Blown Main Fuse
Posted: Fri Dec 03, 2021 12:41 pm
About 6 weeks ago, as I tried to start the Rotax 912ULS in my Tecnam P2004 Bravo, the prop made maybe a half-rotation (maybe more, I wasn't counting at the time) and stopped. All power was gone. The main power fuse (80 amp) had blown. I thought that maybe I had "double-clutched" the starter, causing an extra load on the starter. The fuse was replaced, and I have made several engine starts since. 2 days ago, same thing happened-1 or 2 blade turns and everything died. Blown fuse again.
Again, the fuse was replaced, and the engine started without a hiccup. I did a start-up yesterday with no problem.The engine has 450 hours on it.
I have a (feeble) working theory that the prop position at the time of start-up may be a factor, causing a bigger load on the starter in getting the mass moving when at a certain position. But why now, after 4 years of no issues? Possibly the gearbox is requiring more torque? I'm not an engine guy, so I do not have any real clue.
One instance, I would write off as statistical happenstance. But twice may be the start of a trend.
Thanks in advance for any insights on this.
Again, the fuse was replaced, and the engine started without a hiccup. I did a start-up yesterday with no problem.The engine has 450 hours on it.
I have a (feeble) working theory that the prop position at the time of start-up may be a factor, causing a bigger load on the starter in getting the mass moving when at a certain position. But why now, after 4 years of no issues? Possibly the gearbox is requiring more torque? I'm not an engine guy, so I do not have any real clue.
One instance, I would write off as statistical happenstance. But twice may be the start of a trend.
Thanks in advance for any insights on this.