Points for Pilots

Cooling shroud and black blast tube for voltage regulator When my friend Mel and I built the Zenith 601 HDS, N314LB, in 1995, instructions for installation of the voltage regulator--to be precise, voltage regulator/rectifier--of the Rotax 912 did not contain any information about temperature limits. Ditto for the ignition module. We first became aware of potential overheating of components by the Rotax Minute - Component Temperatures video available for subscribers of rotax-owner.com .  The video mentions a temperature limit of 176 deg F, or 80 deg C, specified by Rotax for both voltage regulator and ignition module. In our plane, ram air entering the cowl cools the ignition module.  Since that module does not generate any significant heat, and since air temperatures inside the cowl are well below the 176 deg F limit, we are not concerned about that module. A different matter is the voltage regulator. It produces significant heat, as is implied by its cooling fins. Th

Pump System with two Facet pumps and low-pressure switch In 2014, the  19-year old Rotax 912 engine of our Zenith 601HDS, N314LB, had run 1,618 hrs without any sign of wear or significant trouble, with one notable exception: The mechanical fuel pump had failed five times. Failures of the Mechanical Pump Five pump failures within 1,618 hrs is astonishingly bad performance, given that mechanical diaphragm pumps, for example in Continental or Lycoming engines, generally last beyond engine TBO without a hiccup. The pump failures were of two types.  Either the fuel pressure would drop to zero, in some cases rapidly, in others very slowly. Or the pump would leak blue-colored oil, indicating a diaphragm failure where blue avgas was mixed with oil.  That mixture would exit the cowl in front and eventually streak onto the canopy.  The shortest time between failures was 61 hrs, and the longest 729 hrs. Rotax then offered a pump of different design. It has a vent tube whe