Hivemind - I am experiencing an anomaly that I am having a hard time generating a hypothesis on why it is happening.
Aircraft is RV-10, dual PMAGS, AFS4500 EFIS.
Symptom: The RPM reading goes all over the gauge when Fuel is pump is switched on (all the way to zero and 2650 and oscillating in between). The RPM itself is steady, it's just the display. On top of it, this happens once in a while (~one out of five flights). Tach signal is being pulled from PMAG, which is installed as per the instructions.
Here is what I could hypothesize:
1) Corrosion or loose terminal. (But why the anomaly occurs when fuel pump is on).
2) Possible EMI when current is flowing to the fuel pump. (But why does it happen only once in a while)?
What else should I be thinking about?
Aircraft is RV-10, dual PMAGS, AFS4500 EFIS.
Symptom: The RPM reading goes all over the gauge when Fuel is pump is switched on (all the way to zero and 2650 and oscillating in between). The RPM itself is steady, it's just the display. On top of it, this happens once in a while (~one out of five flights). Tach signal is being pulled from PMAG, which is installed as per the instructions.
Here is what I could hypothesize:
1) Corrosion or loose terminal. (But why the anomaly occurs when fuel pump is on).
2) Possible EMI when current is flowing to the fuel pump. (But why does it happen only once in a while)?
What else should I be thinking about?
