Saturday, 13 April 2013

Annual time

April is annual time for G-JONL. The Permit to Fly expires on 5th May each year and so I start working on her ready for the annual inspection early in  April.

My Sportcruiser is three years old now and has done around 220 flying hours. For the first time there were a few minor faults that had to be sorted out in addition to the standard annual maintenance work.

The first problem was that the port exhaust gas temperature (EGT) sensor suddenly stopped working a few weeks ago. Not really a huge problem but the odd values it was registering (100°C one moment, 1100°C the next) were a bit disconcerting, even though I knew there was nothing actually wrong with the engine.

Well it turned out that the sensor had gone open circuit and the Dynon engine management system was greatly confused by this and displayed essentially random temperature data as a result. The problem was easily fixed by fitting a new sensor. I got a second spare, in case the other side decides to fail next.

Still on the port side of the aircraft, the port fuel level indication has always been a bit unreliable. Again this wasn't really a big problem, as I fly 30 minutes per side, so fuel quantities are always more or less the same in each wing. The starboard fuel gauge worked perfectly, so no big deal.

I decided I would try to fix it. Tests suggested that the problem was in the vicinity of the wing root, where there is a connector to simplify removal of the wing. With the wing fairing removed, it turned out to be just possible to get this connector out through the gap between the wing and the fuselage. Sure enough the connector was at fault and was quickly replaced.

Unfortunately, this didn't fix the problem! Much head scratching. Eventually I realised that the next connector in the line,  where I had been measuring the circuit was itself at fault. This was self inflicted - by poking the test meter probe into the connector I had forced the socket pins open and there was no longer a reliable connection. A little work with a tiny watchmaker's screwdriver got the sockets back in good shape and a reliable connection ensued.

It was now time to calibrate the fuel level sensor by slowly adding known amounts of fuel and noting sensor values. Time consuming but straightforward enough. Result: a reliable port fuel tank level indication on the D120 EMS display.

Finally, taking the main landing gear wheel spats off to inspect the landing gear I was surprised to find a broken spat mounting bracket on the starboard side. Apparently this is a known problem and breakage is "just a matter of time". The solution is to weld some gussets into the bends, so I shall get that done on both sides as soon as possible. Meanwhile I can fly without the spats fitted, with only a small reduction in airspeed.

The remainder of the inspection went well and my ever helpful inspector signed everything off yesterday. I completed the test flight yesterday afternoon and all the paperwork is now on its way to the LAA for permit renewal.

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