fbpx

 

I am new to Rotax engines and have my 915iS installation complete and nearly ready for first engine start.  I am some time away yet from getting my airplane into the air, but have begun studying the operation of the engine in more detail.

The Operators manual is fairly clear on the starting procedure and pre takeoff checks, but it is a little tedious to read through and some areas aren’t 100% clear.  For example, the lane checks appear to be performed at 2500 RPM.  The wastegate and PCV check specifies full throttle, but there is a note saying this check can be combined with the lane checks.  Then there is the fuel pump checks at 2000 RPM.  And I forgot the full throttle performance check before the lane checks. Not sure how you combine the lane and PCV checks given that they occur at vastly different RPMS.

I was hoping to find a video here going through the full ground test, but have yet to find one.  It appears to me that the sequence is basically this:

1. Warm up the engine.

2. Do a short WOT test to ensure the engine will rev to max static RPM.

3. Throttle to 2500 RPM for the lane checks.

4. Throttle to wide open for the wastegate and PCV check.

5. Throttle back to 2000 for fuel pump checks.

6. Then back to idle until takeoff.

Does this sound about right?

If anyone is aware of a good video that covers this in real-time, please pass it along.

  • Re: Pre takeoff checks

    by » 3 weeks ago


    I’ve got a Rotax 915 iS in my Sling TSi.  I start on main fuel pump with about 40% throttle.  After the engine turns over, I check for lane lights out within 5 seconds, oil pressure above mins within 10 seconds, fuel pressure in normal range 42-46 psi.  Then push the throttle up to approx. 2500 rpm, and watch you amp meter,  you should see it go from a negative value, indicating battery discharge, to a positive value, indicating battery is charging.  The Rotax Fuse Box/Regulator/Rectifier system will switch the electrical output from GEN A to run the engine and GEN B to the battery bus and avionics bus to charge the battery and power avionics.  Leave the RPM at 2500 until oil temp reaches 120 deg F, then you can pull it back to idle.  Once at the run-up area, I run the RPM up to 4000 to check both Lanes A/B and both fuel pumps.  I’ve got an Airmaster Constant Speed Prop, so I also do the prop checks at 4000.  Then, if all engine instruments are in the green and pre-takeoff checklists are complete, you should be ready to go.  Hope this helps.  Sling has a couple of You-Tube videos out that cover the run-up checks.


  • Re: Pre takeoff checks

    by » 3 weeks ago


    Thanks, Bryan. I will search for the Sling videos.  So, it sounds like you don’t do the PCV test that Rotax lists in the manual.  I assume you take off with both fuel pumps on and then turn one off at altitude, correct?


You do not have permissions to reply to this topic.