Technicals

SX300 Group Parts Pool Participation Policies This Parts Pool program is intended to help solve some of the critical parts problems that exist and those that will worsen as our aircraft age. This approach should help Doug maintain a modest supply of hard to find parts, speciality parts and parts that have to be purchased in quantities, while eliminating most accounts receivable issues and avoid taking advantage of anyone. Parts Pool policy will be reviewed annually by the SX300 Group and changes made as required.

SX300 Bulletin May 2, 2006 Revised March 17, 2009 This bulletin is to advise all Sweringen SX300 owners of the potential for Main Landing Gear Trunion failure. To prevent possible structural damage and bodily harm, The SX300 Group and its Technical Adviser is recommending that all owners, particularly those with flying airplanes, replace the original Airight Main Landing Gear Trunions p/n 67001-1 &-2 with a new modified part as soon as possible.

New high performance Hartzell Prop! Available now! I’m pleased to announce the availability of an improved Scimitar style prop from Hartzell. Flight test was performed in Nov 2011 with Mike Smith’s SX300 , IO-580, with 10 to 1 pistons. It basically is a Lancair Legacy blade with an improved hub that fits our aircraft. The spinner backplate requires some modification [see photos below]. The weight is approx 80 lbs. The diameter is full 75 inches [legacy blades have 1 1/2 inch cut from each tip for their ground clearance].

Electric Aileron Trim System Installation of the Ray Allen Company, Inc. electric servo, connected to the servo tab on the aileron, is a worthwhile modification. You can eliminate the existing springs and cable system, which reduces the control friction and gives the ailerons a lighter feel. The system can be installed during construction or on a finished aircraft. If you are interested in this modification, you can contact Doug Poli for detailed drawings of installation or complete kits.

Oil Cooler Air Flow Improvement Modification Route engine air box hose to blind corner of oil cooler instead of heater shroud to increase air flow to oil cooler for lower oil temperatures. This modification will lower oil temperature 12 to 15 degrees. Add elbow below oil cooler and route hose to heater shroud to improve heater efficiency. Fig 1. Oil cooler <--- FWD Looking down on oil cooler mount. (no cooler installed yet) Fig 2.

Additional Fresh Air System This system takes air from the engine cooling air box and directs it into the cockpit. The air at the air box nipple location is ambient temperature and is unrestricted ram air so there is a lot of it. The valve mounted on the firewall controls the air flow and also serves as a shut-off valve. The valve should be stainless steel for fire protection. For maximum efficiency, a 4" NACA Duct (scoop) can be installed backwards in the belly towards the tail to create a flow thru ventilation effect to handle the additional air.

Cooling Baffles For Cylinder No. 3 and Cylinder No. 4 Cylinder #3 Cooling Baffle Cylinders #3 and #4 tend to run hotter than the other cylinders because air is not forced down and around the cylinder. A simple formed baffle can be attached to the top air box cover to direct air around the cylinders. This works well and is simple to do. See photo above and sketch below. Sketch submitted by Mark Bratton.