BVM 91 fan explodes
 

I have a BVM Viper which i have been flying for about 10 years so i have lots of experience with this airplane. So far i have had 3 fan rotors explode. The most recent one about a week ago. What's going on???? Bob Violett says rotor disintigration is very rare. Well not for me its not.
A friend of mine is a metallurgist and fatigue expert. He examined the latest one and here's his take on it. One blade was completely missing and the other six were broken off at their bases, the bases still being retained by the hub.. He says that the missing blade failed in tension at the boss where it is retained inside the rotor hub. The other six were sheared off when they contacted the shroud. The out of balance condition was severe enough that the engine mount broke in two at the forward mounting screw holes. also during this failure the engine over-sped and wiped out the connecting rod and put a hole in the case.

Any thoughts on this??????

RE: BVM 91 fan explodes
 

Sounds like you need a turbine.

:D

Have you thought of putting the Viofan in the Viper replacing the Viojett?

I've never hears of a rotor completely exploding like your's. You boiling them or anything like guy's used to do?

RE: BVM 91 fan explodes
 

I had a rotor explode on a dynamax years ago. Tom said it was totaly my fault. Somehow the rumor got out from one of his buddies that i stuck the starter probe in it " it was sitting on the table" and then it was said that it sucked up the glow starter in the inlet " again sitting on the table". I just gave up and got another one. Russ

RE: BVM 91 fan explodes
 

Well,

It happens. I had a Viojett impellor do something inside the airplane such that when I landed, the rotor had no blades on it. If it happens more than once (not to mention twice) in the same airframe, it makes me wonder if something inside there has changed. I wonder if when you tighten (or loosen up by use) the fan shroud to its mountings, is the shroud somehow being twisted or something? Just a thought. Good luck.

And, yeah, as BVMJethead said, maybe you need a turbine......ASSUMING, OF COURSE, THAT YOU DON'T ALREADY HAVE SEVERAL and were just looking for thoughts on the problem with the DF that you also happen to own...:D

RE: BVM 91 fan explodes
 

Seems very rare.... I worked at BVM, and flew Viojetts' for 10 years, and never had a failure... I only heard of a couple. Perhaps the plastic is changing with age? Do you know when the fan was MFG... There is ussually engraving on the aluminum hub. What engine are you running? How many flights on the fan?
David

RE: BVM 91 fan explodes
 

Well it just so happens that i have a BVM F 100 with an AMT 2800SP but i've only got 13 flights on it. I have a special fondness for my viper which has 100's of flights on it. As a matter of fact i just changed to the third set of main gear tires today.