPM, and the sensor sees 20 pulses per revolution (2050HZ@61500). He is running an iEFIS Explorer Lite with an RDAC and is having a display problem with the Turbine RPM (connected to RPM1 on the RDAC). The display climbs normally but drops back to zero at around 50% RPM and then continues up again from there. I remember Rainier posted something a few years back regarding an update to the iBox system: "This fixes a scaling issue that can affect installations using a relatively high number of pulses per engine revolution. <snip> You only need to do this update if your RPM calibration multiplied by your maximum engine RPM will exceed the value 32767." This seems suspiciously close to the 32000 RPM fold over he was reporting. Issue is, the Lite version doesn't have an iBox... And he is running the latest firmware version on his RDAC and has played with the RPM filter and sensitivity adjustments, no joy.
Any suggestions?
I'm particularly interested in this as I've just finished wiring my Turbine RPM into the RDAC/RPM1 on my _Standard_ Explorer (with iBox) and, based on Rainiers earlier post, had expected this to work when I button up and fire the engine, but now I'm curious if there might be something else that might be going on.
Any help appreciated...
Tim Drnec
Helicycle 202AP