Pilots Log

The Ancillaries

The two oil coolers are plumed in series, with the hottest oil going to the front first. Rich Goodwin Airshows have the original certified S2 has its oils cooler mounted on the engine mount with a duct from the rear left baffle. This was not part of the original G-EWIZ so I had to fabricate a bracket and decided to mount it on the firewall and make a fiberglass duct from the rear baffle. See Photos, but basically made a nice shape out of insulation foam and then covered it in glass cloth using the cooler as a mould When it had all set hack the foam away, which gave Colin Hales, my inspector great pleasure. The front oil cooler is so tight in the cowling the mounting ears have to be reduced in size to a minimum. The Airflow Performance fuel injection metering body takes its air from a Ram air trumpet which is still work in progress. There is no alternate air. The inlet has a ¼ inch stand-off behind the front baffle. In the event of a blockage air can be drawn from inside the cowl. This is fairly standard on modern Aerobatic aircraft. I was a bit concerned that there should be some sort of grill over the inlet to keep out the bigger bits. My partner Sarah used to have a very nice steel colander in the kitchen. It seemed the perfect grill! I first layed up a band of carbon on the rim of the inlet trumpet. I had to cut it off. Re-glue it back together and then shape the mesh over the front in an eye pleasing shape. I used safety wire to hold it all together and then flox and more fiberglass tape. The finished product could almost be out of a K&N box. I had read in various places that it’s no bad thing to offset the air inlet trumpet to the right putting it more perpendicular to the airflow through the prop. I had no firm evidence but thought I would give it a go anyway. I have designed the inlet to screw onto the front baffle so I can experiment with different shapes later. The grill is also removable in case it makes a power difference. With all the baffling and rubber in place the cowl still fitted, but it is all a tight squeeze. Any way, it’s all been working well in USA so I see no reason why there should be any issues with the installation. I decided not to paint the cowl until after the test flights.. I was pleased when I received the JPI instrument, beautifully engineered. Now all the wiring was about to be done in a couple of days I was even more pleased. With this electronic instrument so much of the plumbing had gone from the instrument panel. It looks  there are a lot of wires, but it only took me about 8 hours to connect them all up. 6 EGT, 6 CHT pairs for of thermocouple wired. Oil T thermocouple. Oil Pressure and Fuel Pressure transducers. OAT thermocouple. RPM sensor and Fuel Flow Transducer. The pressure transducers are mounted on the engine mount with a short hose and restrictor in case of leaks. All the CHT thermocouples are bayonet fitted in each cylinder and the EGT probes require 1/8 inch hole drilled in each exhaust stack 3 inches from the cylinder. As I connected each sensor the JPI reconfigures itself for the new sensor. All the EGT’s and CHT’s read within one degree of each other and the other temperature sensors. It was recommended to leave all the wires long so sensors can be swapped when fault finding. All the alarm limits can be set but for the moment I left factory settings which are Lycoming limits. Additional sensors on the 740 are Amps, fuel flow, Hobbs and fuel quantity channels. Programming is all very user friendly and a variety of defaults can be set up. It can be set to lean rich of peak or Lean to Lean of peak when setting cruise modes. Hopefully not too often! Mounting the Injector body was very tight and took a bit of consideration on how to get all the cables in the right place. New brackets had to be fabricated and all the throws had to be adjusted in accordance with the manual. The fuel plumbing went back in pretty much as it came out although tanks had been repaired. Plumbing on the firewall required new hose set ups for the flow transducer and fuel pressure. With the introduction of the new skydynamics Maxi Sump and two oil coolers there is general spaghetti of new hoses. I get all my hoses from AN plumbing in USA. (Earls Stuff) All high quality steel braided with speed flow fittings so hoses can be made up with a spanner and a vice. Very good stuff, but not cheap. Where possible I secure hoses with “P” clips, otherwise tie-wraps. Despite the number of hoses it all came out reasonably neat. On the new Skdynamics exhaust there is a male -10 fitting to take the over flow oil from the christen oil/air separator. There are also two NPT fittings welded on the sides for the all important smoke oil. On the Eagle we just drilled small holes to get the flow rate correct. Richard Welch, fellow Aerobatic Pitts pilot had done quite a lot of experimenting on his smoke set up so I decided to follow what he had done. Basically it involved drilling an M 5 bolt, just short of its internal end. Cut head cut off and tap it into the end of NPT fitting. Cut a slot in it at 45 degrees and aim against the exhaust flow. It sticks out about an inch into the pipe. We will see how it all works, but thanks to Rich who did the experimenting work on it. Part of commissioning the Airflow performance Injector involves flushing the fuel system through, firstly to the main fuel filter and then through the injector body, flow divider and nozzle lines. This is done with the lines disconnected from the injectors and small cups to catch the fuel. All worked fine. The Engine has one Bendix Mag on the Left and a shower of sparks set up for starting. The right Mag is replaced with Lightspeed Electronic ignition and a Hall Effect Mini Sensor with magnet ring on the flywheel. This is as was originally fitted. The switching on the panel has been wired with left, right Mag switches and a starter button. I have wired in the following logic so the engine can be started on left, right or both mags. The starter only engages with either the left, right or Both Mag switches on. The Shower of Sparks vibrator only operates when the left Mag is on and the starter is engaged. Hope it starts OK. Soon. Prior to starting the overhauled engine it is important to get good oil pressure. This took a while to work out! There are a lot of hoses to fill and until the pump is primed oil is not going anywhere. Tips like loosening the oil pressure pick up did not make any difference. Eventually I had to back fill the pipe to the oil cooler and turn the engine over backwards the get the oil into the pump. As soon as I did this and spun it up without the plugs, the oil pressure indicated on the JPI. There is a service Bulletin on breaking in the engine. Basically a short 1000 RPM ground run to check all the indications, then cowl off and leak check. A quick power check and then go and fly at minimum 75% and 65% power for a couple of hours. Looking forward to it and now waiting for the permit to test to come back. Soon I hope as I actually have two Air Show bookings in 2 week’s time. Guess what I will be doing on the airt test. Will post a brief test report when it has all been sorted..