N833DF will not fly this morning. I’m still leaving in an hour or so to do a pre-flight and organize my airplane to bring it home.
The really very good news is the the engines are clean inside and started immediately. On the first blip. All the fuel pumps, vacuums, and apparently the radios fired up just fine as well. So the airplane is ready in all respects, except for a nagging vibration on the right engine.
The previous flights surprisingly are available in detail in my memory while I can’t remember people I met two day ago. I specifically recall trouble shooting an issue with my GoPro camera in the summer of 2016. It had been hanging from the ceiling and taking nice shots of instrument approaches where you could see the panel and the pilots. I really liked capturing those, and was disappointed that I had to stop using the mount.
As the summer went on, I noticed that the videos I was capturing became more unusable due to vibration. The camera was experiencing vibration, and I couldn’t quite figure out why. I stopped using that camera mount before putting the airplane in for an annual inspection in October 2016.
One of the first things I noticed doing the annual was that the right propeller had some play in it, while the left was rock solid. I asked Matt about it, and he gave me a thumbs down. Darn! That prop had just had an overhaul on the previous annual inspection in 2015, so that wasn’t good. The prop shop recognized that as well. Before I said anything, they offered me a steep discount on the second tune-up. The prop came back and was re-installed in 2016.
Missing Solid Clues: I got to thinking that clearly the fact that the prop assembly had too much slop and had been causing the vibration and my camera issue. I was flying along fat dumb and happy and not thinking something might be mechanically wrong with the right power plant. I missed a solid clue!
Now 26 months later we start the engines for the first time and find the vibration still there. That’s not good again. The vibration wasn’t the prop after all, but had to be the engine itself. Matt knew one cylinder showed low compression on the right side, but we’ve seen this before and expected it to right itself after a run. He looked inside and saw that the exhaust valve was loose in the guide, and would need some attention.
He saw other indications on the rocker arm that led him to confer with Rob on the field. Rob reminded Matt of a procedure that reseats the valve without disassembly, and Matt went back to try that. No change in the roughness, so that is a show stopper for today’s flight. Service was required.
Further inspection showed that the exhaust valve was a real issue, so we are pulling the cylinder and having it serviced today instead of flying. I told Matt to repair it last night, but I am going to buzz him shortly and see if I can find out the cost difference and implications of just getting a new one. If the cost is close and I can get this done in days rather than weeks, I’m tempted.
I missed the clues. I’m thinking about one of my friends who suffered an engine failure on takeoff and had to land on a golf course from 700′. Here I was noticing vibration and not driving hard enough to find out why. It is quite possible that the exhaust valve would have ultimately failed completely, and I’d have had single engine operations on my hands. Possibly on the test flight I’d planned for today. None of that scares me – I was prepared mentally and in my flying. It frustrates me that I missed clues that would preclude that drama. The only thing that saved me was how I conduct myself regarding maintenance. I do what must be done to stay safe.
Finances: I paid Barrett Metal, the folks who build my new gear box parts and helped Matt put them in. That one hurt allot, and I’ll be paying Matt up to date today as well. Contract flying and the FlightSafety career make it possible to keep going, and you only live once. Airplanes aren’t cheap.
Here is hoping the cylinder work is the last issue we’ll see, allowing me to burn off another 500 hours on these engines. Those 500 hours will bring amazing stories.