> I was researching the failure on John Slades EC2 and found some
          > disturbing things.
          >
          > The input power filter uses a choke which is the only single
    failure
          > point in the EC2. The part was originally specified to be so
    over
          > rated such that failure could only be caused by physical
    damage to
          > the part. If an overload occurred sufficient to fail this
    part, the
          > circuit traces on the board would fail long before the part
    would.
          > This
          > was the rationale for the basic design approach. Don't want
    to get
          > into
          > a discussion of why separate chokes are not used.
          >
          > At some point the manufacturing facility substituted a
    different part
          > with same inductance but lower current rating. It was still over
         rated
          > and sufficient for any foreseeable situation so it was
    considered OK.
          >
          > Still later, the board maker substituted an even lower rated
    part
         that
          > looks almost identical to the previously substituted part. I
    was not
          > informed of this change. The unit will function normally
    with this
          > part but it has no extra margin for safety in the event of
    mis wire,
          > shorted output, etc. I was able to duplicate the failure
    John Slade
          > had
          > by shorting 1 or more ignition driver outputs to ground or
    12V input
          > power. The original design intent was to allow this
    condition without
          > failure of the choke.
          >
          > Point of this message is to announce an AD (airworthiness
         directive) to
          > inspect and verify the type of choke used on your EC2.
    Attached to
          > this
          > message is a picture of the three types of chokes used. The
    left is
          > the
          > originally specified part. The center part is an acceptable
         substitute
          > part. The right hand part is the unacceptable choke. If you
    have this
          > part, do not fly the aircraft until it has been replaced. In
    addition
          > to the visual difference, you can determine which part by
         measuring the
          > resistance. The bad part has a resistance over 10 ohms. The
    correct
          > parts are much lower in resistance.
          >
          > We will replace the part for you for no charge except shipping
         cost as
          > specified in the warranty. This is a simple through-hole
    soldered
         part
          > that is relatively easy to replace. If you are qualified to
    replace
          > the
          > part yourself, we will send the correct part at no cost.
          >
          > Tracy Crook
          > Real World Solutions Inc.



         Tracy, for the record, I have the original choke. Jerry



    Tracy:   Where is this choke located? What do I need to do--do I pull
    the cover off?  How do I  inspect my EC-2?  The picture shows which
    choke(simply a resistor??) is correct, & which is wrong, but:  where do
    I look; why measure their resistance if I can visually inspect?  If I
    measure the resistance, must I disconnect any power source; what about
    capacitors; diodes;retained charges; static electricity; etc... please
    explain precisely to us non-EEs!
    Tomorrow I am doing fast taxi testing;   maybe first flight.
                                                                        John
    Andrich

    Turbo-rotary Long-EZ

    Camarillo, Ca


Sorry, that was an oversight in my near panic to get the word out.  Here
is a photo (courtesy of Dave Leonard).

Tracy