Twisted: Week 214 - Flap drive and engine start (attempt)

Hours to date: 1984.75

Another couple of weeks of (mostly) backwards progress I'm afraid.

I figured out that the throttle cable that was supplied with the kit was a solid wire type and more suited to a choke than a throttle. So I bought a new cable and installed that - the action was now much smoother and not catching on anything but when I looked up to the engine I found that the full travel of the lever in the cockpit was only giving 0 to 40% throttle on the engine.

So this will need a major mod to fix. I will have to remove the existing lever and put in a vernier type throttle - the same set up as Pete has. This will need a mounting point and cover built into the side of the cockpit. Joy!

When testing the fuel pumps one worked perfectly and when I tried the other one it worked for about one second before stopping and making a 'pop' noise. So one fuel pump has failed - I will see about getting a replacement sent.

Then I went to try an engine start for the first time and despite giving it a good crank it did not want to fire up.

As there was no popping or any un-burnt fuel in the exhaust pipe then this led me to believe that it was the ECU that was not working. The ECU controls both the ignition and fuel injectors.

After a bit of fault finding I found that the fuse on the power supply to the ECU was blown. Upon replacing it and turning it on again the fuse blew again within one second so there is some fault in the wiring to do with the ECU. I've ordered a circuit testing device that is non invasive, that is, it can detect current through the insulation of the wire so no need to butcher my wiring to find the fault (we hope).

I also found a couple of small fuel leaks from the fuel pumps - where they connect to the joining tube and fine filter. The copper washers there obviously were not done up tight enough. I will sort that out when I replace the faulty fuel pump. Good to find these things before bonding on that lower fuselage panel methinks.

Let's end on a positive note shall we!?

I managed to bond in the plastic bearings for the flap drive and then rivet everything together. All works good! As I said last post I would not want to do this job after the fuselage base had been bonded on.

The order to do this in (after the plastic bearings are bonded in) is:

1. Put wings on and align flaps to fuse with clamps - making sure that the flap pins are fully in the plastic bearings on the drive ends.

2. Rivet on the loose bearing end - access will only allow a couple of rivets at this stage but that is okay for the moment.

3. Once you are happy with everything drill and rivet the motor arm - again 2 rivets is enough here.

4. Take the clamps off and fire up the electrics. Test the flaps for operation.

5. If all is well mark the tube and arm position with a pen (not absolutely necessary as you have the holes already drilled to line it up again) then drill out the 2 rivets previously put in the arm - so the tube can now be rotated 360 degrees.

6. Rotate the tube in stages (by hand) to complete the drilling and riveting of the loose bearing end.

7. Align the tube again with the motor arm to your mark (and holes that were already drilled). Rivet those two holes and complete the rest of the drilling and riveting.

8. You're done - go have a beer.

As you will have noted I pre-drilled both the motor arm and loose bearing end to make life easier.

Hopefully I will have a more productive next few weeks!