912 S3 partial power loss after Takeoff

Hello Pascal

From what you say I would also guess perhaps vapor lock with the MOGAS.  Auto fuels have variable RVP, reid vapor pressure.  It is rather difficult to check what level of RVP you have so best guess might be you are getting some winter fuel.  Spring flying is the real risky area as a lot of fuel supplies are still in change over from winter blends that have high RVP, more vaporization, than sumer blends.  The common practice from the fuel producer/supplier is to sell fuel with a lot of Butane in it to increase vapor for cold weather starting.  Summer fuels are very low RVP and usually cost more than winter fuel. Check your fuel supplier and ask when they changed blends.  if people are buying winter blend in the spring it can create a lot of issues.  If your switch to AVGAS has solved this issue then you have your answer and need look no more.  

A check here shows the numbers for EN228 

This requirement has been transposed into BS EN 228:2012 which specifies a summer minimum and maximum RVP of 45 - 70 kPa and winter minimum and maximum RVP of 70 - 100 kPa

Have you complied with this

Ref: IM-73-00-00

Fuel System

Sounds like Vapour lock to me, where you haven't fitted the return line with the restrictor jet:  

You may also like to consider the Vans RV-12 recommendation to install a higher capacity fuel boost pump:

 https://www.vansaircraft.com/wp-content/uploads/2018/12/Notification-2018-07-12.pdf

 

 Facet Cube40135  can be purchased on its own or in the kit Part  Number FEP12SV

Your experiencing detonation. See the latest Aquila ASB calling for new exhaust. We maintain two AT-01-100 and both engines have detonated multiple times although the club runs on AVGAS. New exhaust for less back pressure at 156/2.72 jetting cures this. 

We also installed EGT under CSTAN  

https://aquila-aviation.de/wp-content/uploads/2023/02/SB_AT01_041_A01_exhaust_912_O44mm.pdf

Rotax Wizard wrote:

Hello Pascal

From what you say I would also guess perhaps vapor lock with the MOGAS.  Auto fuels have variable RVP, reid vapor pressure.  It is rather difficult to check what level of RVP you have so best guess might be you are getting some winter fuel.  Spring flying is the real risky area as a lot of fuel supplies are still in change over from winter blends that have high RVP, more vaporization, than sumer blends.  The common practice from the fuel producer/supplier is to sell fuel with a lot of Butane in it to increase vapor for cold weather starting.  Summer fuels are very low RVP and usually cost more than winter fuel. Check your fuel supplier and ask when they changed blends.  if people are buying winter blend in the spring it can create a lot of issues.  If your switch to AVGAS has solved this issue then you have your answer and need look no more.  

A check here shows the numbers for EN228 

This requirement has been transposed into BS EN 228:2012 which specifies a summer minimum and maximum RVP of 45 - 70 kPa and winter minimum and maximum RVP of 70 - 100 kPa

indeed we also have to use winter type, but our airport is trying to minimize the amount filled up in the tank and switches back to summer mix asap it is available again... will have to check that with the airport... thx