March 2022 –
In January of 2022 I started noticing a vibration in flight that initially I had thought was perhaps the prop being out of balance. It quickly grew more pronounced though, even as I was attempting to balance it. The engine itself seemed be running just fine, it was making good power, but the vibration was not normal. I checked blade tracking on the prop and noticed that there did seem to be a small discrepancy of a couple degrees between blade angle on the 3 blades. I took the end cap off expecting maybe there was an issue in the link arms that connect the blade angle pins to the piston. Instead what I found was that the blade root bearing has destroyed themselves and chunks were flying around inside the hub.
I removed the prop and sent it to Whirlwind for repair. Unfortunately, a month later I would get word that it would require a new hub, and they no longer make the part. So after 10 years and about 600 hours, I had no prop. To say the least I was disappointed in WhirlWind. I wasted a lot of time and money on that prop, not least of which was after learning they built it to the wrong spec during phase 1 testing.
At this point my only option for a constant speed was MT, and I’d heard enough horror stories of getting service from them that I wasn’t about to spend another $20k for the privilege of getting more bad support. As much I appreciated the climb performance of the constant speed, I had to admit it just wasn’t worth the expense and maintenance trouble. Instead, I placed an order for the tried-and-true Hertzler Silver Bullet and went to work converting the engine for fixed pitch use and removing my prop governor and associated controls.
The switch to a fixed pitch prop was also one of the things explicitly called out in my Op Limits as a change that required notifying the local FSDO for concurrence of an appropriate Test Plan. I called them up and explained what I was doing, and after a brief bit of confusion on their end as to the proper procedure, they had me email them my proposed test plan. They quickly replied that it looked good and that all I would need to do is log completion of the tests along with any changes in performance in my logbook and POH.
Once the prop arrived, I quickly got it mounted and balanced. In my test plan I had estimated it would take 4 flights that would total 5 hours to work through the test cards. It took exactly that. Climb performance took a small hit, but cruise performance seemed about the same or a touch better.
After a week of dreary weather, I had just enough time to take 4TF for BFR flight before Bob and I would be taking it a on cross country to Dallas. Nothing like cutting it close.
