I had a prop fail this weekend. On my second flight of the day, I heard weird noises as I applied power to take off. The plane also had almost no power. I immediately cut the power to low idle, limped around the pattern, and thankfully landed the plane safely. At first we all thought I had lost a cylinder on the motor. As I went to remove the spinner, I noticed that the prop had delaminated, and split along the leading edge. I was really lucky it didn't totally fail in flight, as this would have surely done a lot of damage to the plane.
So here's the question. The prop is a Mejzlik 30 X 12 CF, which I bought new only a few weeks ago, because I heard it is a good prop for the windy conditions at the Shootout. It only had about 15 flights on it. The picture below shows the prop on it's second day of flying. A friend took the picture and sent it to me. When I first saw the picture it looked to me like the prop was flexing in a weird way. But thought either it was supposed to do that, or that it was just a weird photographic effect. After the failure, I went back and looked more closely. The plane was clearly at low idle, which is only about 1,300 RPM. This is shown by the fact that it is still attached to safety starting strap which is slack, at high idle (1,800 RPM), the plane would be pulling on the strap. Even at this low RPM, look at the flex in the prop.
What do you guys think? The prop showed no exceptional vibration or noise at this point. Are props supposed to flex like this? Does this show a weakness in the prop from the beginning, that indicated this prop would fail? I'd really like to hear from you prop experts out there.
Click on Picture to View it larger.
