i have a very annoying problem, i have noises in my headset, only when engine is running.
On the ground with no engines and every electrical instrument on i have no noises, just when the engine is running, and still without avionic.

Does anyone know what part of the engine causes such problems ? I'm desperate... I have the 912S.

Best regards from Germany
  • Re: Noises in Headset when the engine is running

    by » 5 years ago

    You need to divide an conquer:
    Are you P-leads (shorting wires/ignition switch wires) shielded? Is the shield well grounded at the switch and/or at the CDI modules?
    Try switching off 1 mag and then the other, does the noise change?
    Does the noise change with RPM?
    Disconnect plug on regulator to see if it is generator noise. Is the shield on the yellow wires grounded to the engine? (stainless steel clamp
    Do you have the 22,000mf capacitor for the regulator?
    You may have a ground loop in the intercom. You need an avionics tech for that.

  • Re: Noises in Headset when the engine is running

    by » 5 years ago

    Noise in the radio / intercom system is a very common problem. Alot can happen to the current as it travels to the radio (as Ron also writes), which can create noise:
    Noise from the alternator (generator), from 12v to 5v converters (USB sockets) installed, noise from (poorly shielded) cables running close to each other such as antenna - intercom wires etc.

    Try to unplug the positive (+) supply into the radio / intercom unit, then put a wire directly from the battery to the radio / intercom.
    Preferable with a fuse, 4-8A.

    If this clears the noise (when the engine is running), you will know that the noise comes from the electrical system. If not, suspect noise from intercom wires due to interference with other cables.

    Good luck :)

  • Re: Noises in Headset when the engine is running

    by » 5 years ago


    Are you using 'resistor' type plugs? I had lots of ignition noise from my 914 until I started using resistor plugs which almost totally eliminated it for an easy inexpensive repair.


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