Thread: Dynon D180 Hobb Counter Inacurate

My Hobbs counter has “jumped” twice since installing the D180 in my CTsw last December (I have version 4 of the firmware installed). The most recent incident was on Saturday. At the beginning of the day the Hobbs read 91.1. I then took a 0:55 flight and landed (stayed for a few hours). I then did a return flight of 1:20 so total time of 2:15. However when I viewed the Hobbs counter on the Dynon it read 95.0?

One thing I did note was that after I shut down the engine I left the Dynon on for a bit and I noticed that both the Hobbs and Trip recorder increased…the Hobbs went to 95.1 even though the engine was not running?

I have been in contact with Dynon technicians and they are stumped. I read elsewhere in this forum that the oil pressure gauge can act erratic at times when installed directly to the engine. Don't know if this could be the cause of the problem or something else.

Cheers,
Dean

Dean,

I think your best bet is to stay after Dynon. They may be stumped but tell them to get un-stumped! They are great folks and very helpful - I'd think they'd figure it out eventually.

You might also call some of the Flight Design Dealers around the US and see if they've had the problem.

Just my thoughts!

Good Luck

Roger H

Make sure you are on Hobbs time and not tach time. The tach time varies with engine rpm. The hobbs works only when the engine oil pressure is above 15 psi and records at a steady rate.

I think the latest version takes the tack time out under the Rotax configuartion.

Are you sure you have the latest version and is it set to Rotax?

Roger H

You guys are right that Dynon has it's own setup parameters for the Rotax engine and your CT should be setup for the Rotax.

On version 4 of the firmware (which is what I am running), Dynon has a setup for the Rotax 912. One of the things it does is to turn-off the Tach Timer (since apparently Rotax does not believe this to be relevant).

So, it is definitely the Hobbs counter that is occasionally "jumping".

An update...

I had a chance to go out and check my plane this weekend. And interestingly, with the engine stopped (not running) the oil pressure reads 2 bar on the D180? I discounted the lead to the oil pressure sensor and reconnected it. This had the effect of 'zeroing' the oil pressure reading on the Dynon. I then flew for an hour, landed and switched off the engine...it again showed 2 bar without the engine running.

Do you think I have a faulty oil pressure sensor or could it be something else?

I have seen that a couple of times with rotax analog gauges in two different planes. In each case just turning the electrics on and off again reset the gauge to zero.

WF

Thanks...I have tried simply turning all the electrics on then off and unfortunately it doesn't work.

For some reason I have to disconnect the lead to the oil pressure sender while the Dynon is powered.