Hey everyone,
I had an interesting flight on this past Saturday, here in Montreal Quebec, and although the aircraft is in maintenance as we speak, I thought it would be a good idea to get some feedback from you owners. My plane is 1979 Mooney M20K 231 with the 262 Trophy conversion.
Saturday: My mechanic changed the Right magneto for a brand new one on Friday. The RPM 's on the ground were really good and stable. Run up was nice, with a 75rpm drop with the mags from both (from 1700rpm). On the initial climb (Turbo TSIO-360-MB4 - 36'' / 2700rpm), everything felt good. I leveled off at 2000ft and pulled the power back (29"/2600rpm). Then, I was cleared for 5500ft, proceeded to applying full power gently and climbing with roughly (35" / 2670rpm) in a Vy speed (96kts) climb. Everything looked great until 4000ft when I had a major drop in RPM, rough engine running, loss of airspeed and cylinder 5 was indicating a temp drop in both CHT / EGT at the same time. Cyl 5 showed a dead EGT and never came back, but the CHT dropped and back to normal when coming back to the approach. Bare in mind, I was still within 5nm of airstrip, with Terminal. Once pulling the power below 18", everything felt normal. There also was not any change in engine sound, the engine sounded like it was still running on 6. On the ground, I was able to land and taxi back, no issues as engine ran smooth., I even did run up with mag check after flight, both were spot on. I am uncertain what has happed, but had to rush back to the field and park the aircraft. The initial thoughts when everything failed, was "Did I lose a mag?", that feeling.
Sunday: I sent all details from the JPI EDM 700 to Savvy Aviation and they came back with some ideas pointing towards induction leaks.
Monday: Good thing about having a hangar at a maintenance facility !! Team of experts were on it, this is what we did.
1) Checked all fuel nozzles, removed and inspected. Did a pump out test to see equal spray amount. Everything good.
2) Ignition tests, checked spark plugs and cables, Everything good.
3) Ran a borescope into cylinder 5, everything looked good.
4) Removed the valve cover, a checked rocker position, removed rocker and inspected valves. We thought maybe a valve a stuck, negative in the findings. Everything good.
5) Induction test, we checked all possible induction leaks, found no issues.
6) Wastegate / turbo function. We ran the borescope into the wastegate, manually checked the function, all good. Ran the borescope into turbo, all looked fine.
Our last option yesterday was to remove the mags and inspect them, that is where we are at. The last uploaded file was not a flight, it was a run up mid day with my tech to see if we can replicate the issue. Everything ran very smooth...
Green line (EGT5) taking a flat dive and never coming back until engine off. During a runup test on Monday, EGT5 was back online, like normal.
Let me know what you all think!
Thanks.