Foxcon Terrier - Re-power

Repowering a Foxcon with a ULpower UL 350iS engine.

ZK-ENN was constructed in 2009 and entered the Microlight register on 14 Apr 2010.
Originally the airframe was powered by a Subaru EA81 100hp automotive engine. The engine was connected to a Power Fin propeller via a belt driven reduction gearset.  As the owner had lost all confidence regarding the reliability of this configuration, Mr Belfield sort consultation with AVserv Ltd to decide on a suitable alternative engine and propeller.  After discussing various options a UL Power Aero Engine model UL350iS was agreed upon. This engine is fuel injected and has electronic ignition all controlled via Uls EMS (Engine Management System) alone with a Whirlwind propeller.

The aircraft was delivered to AVserv Ltd workshop at Tauranga Airport. Before removing the existing power plant, the aircraft was placed on scales and set up in the flying attitude as per the manufacturer’s recommendations. The aircraft was surveyed to determine a weight and balance benchmark along with identifying its airframe thrust line in this configuration.

Tear Down

The following components were removed from the airframe:

  • Subaru EA81 aero conversion power plant with Power Fin propeller.
  • Engine mount along with fuel, water and oil assemblies.
  • 5/16 OD nylon fuel lines along with stop valves and fuel tank sight gauge tubes.
  • Airframe electrical system supporting both airframe and power plant.
  • Coms and transponder assemblies, along with all electrical, antenna, voice and data networks.


 A new engine mount was constructed following the basic design of the original frame constructed by the manufacturer. Upgrade mods were 0.75in tube instead of 0.625 tube, two more cross bracing tubes running from the firewall mounts to engine attachment mounts. Engine attachment mounts are as per UL Aero recommendations.

Installation of UL Aero engine. The engine along with fuel and oil systems were installed as per manufactures instruction manual and specifications.

Whirlwind GA-UL350-3B series ground adjustable propeller and spinner.

10 litre supply/collector fuel tank. This feeds the fuel injection pumps and collect the unused fuel returning from the injection system. Both wing tanks feed directly into this collector tank via 3/8 Alum tubing. The pilot can choose to either feed from one wing tank at a time or both wing tanks while in flight.

Electrical network. As this new power plant requires a more elaborate support network, it was decided to remove all existing wiring systems and start from scratch. This included all the automotive switches, fuses and dials. A new flight panel was designed and manufactured to fit back into the existing fuselage consol. The new network is constructed using gold contact switches to supply power to the computers and relays, LED warning lights, Mil Spec Fuses and Mil Spec wire.

Xcom transceiver. Reused existing transceiver coupled to new wiring harness along with new RG 400 antenna cable.

MGL Extreme EFIS along with UL RDAC reader. The reader interprets the data sent from the UL computer and displays it on the MGL screen. Install ASI, AI, VSI manual flight dials.

Trig TT22 and Trig TN72 ADS-B transponder.

Install new pitot and static lines from pick up receptacle on LH wing to flight panel.

Removed existing self-tapping screws securing pilot and passenger seats to airframe. Installed AN bolts and nuts that now pass though fuselage former.

Design and manufacture top and bottom engine cowlings and cooling baffles.

Post Installation

On completion of the above work, the following post installation inspections were carried out.

Returned to scales for re-surveying to confirm weight and balance envelope.

Fuel flow tested at inlet of high pressure pumps carried out.  (190 Ltrs P/H) Burn rate based on 24 Ltrs per hour at full power.

100 Hour UL Aero Engine and Foxcon inspections.

SAC annual validation inspection.

ADS-B Installation inspection.

24 Month avionic inspection.

Engine run up tests.


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