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Building Integrity
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Date:  11-1-2019
Number of Hours:  2.00
Manual Reference:  Section 2
Brief Description:  First and second flight test results

Today had plenty of nerves to work through as no one has installed a set of forged pistons in a UL engine yet. But what a success!
The goal today was to perform 2 short 3 minute ground runs. One at low rpm to check for leaks, and another at high rpm to check for any piston issues. The first run, the engine fired easily and ran quite smoothly. The second run was up to 1700rpm for 3 minutes to let the engine temps all come up and ensure the pistons were not going to seize. No issues. Time to fly
The 3rd run was out to the runway for a 30 min. flight as long as nothing went wrong. The engine spooled up nicely, and takeoff performance was amazing. I still heard piston slap on rollout and climbout, but I knew that when the temps came up the pistons would expand more than the hypers that UL uses. This in fact, was the entire issue behind the piston slap. After climbing up to 4300ft, I circled the airport at different RPM's ranging from 2500--2800, again to slowly open the envelope while monitoring engine temps. This flight was amazing. In cruise the piston slap completely went away as the engine was warmed up.
The 4th and final flight was to be another 30 minutes after checking the engine for any leaks or issues. This flight also allowed me to slowly increase the power up to full throttle, again with no sign of piston slap. The only time the slap is apparent is when the engine temps are cooler than in cruise. After landing I found that the tappets were again in need of adjustment as I assumed they would be, so I got to set them correctly for the next phase of flight testing. She also got a fresh sump full of oil, as the first 1 hour is when most of the metal is made during breakin. I also performed a compression check and all cylinders were in the high 70's. Great for 1 hour of runtime. :)
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tappet adjustment after first flight hour

tappet adjustment after first flight hour

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