It's been quite some time since I last posted I know but I have actually been doing a fair bit of flying lately. I have been doing a few Aero's here and there locally and have been formation flying with another club member also with his RV7.
I did have a big mishap in that time though which was a Rotec TBI failure in flight that almost had me making an emergency landing in a paddock! I was lucky is all I can say. Lucky that I had read a bit about what to do if they fail and also that I had an emergency fuel pump installed into the system in case of this exact situation.
I look back now on the event and can see the warning signs from that flight. If I had paid better attention I would have turned back and also have saved my engine from major works required. I had been trialing Premium Unleaded and it also was a hot day. I had noticed from other test flights with Mogas that the Egt's tend to run a bit hotter and the engine actually runs a little leaner with the same settings just different fuel. However I had also ignored the fact that, primarily over the last few flights, they had actually been starting to rise and I hadn't really noticed. It was a long term thing that, looking over the flight data from a few flights before, I now notice. The TBI was starting to block up and I was unaware.
So long story short I was travelling at about 2500ft on a very hot day, 2 x pob when the EGT's started to rise and of course along with the CHT's. As they passed 400f at full rich it also started to detonate badly. I switched the fuel pump on but no change. I started to then look for a paddock as it was only a matter of time I knew before the engine would quit. I pulled the fuel over ride and it started to just force feed it fuel at about 48 litres hour. It did run again, that was relieving, and I pulled basically full lean. It was down to about 35 litres hour but running again and able to just climb. In that short time I was down to about 1000ft and was about to declare a mayday on the emergency channel but as it was now climbing again and I made a bee line for home.
We did make it back to base but the motor had roasted 2 x exhaust valves and 1 x rear cylinder was toast. We both had a beer on landing and thanked whoever that we made it home.
Anyway not to be too disheartened I grudgingly switched back to the Aerocarb after replacing two heads and the cylinder and was flying again in no time.
That was the day that I decided to go through the process of an Engine conversion. I briefly considered a Jabiru 3300 but really, if I was honest with myself, I wanted a Rotax 912 through and through.
I don't want anyone to think though that I didn't trust the Turbo Aerovee, really it's a testament as to how it held up yet still got me home after being absolutely roasted by the fuel issue from the Rotec Tbi. I saw temps of over 520f+ and it was still running strong. It was down badly on compression on 3 x cylinders as we limped home but with the turbo still going strong we barely noticed a power drop once I could get fuel back to the engine via the over rides.
I think the decision was mostly made as I have just had a guts full of working on the engine. I have lost count of how many engine mounts I had changed due to the mount being incorrectly made from factory. They are going okay now (the engine mounts) but I think the Tbi failing was the last straw.
Since the engine rebuild I have done, at a guess, around 20 + hours. The last flight I had though was a ripper and couldn't have ended on a better high. Our Aeroclub went out for a fly away lunch with 7x planes and 14 x people. A great day was had by all and the Turbo Aerovee went like a song. I think I averaged about 130 kts each way as I was pushing it quite hard to try to beat some other planes that I got the jump on, although a Rv7 and a Cessna 400 beat me back, but hey, I gave it a try :)
I will miss the distinct sound the Aerovee makes and I think so will a few others in my Aeroclub. I feel the Turbo really makes them sing and I feel a bit disheartened I have given up just as I think I have gotten on top of it, but them the breaks. Time for a new chapter.
