Saturday 20 August 2016

Fuel System Installation #3 - Vents and Siphon Valve

Been working on the fuel system this week. All the fuel lines, vent lines and drain lines are done except the ones that will connect to the wing tank.

Here's an example of two vent lines that I finished today. I used tie-wraps and scrap pieces of rubber tubing as spacers between the tubes:


These two lines were originally passing just beside the fuel tank without going through the aluminium bracket. They were so long that I had to bend them every time I needed to remove/reinstall. I therefore decided to add bulkhead fittings (see top of the picture above) I found cutting the tubes in two halves is much easier to work with and also more convenient if I ever need to remove my main tank again.

Another new feature I installed is the siphon valve in the vent interconnect line between the header tank and main tank (see diagram here). It's a great idea suggested by my friend Mark Wood down in Wichita in order to avoid too much fuel being transferred back into the main tank while inverted. It is quite simple, avoids buying an expensive check valve and allows higher vent flow than a typical vented check valve. It is made by assembling two AN816-4D fittings in a AN910-1D NPT coupling with a ball in the middle. The only modification to be made is a castle shape on the bottom fitting to allow air to flow in the upright position. This is reasonably easy to do with a file. See below:


Here's what it looks like once installed on the airplane. Assembly to be secured with either Adel clamps or Koroseal lacing.


Next task is to start reconnecting wires. Stay tuned!

Sunday 7 August 2016

Throttle and Mixture cables

Ran out of fittings to continue the fuel system installation so I decided to work on installing the throttle and mixture cables. My cables used to be secured with loose tie wraps, which obviously I didn't like. I therefore installed Adel clamps like this on two places. This got me a nice, tight installation:



I found these Adel clamp installation pliers at Oshkosh last year. They came with a sharp stick to line up the clamps together. They work quite well and save me some time:


The old firewall installation was grommets + a huge blob of RTV sealant. While the engine was still under the crane, I planned to replace that with two Cable Safe II bulkhead fittings. The advantage of these fittings is that they split into two halves so that you can install them on cables that already have crimped terminals on both ends. Here is the final result:



Both cables were manufactured by ACS. when I removed them last year, I found that all grommets on them were dry and cracked. I was pleased to see that Spruce had them for sale (see here). I therefore replaced all four of them (one on each end):



I was quite happy once the cables were all secure, free of interference and chafing. It took my a few iterations to make sure I had the full travel and that the controls in the cockpit were where I wanted them.

Fuel System Installation #2 - Header Tank

Got my flop tube back from my friend Scott. It now has a total OD of 0.900" which allows it to get in my header tank!



It took some time to reinstall the header tank back in its right place, but it's good to have it back:


I replaced the old Tygon tube by this yellow one which is fuel resistant (ordered it from US plastic).



The GMAC distraction ; )


Been a while since my last post. Went to help the team at the Green Mountain aerobatic contest in mid July. Two of my friends came back with pieces of wood in the baggage compartment! Congrats to Philippe and Luc; you've done an awesome job!

Philippe with his Superb D:

Luc receiving his prize:

My friend François helped as a judge:


It was great to see airplanes that fly. It gave me some motivation to continue my project!