On Wed, 22 Jun 2011 18:22:11 -0700, Casey Barker <[email protected]> wrote: Non-text part: multipart/mixed Non-text part: multipart/alternative > Hi folks, > > I've been looking over the Telemetrum schematic and trying to figure out > whether the header power switch (v_lipo/v_charge) meets the NAR Level 3 > requirement to "physically break the connection between a pyrotechnic system > and its power source" to safe the charges externally. My limited EE > background says there's no way the output transistors are going to pass > current without the switch turned on, but I don't know how the NAR feels > about this. Any thoughts?
This is something you should discuss with your L3CC member, but you can examine the circuitry of the TeleMetrum and note that with the power switch in the OFF position, there is no possible connection between the battery and the ejection charges. > I was hoping I could get away with just the one switch for the Telemetrum, > plus whatever switch(es) my (heterogeneous) backup needs. Otherwise, I can > see my avionics bay quickly turning into a bit of a rat's nest. The existing power switch on TeleMetrum meets my reading of the NAR L3 certification requirements. However, your L3CC may want to see a separate switch in-line with the ejection charges themselves as that is a fairly common practice in L3 cert airframes. I used separate power and arm switches in my L3 airframe, however one of the flight computers in that airframe was of a closed design and so I couldn't verify that the power switch would be sufficient. If you do end up using a separate arming switch, at least you only need one; the schematic will show that the ejection charge connections share a common connection on the board. -- [email protected]
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