Ch 23 Engine / UL520is First Start
There is so much to deal with in preparation for the first starting of the engine that I broke out a separate page from the "Initial Integration" page. In general, I'll include here the fine tuning and troubleshooting tasks associated with running the engine.
The Movie:
I'm so excited and relieved to have had a successful First Start that I'm just going to publish the movie at the top of this page. I'll then go over some of the key tasks that lead to this point as I have time to move them here from my log.
I'm so excited and relieved to have had a successful First Start that I'm just going to publish the movie at the top of this page. I'll then go over some of the key tasks that lead to this point as I have time to move them here from my log.
Fuel System Leak Testing:
With the engine essentially ready to start, it's time to check the fuel system. This is of course a little nerve wracking. I still have the plane at my house, and we are now talking real fuel. I built the strakes and sump system completely using EZPoxy with the slow hardener as widely accepted across the canard community as the most fuel resistant method. I also post cured the system on the hottest day of summer (see this strakes page) as recommended by epoxy expert Gary Hunter. I'd pressure tested everything and fixed a couple of leaks also as documented in the strakes section. Still: we're now talking flammable fuel near the house... I bought another fire extinguisher and acquainted myself with it's use. Here are the steps I took to get leak free from this point: Everything was done out in the driveway and I never brought the plane back into the garage without confirming no fuel smells and using a fan and keeping the door open for a while after any testing. Nothing is perfect, but that's the protocol I followed.
1. Replace center sump drain plug with NPT tube to plastic tube to gas can to catch any fuel draining. Poured 2 gallons of fuel in to each strake tank and let it flow down and out the main sump. Prove that I've got good gravity flow in both tanks to the central sump and drain.
2. Replace center sump drain plug and pour 2 gallons in each strake tank and look for leaks. I had one at the first flair fitting coming out of the center sump to the hose, and I could see a little drip at the hose to fuel splitter just ahead of the pre-filters. OK, removed the drain plug and held the NPT/plastic hose in the drain hole to drain the whole system. This was messy and I got fuel on my hand/arm. Not good. Better would have been to have had a valve in the exit tubing that I could just open to drain into the fuel can. Clean up mess, including a few tablespoons of fuel dripped in back seat and hell hole. I had lots of paper towels ready and they got good use. Let everything air out in driveway and go get arm cleaned up. Oh, yea. I grabbed my respirator during this clean up. Have one ready. When rested, I removed the hose from the leaking fitting and clamp area and inspected. I needed to improve the flair that I'd done on the 3/8" tubing and did so and tightened the hose clamp better than the first time. Re-tested the next day and no static leaks observed.
3. Pressurizing fuel system and testing the fuel pumps: This was the first time I'd tested the fuel pumps too, as I didn't want to run them without fuel available (instruction manual). In hindsight I could have switched them on back when I wired them up just for a second or two each to make sure the wiring works. As soon as I turned them on, I found a leak at their output banjo fitting. You can probably tell it's a pain in the butt to remove my fuel pumps from the hell hole. It was certainly a compromise I was aware of when I chose to put them there, but I did it because I wanted them on the cockpit side of the firewall, so they could function as a fuel shutoff to the engine from the safety of the cockpit side. I also wanted them operating in the more benign environment of the hell hole area below the spar compared to the engine compartment. Now I had to pay for that decision. The whole bracket comes off with 5 AN3 nuts and some maneuvering, as the output SS hose is disconnected at the fuel filter (my system). It comes out just fine once you figure out the movement sequence, and I got a little practice as you will see during this fuel system testing... OK back to the test: Inspection showed I had used a slightly larger copper seal ring than was required at one point on the banjo fitting (be aware that there are 2 sizes with the fuel system parts even though they look similar). Replaced with the correct seal ring and re-installed, and re-tested. Good at this connection, but now leaking on the output banjo fitting from the fine fuel filter (back side of firewall). At least it's OUTSIDE the cockpit now... Removed fuel filter and examined the leak area, and found that the banjo fitting I had there was oversized for the flow bolt between the filter and the fuel pressure sensor (my mistake, there are two sizes of this that come with the engine and two banjo's - I hadn't matched them together well because I didn't know there was a choice, and wasn't looking closely enough). <- lesson learned! Replaced with proper size banjo fitting and re-installed. Successful testing with both fuel pumps circulating fuel back to both tanks. What a relief!!!
With the engine essentially ready to start, it's time to check the fuel system. This is of course a little nerve wracking. I still have the plane at my house, and we are now talking real fuel. I built the strakes and sump system completely using EZPoxy with the slow hardener as widely accepted across the canard community as the most fuel resistant method. I also post cured the system on the hottest day of summer (see this strakes page) as recommended by epoxy expert Gary Hunter. I'd pressure tested everything and fixed a couple of leaks also as documented in the strakes section. Still: we're now talking flammable fuel near the house... I bought another fire extinguisher and acquainted myself with it's use. Here are the steps I took to get leak free from this point: Everything was done out in the driveway and I never brought the plane back into the garage without confirming no fuel smells and using a fan and keeping the door open for a while after any testing. Nothing is perfect, but that's the protocol I followed.
1. Replace center sump drain plug with NPT tube to plastic tube to gas can to catch any fuel draining. Poured 2 gallons of fuel in to each strake tank and let it flow down and out the main sump. Prove that I've got good gravity flow in both tanks to the central sump and drain.
2. Replace center sump drain plug and pour 2 gallons in each strake tank and look for leaks. I had one at the first flair fitting coming out of the center sump to the hose, and I could see a little drip at the hose to fuel splitter just ahead of the pre-filters. OK, removed the drain plug and held the NPT/plastic hose in the drain hole to drain the whole system. This was messy and I got fuel on my hand/arm. Not good. Better would have been to have had a valve in the exit tubing that I could just open to drain into the fuel can. Clean up mess, including a few tablespoons of fuel dripped in back seat and hell hole. I had lots of paper towels ready and they got good use. Let everything air out in driveway and go get arm cleaned up. Oh, yea. I grabbed my respirator during this clean up. Have one ready. When rested, I removed the hose from the leaking fitting and clamp area and inspected. I needed to improve the flair that I'd done on the 3/8" tubing and did so and tightened the hose clamp better than the first time. Re-tested the next day and no static leaks observed.
3. Pressurizing fuel system and testing the fuel pumps: This was the first time I'd tested the fuel pumps too, as I didn't want to run them without fuel available (instruction manual). In hindsight I could have switched them on back when I wired them up just for a second or two each to make sure the wiring works. As soon as I turned them on, I found a leak at their output banjo fitting. You can probably tell it's a pain in the butt to remove my fuel pumps from the hell hole. It was certainly a compromise I was aware of when I chose to put them there, but I did it because I wanted them on the cockpit side of the firewall, so they could function as a fuel shutoff to the engine from the safety of the cockpit side. I also wanted them operating in the more benign environment of the hell hole area below the spar compared to the engine compartment. Now I had to pay for that decision. The whole bracket comes off with 5 AN3 nuts and some maneuvering, as the output SS hose is disconnected at the fuel filter (my system). It comes out just fine once you figure out the movement sequence, and I got a little practice as you will see during this fuel system testing... OK back to the test: Inspection showed I had used a slightly larger copper seal ring than was required at one point on the banjo fitting (be aware that there are 2 sizes with the fuel system parts even though they look similar). Replaced with the correct seal ring and re-installed, and re-tested. Good at this connection, but now leaking on the output banjo fitting from the fine fuel filter (back side of firewall). At least it's OUTSIDE the cockpit now... Removed fuel filter and examined the leak area, and found that the banjo fitting I had there was oversized for the flow bolt between the filter and the fuel pressure sensor (my mistake, there are two sizes of this that come with the engine and two banjo's - I hadn't matched them together well because I didn't know there was a choice, and wasn't looking closely enough). <- lesson learned! Replaced with proper size banjo fitting and re-installed. Successful testing with both fuel pumps circulating fuel back to both tanks. What a relief!!!
Now finishing easy tasks that don't need wings, before moving everything to the hangar for full assembly.