R22 Rotor Tach Flicking below 80%
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mrecht
Member Since : 2010
Posts(3)
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R22 Rotor Tach Flicking below 80%

10-07-2013 04:17:32

Our rotor tach started flicking up and down when below 80%. Above 80% it reads normally as does the engine tach. The governor works normally.

Is it likely to be the gauge ($3000) or the Hall effect sender ($100) ?

Thanks

Mark...

Replies

MVH-DOM
Member Since : 2013
Posts(63)
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10-07-2013 10:17:31
Try swapping the plugs on the hall effect sender, I know its a bit of a bugger to get to, but both hall effects sender are set to the same gap.  Then you will know for sure.  The governor has nothing to do with the hall effect senders and does not come online till above 80% anyway.
mrecht
Member Since : 2010
Posts(3)
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10-08-2013 04:48:27
Thanks - good suggestion, will give it a try.

So does the governor use the magneto feed that also drives the engine tach ?
MVH-DOM
Member Since : 2013
Posts(63)
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10-08-2013 07:50:29
Yes, the R/H magneto on the L/H side of the machine, has a set of Tach points in it.  The governor and the engine tach share the same signal.  However, the governor needs a very "clean" signal to operate correctly, the tach doesn't really care too much.  If your tach points are dirty, pitted or not adjusted correctly, the governor may overspeed the engine or not work at all (have seen both happen in R44's).  I have had brand new magnetos from Aviall not provide a clean enough signal for the governor and when switched on, nothing happened.  That is when I also learned that regardless of the 44 (12V or 28V) the governor motor is 12 volts.  A call to RHC confirmed this.  Sorry to ramble on, I hope this all helps.
mrecht
Member Since : 2010
Posts(3)
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10-09-2013 02:23:12
Thanks for the info !