When Plane Power wrote its installation instructions, it would have been helpful to include an image. The information does however, include the following language:....where on the alt do you want the blast tube....front, back, side...??
Would be interested in hearing if anybody has had to replace the diodes one of these alternators who did not use a blast tube.
I installed a blast tube when I built my airplane. The ND alternator bearing failed at 124 hours. We were on the way to Oshkosh and ended up spending two days in Scottsboro, Alabama with a bunch of very helpful folks. We found an alternator shop in a neighboring town that took three alternators and made the one we have now. The bearing spun in the housing and ruined the rear housing. It also ripped some things loose that needed to be connected!!!!! I don't know how much blast tubes work to preserve bearing life.
anyone have any good shots of who they affixed the blast tube towards the alt? I was trying to work through this today I didn't come up with anything I was satisfied with...
Also, where on the alt do you want the blast tube....front, back, side...??
Ryan, I have a B&C and I was going to mount the air tube where you (and many others) have it. B&C advised me that this was not the correct position. According to B&C (and presumably the PP is the same) their alternator sucks in cooling air through the front and rear and exhausts heated air through the sides (centrifugal fans). In other words you are aiming your cooling air at the place where the hot air is being expelled and that is virtually useless.
I believe the cooling air needs to be directed to the housing at the very rear of the alternator. That will be effective in cooling the alternator, and most importantly the diodes in the rear.
Yes, that is also true for Plane Power alternators. I was told exactly that by Plane Power tech support.
No blast tube on my Plane Power, 450 hrs so far. The alternator that Vans supplied in their kits prior to the Plane Power, lasted 100 hrs with a blast tube.
I attribute that failure to improper operation though. I used to turn the alternator field on after engine start. After much discussion on these boards 5 or 6 years ago, I learned that, that was completely wrong. (Thanks GMC George), I now "gang" the alt field with the Master switch, On together, Off together. A relatively small sample, but, when I ask someone who has had early alternator problems, how they turn the alternator on, every one of them had been turning the alt field on AFTER starting the engine.
While you're working at the alternator....a few well-placed dabs of silicone between case and rear cover will prevent the aluminum cover from vibrating, fracturing, and potentially shorting something.
At the risk of sounding cynical (who me?)..I wouldn't bother with the blast tube cus the rear bearing will fail in 300 hours anyway!
My PP alt was an expensive waste of time.
Frank