The idea of testing something I've put together gives me a bit of anxiety. I've read countless posts and write ups on the various testing and even began to write out my own test plan based on other people's write ups. In my searches I came across the recently released EAA Flight Test Manual. I assumed this took far more man hours to create by experts knowing what they're doing and for $18 you can't go wrong. Not writing a review on the product but can tell you it helped me wrap my head around some things from what I would consider a definitive source. They're also very clear that your testing actually should build upon this base for your specific project. For example Yaw Damper testing isn't covered. So if you have that it should be worked in once you know the plane can fly and land safely.
The first two tests they recommend doing is the Fuel and First Engine Start. I'm going to apologize I don't have pictures detailing much of this process. During both evolution's I was too focused on the event themselves rather than taking pictures.
Fuel Test
I was well prepared for this. I picked up two 5 gallon Jerry cans, weighted each, put 2 gallons of each and then weighted that. My idea was I would run those two gallons out time it and then extrapolate the results. That would also give me the weight of any fuel left in the tanks. That was the idea at least.I set the nose at about 5% nose high. I've seen pictures of people putting their plane in all sorts of pitches to ensure it runs. That's probably important for acrobatic tests, I'm going to guess it's not needed on a cross-country machine as it also wasn't suggested in the EAA Test Cards.
With the plane set up and the fuel line disconnected from the mechanical pump I was ready to get to test. With the bucket and timer set I hit the boost pump. It kicked on right away and... well nothing. No gas, didn't seem like any air was running out.. a big flat zero flow.
No gas, is no good so I got to troubleshooting. Did everything from switching tanks, to checking lines to adding more fuel (throwing off my scientific weight tests). I ran low pressure air up through the system and confirmed not only was the fuel selector correctly plumbed but there was no type of blockage. I fiddled with things more having no luck.
I made the assumption that given the low wing nature and that the pump hadn't been run with fuel that it was as they call it 'airlocked'. I ended up using a shop vac to suck some fuel out from the front. Put the pump on and walla! Fuel! ummm lots of it.
Because I was turn on and turn off the boost pump at this point I had given up on timing anything. I also spilled a bit of fuel at the wing root, under the seats, ect... so my weights would have been off anyhow. I let the pump run on the right tank for a bit, along with the fuel there was an oily mess that I assume was from the pickling of the boost pump.. may or may not have been an issue on the initial priming.
For the other tank I did the timing and ran it for exactly 1 min. Weighted the contents minus the bucket and came up with close to 7 pounds. Extrapolate that out and it's roughly 60 GPH. Per the EAA guide they recommend 150% of your max anticipated fuel flow. The lycoming manual provided some ranges and the max I saw was 28 GPH so I needed to be at least 42 GPH which I was above so I called it good.
Should also not that I had no leaks until I connected it all back up and ran it through to the servo. I apparently forgot to double check the servo connection so it pissed some fuel out past the nose gear. Once that was tightened again no leaks and was getting ample fuel pressure.
Now I have to revisit the usable fuel test. At this point I'll run both tanks dry and measure what's left via volume instead of weight. I don't anticipate much given others experience with the RV-10.
First Engine Start
After another few weeks of hangar sessions it was time to test the engine for the first time. Hey at least I know it has fuel! Everything else, not so sure on. I reached out to my local A&P to get assistance from him and his shop. I also had some questions I wanted to bounce off of him and as always he was extremely accommodating. If you ever need a shop in the Oklahoma City area I highly suggest Brian Butler and his guys at Reliable Aircraft Maintenance out at KHSD (Sundance). These guys are the best hands down!
Okay back on track, Brian and his crew looked over the engine and got it ready for the first start. Unfortunately the starter wouldn't actually spin the bendix. It would extend as it should but then just "click-click-click."
Worked with Brian, walking through things I wired up and how certain parts were connected. It ended up being the ground I hooked directly up to the Starter on apparently the wrong place. So if someone tells you to hang a ground off a Sky-Tec starter where there's a boot covering the black wire... they're wrong. You could probably hook it directly up to one of the other holes on the starter but I decided to just bolt this ground directly to a close by engine bolt, away from any arcing danger. So now I have dual engine grounds!
We finally got the prop to start spinning. They ran it through with the bottom plugs to build up oil pressure and that's when the next issue occurred. My oil cooler actually had a small really hard to see pin hole in it. Called Bill from Airflow Systems and he's sending me a replacement, even offered to do next day. I declined next day as it's about to get sub 40 which means I'm not working on plane stuff unless it's either inside the plane or homework activities. The leak isn't big and no clue how it happened but in the end Bill stands by all his products and is always great to talk with. We just threw a connector on the two oil hoses so we could continue with the engine start, minus the oil cooler.
We did a series of three starts actually. The first start seemed a bit high on the RPMs so he shut it down in about 5 seconds. Made some throttle adjustments and ran it again, this time I couldn't find the RPM so we instead tested the alternators and looked at what was showing up on the EFIS. This run was about 30 seconds. I went into the G3X configuration and changed up the RPM settings and alternator screens for the last run.
The last and longest run was about 3 mins which was the max I wanted to go. Even though this engine spent time on a test cell I still plan on using ground runs very sparingly. Engine started great, EFIS engine readings were solid minus RPM (Now know I put the sensor on the wrong part of the mag), Alternator Shunts (Emailed the Garmin folks to validate how it should be set up to see amps, volts were showing correctly but 0 amps). The most important part was the engine ran, nothing blew up and it was down right amazing to see it all! Here's a picture of technically the first spin, with the plugs out to build up oil pressure.
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