[petersb]

For 28 hours no problems then on the last two flights I started hearing a tick, (approx three per second ) when receiving a transmission.


Tick still there on left mag but disappears on right mag only. Problem is, this is happening at 2300 rpm which should give 38 ticks per second.

Any thoughts

 

[airguy]

Very uniform speed with the ticks, or does the timing vary? If you had one spark plug wire that was leaky and jumping stray spark to something nearby, it wouldn't necessarily hit every time and might only hit about one out of twelve or so - but it would be random, not uniform.

When it disappears on the right mag only, that's a great big flashing neon sign telling you to check the left mag, wires and plugs.

 

[petersb]

Very uniform speed with the ticks, or does the timing vary? If you had one spark plug wire that was leaky and jumping stray spark to something nearby, it wouldn't necessarily hit every time and might only hit about one out of twelve or so - but it would be random, not uniform.

The tick is regular

When it disappears on the right mag only, that's a great big flashing neon sign telling you to check the left mag, wires and plugs.

Yes my thoughts also. The wiring harness is new, plugs used slightly and the mag had a 500 hour check when the engine was installed.

 

[Mike S]

What kind of radio??

Is the tick rate consistent when you go to a higher/lower frequency?? Or does it change with frequency.

Does the tick rate change with RPM??

I have a Garmin SL 40 that ticks and the rate follows the tuned frequency, not the engine RPM. Only happens after someone on freq breaks squelch. Quits when I hit the xmit button.

 

[petersb]

What kind of radio??

Is the tick rate consistent when you go to a higher/lower frequency?? Or does it change with frequency.

Does the tick rate change with RPM??

I have a Garmin SL 40 that ticks and the rate follows the tuned frequency, not the engine RPM. Only happens after someone on freq breaks squelch. Quits when I hit the xmit button.

Frequencies used so far 123.30, 119.30 and 128.85

This is a Garmin SL40, did not try change in rpm yet.

Same as you, happens after someone on frequency transmits ( breaks squelch). Is not there when I transmit.

Seems to be less when I am close to the transmitting aircraft/ airport

But why did it suddenly develop after 27 hours flying.

 

[airguy]

Frequencies used so far 123.30, 119.30 and 128.85

This is a Garmin SL40, did not try change in rpm yet.

Same as you, happens after someone on frequency transmits ( breaks squelch). Is not there when I transmit.

Seems to be less when I am close to the transmitting aircraft/ airport

But why did it suddenly develop after 27 hours flying.

Yes, that does sound like it's radio-based - so why does it quit when the right mag is selected? Coincidence?

 

[OKAV8r]

For 28 hours no problems then on the last two flights I started hearing a tick, (approx three per second ) when receiving a transmission.


Tick still there on left mag but disappears on right mag only. Problem is, this is happening at 2300 rpm which should give 38 ticks per second.

Any thoughts

If it were me, on my Lyc O-360, I would swap the sparkplugs from top to bottom and bottom to top, to effectively move the plugs fired by one mag to now be fired by the other mag. If the situation changes from one mag to the other, then you have identified it as a sparkplug. Then, switching the plugs back one cylinder at a time, with test after each, might then identify which of the sparkplugs is the culprit.
And, if the plugs are Champions, with significant time-in-service, I would be inclined to just replace them all with new Tempest plugs...

 

[RV3bpilot]

Radio noise

I had a whine from a small cooling fan so I tried a capacitor and that did help but the sound was still there. So I was advised to wire the radio to a seperate switch with a fuse in line and go straight to the battery. Now the radio is very quiet.. The battery is a very big capacitor.

 

[Neal@F14]

...snip...
And, if the plugs are Champions, with significant time-in-service, I would be inclined to just replace them all with new Tempest plugs...

You beat me to it.... I was just about to ask if his plugs were Champions

 

[Mike S]

Frequencies used so far 123.30, 119.30 and 128.85

This is a Garmin SL40, did not try change in rpm yet.

Same as you, happens after someone on frequency transmits ( breaks squelch). Is not there when I transmit.

Seems to be less when I am close to the transmitting aircraft/ airport

But why did it suddenly develop after 27 hours flying.

Peter, sounds like we may have the same issue.

Just for fun, on the next flight try tuning in something like 118, and see how fast the tick is. Then something in the 130 range, and see if the rate changes.

I talked to lots of Garmin folks about this, and no one was able to tell me what is going on. Just the same old "send it in for repair" story-----and some crazy flat rate $$ charge .

I solved the problem by selecting my SL 30 as primary radio, and keeping the 40 for use as a freq "notepad"-----or the very occasional need to monitor a third freq.

I suspect it is something inside the radio, that is generating a beat freq that is normally not audible, but some other external influence like bad ignition is causing the tick to become noticeable. i.e. the electronic widget that normally suppresses the tick is too busy fighting with some other externally generated noise, and the tick slips through. But then I sometimes have a rather active imagination

My tick did not occur until the 40 hour mark or so.

 

[petersb]

Peter, sounds like we may have the same issue.

Just for fun, on the next flight try tuning in something like 118, and see how fast the tick is. Then something in the 130 range, and see if the rate changes.

I talked to lots of Garmin folks about this, and no one was able to tell me what is going on. Just the same old "send it in for repair" story-----and some crazy flat rate $$ charge .

I solved the problem by selecting my SL 30 as primary radio, and keeping the 40 for use as a freq "notepad"-----or the very occasional need to monitor a third freq.

I suspect it is something inside the radio, that is generating a beat freq that is normally not audible, but some other external influence like bad ignition is causing the tick to become noticeable. i.e. the electronic widget that normally suppresses the tick is too busy fighting with some other externally generated noise, and the tick slips through. But then I sometimes have a rather active imagination

My tick did not occur until the 40 hour mark or so.

MIke

Sure sounds the same, including the fact it took several hour to develop.

Weather should be good tomorrow, at least -10C , so I will try frequency and rpm, changes suggested


Did you try spark plug and ignition wire changes , did switching mags stop yours ?



Peter

 

[Mike S]

MIke

Sure sounds the same, including the fact it took several hour to develop.

Weather should be good tomorrow, at least -10C , so I will try frequency and rpm, changes suggested


Did you try spark plug and ignition wire changes , did switching mags stop yours ?



Peter

Never even went the mag testing route as the problem was not RPM related.

Now due to this thread, I need to re-consider that thought. Will try to remember to do an inflight check the next time I am up.

 

[petersb]

Never even went the mag testing route as the problem was not RPM related.

Now due to this thread, I need to re-consider that thought. Will try to remember to do an inflight check the next time I am up.

Mike

Will report back tomorrow after the tests. I also have a spare SL40 so I can try out another radio and test your theory that it is SL40 generated

Peter

 

[Mike S]

Great..