Elec.issue

[almarsh]

Recently my Cht shows that when I turn on nav lts. Strobes my get and Cht start jumping up in big increments turn them off and goes back down what can be the issue here rky.mt. Inst monitor never had issue before 200 hrs. Help!

[pvalovich]

Please check your post - I don't understand the problem.

[vic syracuse]

Check your grounds.

Vic

[almarsh]

Ok I'll check wow where to start right!!

[airguy]

Primary suspect would be grounding between the engine block and the airframe, it needs to be grounded well or you'll see problems on the thermocouples for CHT and EGT just like you describe.

[almarsh]

Ok down to airport today all grounds check out, the interesting thing I did find out was with the engine running no nav lights on or strobes or taxi/landing lights on Cht reads normal steady to rise, but turn any light on up shoots egt very rapidly turn off back down, then switch off main buss and turn lights on all is normal. So does this tell me alternator is the issue perhaps?

Any feed back would be appreciated thanks.

[rv7charlie]

Still sounds like a grounding issue, but...

Your voltmeter tells you whether the alternator is doing its job. If it's charging, you should be seeing ~14 volts on the bus. Anything under ~13.5V is a strong indicator that the alternator isn't working. Having said that, it's unlikely that loss of alternator would cause your symptoms, unless your battery voltage is so low that it's causing abnormal functioning of your engine monitor (possibly <10.5V, depending on the instrument).

[lr172]

Originally Posted by almarsh

Recently my Cht shows that when I turn on nav lts. Strobes my get and Cht start jumping up in big increments turn them off and goes back down what can be the issue here rky.mt. Inst monitor never had issue before 200 hrs. Help!

Does the behavior happen with just Nav, Just Strobe or only with both? You should individually turn on every high draw device and see which cause the reading problem to appear. This will help to isolate whether the Eng monitor is overly sensitive (not likely given the symptoms) or if the problem is being caused by one device/circuit. As you experienced in the first 200 hours, your strobes should not be affecting the instrument. Something has happened and you'll need to do some troubleshooting / isolation to know where to look.

It is not likely your alternator. Your CHT monitor shouldn't start behaving oddly before other devices also do, if caused by low voltage. Further, if you had enough battery capacity to start the plane, low voltage wouldn't magically appear as you switch on the strobes and disappear when you turn them off.

Larry

Larry

[airguy]

Originally Posted by almarsh

Ok down to airport today all grounds check out, the interesting thing I did find out was with the engine running no nav lights on or strobes or taxi/landing lights on Cht reads normal steady to rise, but turn any light on up shoots egt very rapidly turn off back down, then switch off main buss and turn lights on all is normal. So does this tell me alternator is the issue perhaps?

Any feed back would be appreciated thanks.

Try this - with engine running, shut off the alternator so you are operating on battery power only - now repeat the lights on/off like you did earlier - what happens with the CHT/EGT?

[lr172]

Originally Posted by almarsh

Ok down to airport today all grounds check out, the interesting thing I did find out was with the engine running no nav lights on or strobes or taxi/landing lights on Cht reads normal steady to rise, but turn any light on up shoots egt very rapidly turn off back down, then switch off main buss and turn lights on all is normal. So does this tell me alternator is the issue perhaps?

Any feed back would be appreciated thanks.

How exactly do you turn your lights on with the "main buss" off? You need a bit more detail here for us to help.

Larry