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Frequently Asked Questions about magnetos

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  1. What is the overhaule interval of magnetos?
  2. My magnetos reached the TBO but run without any problem, why should they be inspected?
  3. My magnetos only run a couple of hours in the last years, should they be checked?
  4. What is going to be checked at a 500h inspection, and at an overhaul?
  1.  What is the overhaul interval of magnetos?


    TCM Bendix

    For all models (S-20/S-200, D-2000/D-3000, S-1200) applies

               500 hrs inspection – after an operating time of 500 hrs 

               Overhaul – latest after 4 years in use or 5 years on shelf

    Overhaul – in case of Overspeed, Sudden Stoppage and motor-overhaul an overhaul  is necessary

    (With SB643A TCM does not require an interval inspection only on the magnetos but also on the harness, ignition switch and starter vibrator.

    For S20/S200 and S-1200 also applies

               magnetos with serial number after June 2015 need to be overhauled „only“  after 12 years in service. Older magnetos must be overhauled after 4 years in service.

               (in case of factory overhauled magnetos, the serial number stays the same, therefore   this change only applies for factory new TCM magnetos).

     

    Slick

    For all models (4200/6200 & 4300/6300)

    100 hrs inspection – performed on the motor

    250 hrs/2 years inspection – on engines with single ignition (motor gliders) & pressurized magnetos

    500hrs inspection – for all engines with double ignition system

     

    Additionally for new style models (series 4300/6300)

                Overhaul – general overhaul after 12 years

    Additionally for older style models (series 4200/6200)

                1000 hrs Inspection

                Overhaul – general overhaul together with the engine




  2. My magnetos reached the TBO but run without any problem, why should they be inspected?
    In aerospace we most times talk about inspection not repair. It’s like it should be at every inspection. The FBO should inspect if every part is still working proper, and he should make sure that axels or bearings run smooth and get new grease and Oil. A lot of smaller defects don’t show up at first. The shrinking power is most times not recognized because it comes slowly. Other problems are shown right at the start of the engine. Or they cause a higher consumption.




  3. My magnetos only run a couple of hours in the last years, should they be checked?
    Yes, this regulations are airworthiness directives.

    A mayor problem of the general aviation is the small runtime of the aircraft engines and aggregates. A lot of parts wear more because of rust than because of working. An inspection is always recommendable.




  4. What is going to be checked at a 500h/ 4 years inspection?
    This question has to be answered separately for the two main magnetos Unison/Slick and TCM/Bendix.

    Unison/Slick
    The magneto is going to be mostly disassembled and cleaned. All parts are proved for applicable SB’s (Service Bulletin) The ignition coil and the condenser are tested for their electrical tolerances and with a separate tester for hardware defects. The distributor block and the distributor gear electrode are cleaned from contaminants. All parts are visually – if needed with a 3D microscope – checked. The main contact, cam, screws of the main contact and gaskets for pressurized magnetos are replaced. After the assembly the magneto is tested with different speeds on our magneto bench.
    Every part of our control is written down at a detailed maintenance report including all tolerances required. You will receive an EASA FORM ONE with every inspected magneto.

    TCM/Bendix
    The magneto is completely disassembled and cleaned. All parts are checked for SB’s and LTA’S (German airworthiness directives). The housings are sandblasted and newly varnished (priming & varnishing) if they are in bad conditions. The ignition coil and the condenser are also tested for their electrical tolerances and with a separate tester for hardware defects. The distributor block and the distributor gear electrode are cleaned from contaminants. Afterwards the distributor block will be deoiled, cleaned and oil again at 100 degree Celsius (the oiling takes one hour in the oven). Depending on the material of the distributor block it will receive new doping. All other components are cleaned in an ultrasonic wash-basin. Replaced are the main contact, felt strip and –washer, self-locking screws and the spring for the impulse coupling. Newly lubricated the magneto will be assembled. After the assembly the magneto is tested with different speeds on our magneto bench.
    Every part of our control is written down at a detailed maintenance report including all tolerances required. You will receive an EASA FORM ONE with every inspected magneto.