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Hello, I noticed during a pre-flight inspection that the 914F3 engine was powered by two electric fuel pumps (primary and secondary), with no mechanical pump in sight. This seems unusual to me and doesn’t align with best practices, as it makes the aircraft reliant on the electrical system. However, the owner assured me that this is a common practice. Do you have any thoughts on this?

  • Re: 914 using only electric fuel pumps

    by » 3 months ago


    Hi Georges, yes that is correct. The 914 engine does not have a mechanical fuel pump. It is my understanding that the fuel pressure & flow requirements at high power are such that electric pumps only, are the solution. The installation requires consideration of redundancy within the electrical system design in regards to the fuel pumps.

     


    Thank you said by: Georges Maheu

  • Re: 914 using only electric fuel pumps

    by » 3 months ago


    If the 914 electrical and fuel systems are designed correctly and the installation manual has been followed, redundancy is ensured.

    The electric fuel pumps must be wired correctly to achieve this redundancy. The main pump is powered by the alternator/generator, while the Aux pump is powered by the battery. In the event of generator failure, the Aux pump will continue to receive power until the battery depletes (approximately 30 minutes, depending on the electrical load). If the battery fails, the main pump will still be powered by the alternator/generator.

    It's worth noting that the AUX pump should be turned off following take-off (at a safe altitude) to avoid having both pumps running simultaneously all the time. A simplified (unofficial) wiring diagram is provided to aid in understanding how the system is connected.

     

    39263_2_FuelPumpSchematic.pdf (You do not have access to download this file.)

    Thank you said by: Georges Maheu

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