RPM Drop in 912ULS

All

Mogas in Colombia (spell with o not u please) has no seasonal fuels.  Remember they are only a short way north of the equator and even high in the mountains don't get the cold as in North America or Europe.  As we know the AirCam is a twin engine, it it was vapor pressure the other engine should have had the same symptoms i would expect.  Last I was down there they do not have Ethanol added to the fuels.  

Cheers

That's right—ColOmbia (with o, not u) doesn't experience those temperature changes. I believe the last time you were here was pre-pandemic, and since 2021, they’ve started adding ethanol.

Here’s an update for everyone: Before the latest incident, we inspected the pipes, tanks, spark plugs, and spark plug ends as suggested here (all were within the resistance range; see attached picture). We also swapped the ignition modules between engines to rule out the unlikely possibility of a faulty module. I’ve conducted two test flights, the latest being a one-hour flight yesterday, but I couldn’t replicate the issue.

If the issue reappears, as suggested here and by Dean at Lockwood, the next step will be to swap the carburetors to see if the problem transfers to the right engine.

Thanks all for the valuable advice!

Francisco

(Adding a picture of the Aircam)

Thanks Carlos!  Yes, I do recognize that !

Done!

Sean Griffin wrote:

Sounds  like an intermittent fuel supply problem.  As you have blown out the fuel lines, what of the tank ? 😈

As above - Have you checked the fuel tanks(s) for contaminants???

Pickled insects, bits of leaf, paint flakes , etc can cause an intermittent partial/total blockage .😈