Moments after takeoff Saturday I smelled burning plastic, like one or two deep breaths of it, as I was climbing out. All indicators were normal, no alarms or tripped breakers, nothing, so I just assumed it was environmental odor (I live in a desperately ugly place and you depart over slums) and flew on. At no point did anything seem amiss in the remaining 72 minutes of flight.
I still wasn't happy with this (non)incident, so this afternoon I pulled the cowl and discovered the problem--you can see the photos. The connector has melted, bigtime. Scraping the plastic reproduced the odor. As you can see, the wires connect to the voltage regulator--I believe that these are connect to G G on the left side of the Ducati regulator and Rotax diagram (Fig 67 in the 1 may 2009 install manual) identifies these as "integrated generator." (Though in my IRMT notes I have written "stator" by this block.)
I've attached the diagnostics from the electrical system, showing the data for the burned connector and the data for a similar time interval in a "normal" situation. The first voltage peak (blue traces) is runup. You can see in the burned connector scenario there is a voltage drop.
Why did this happen? I think bad insulation--look at the photos.
If this is something as key as the electrical connection between the generator and the VR, why was there no sign of this in any flight instrumentation--I mean it's like nothing happened. I can't figure this one out. Battery charged fine. Why didn't I just drop out the sky, or at least have only battery power to emergency return to the strip?
Finally for the fix: I'm just going to cut out the damaged areas, and reconnect everything with butt connectors; don't have any amphenol connectors of sufficient pitch on hand. Obviously static test followed by very conservative test flight.
Comments appreciated!
I still wasn't happy with this (non)incident, so this afternoon I pulled the cowl and discovered the problem--you can see the photos. The connector has melted, bigtime. Scraping the plastic reproduced the odor. As you can see, the wires connect to the voltage regulator--I believe that these are connect to G G on the left side of the Ducati regulator and Rotax diagram (Fig 67 in the 1 may 2009 install manual) identifies these as "integrated generator." (Though in my IRMT notes I have written "stator" by this block.)
I've attached the diagnostics from the electrical system, showing the data for the burned connector and the data for a similar time interval in a "normal" situation. The first voltage peak (blue traces) is runup. You can see in the burned connector scenario there is a voltage drop.
Why did this happen? I think bad insulation--look at the photos.
If this is something as key as the electrical connection between the generator and the VR, why was there no sign of this in any flight instrumentation--I mean it's like nothing happened. I can't figure this one out. Battery charged fine. Why didn't I just drop out the sky, or at least have only battery power to emergency return to the strip?
Finally for the fix: I'm just going to cut out the damaged areas, and reconnect everything with butt connectors; don't have any amphenol connectors of sufficient pitch on hand. Obviously static test followed by very conservative test flight.
Comments appreciated!
IMG_0488.jpg (You do not have access to download this file.)
IMG_0489.jpg (You do not have access to download this file.)
IMG_0490.jpg (You do not have access to download this file.)
IMG_0491.jpg (You do not have access to download this file.)
Electricalsystemdata-burned.png (You do not have access to download this file.)
Electricalsystemsata--Normal.png (You do not have access to download this file.)
