Dropped my helmet

FGanger · Post by **FGanger** » Mon Sep 19, 2005 8:49 pm

I think I have the answer for what to do with your helmet. Just pack it up and mail it to me - provided it's "fat head" size. I'll take it off your hands, I'll even pay the shipping.

Of course if it fits you and not me, I'd just wear it and never worry about it. Not even once.

But remember if it is XXXL, well, you know what to do.

Frank

Post by **new2BMW** » Mon Sep 19, 2005 10:28 pm

I am no helmet expert.

I am a mechanical and polymer engineer working in the aviation industry. I oversee the inspection of composite materials virtually every day. There is a simple inspection procedure that can be used to determine whether your helmet's shell is damaged.

This method is the single most common method used to inspect carbon fiber and fiberglass reinforced platsic (FRP) airplane parts. If you aren't comfortable with this inspection method, you might want to take the train next time you go on vacation.

Because composite materials are composed of a hardened plastic resin impregnated into a multi-directional fabric of fiberglass or carbon fiber, composites don't just crack like metal. If the resin cracks, the fabric flexes and the plastic resin delaminates around the cracked area. Because of the delaminated area, a crack in FRP will actually be represenbted by a larger area than a traditional crack in metal. You can inspect this with a very simple method.

Holding a medium sized coin such as a US quarter, UK pound, etc. between your thumb and forefinger, gently tap the entire surface of the helmet. Not a hard tap, but hard enough to make an audible clacking sound. Listen very carefully for the sound to change throughout the surface area. Delaminated composites will make a dull or splintering sound while in-tact composites will make the hard clacking sound. If you hear any sound other than the hard clacking sound, the composite is delamianted and will not provide sufficient impact dispersion.

This method does not work for thermo plastics such as polyethylebne, but is the most common method used for fiber reinforced plastcs such as the material used by Nolan.

Additionally, some helmets are painted with a rubber based paint that will deaden the sound. If this is the case with Nolan, this inspection method may not be the most effectoive. You'll know right away if the entire shell sounds dull when tapped.

If you are still not convinced about the integrity of the hemlet's shell, you can find inspection services in almost any medium or large city that can accomplish ultrasonic inspection. (Look in the yellow pages for laboratories) This will take them about ten minutes and cost you about $40.

darthrider · Post by **darthrider** » Tue Sep 20, 2005 8:51 am

Good stuff Jeff!
What is it they say..."A test is worth 10,000 "expert" opinions!"

Post by **scottybooj** » Tue Sep 20, 2005 10:06 am

Domo arigato jeff-san

Post by **new2BMW** » Tue Sep 20, 2005 5:09 pm

What is it they say..."A test is worth 10,000 "expert" opinions!"

........or 1000 guesses. (Same thing as expert opinions in my experience)

*******************************

Doi tashi masu te Scott san.

FGanger · Post by **FGanger** » Tue Sep 20, 2005 7:03 pm

Jeff,

I was so close to getting a new helmet. Couldn't you have waited a couple of days? Now I'm going to have to keep wearing my old, smelly 10 year old helmet. That's not right man.

Frank

PS: Great info, thank you for the posting.

Post by **new2BMW** » Tue Sep 20, 2005 7:24 pm

Frank, here's a little secret for you. If you do the sonic tap test slightly harder than normal, you will always find a defect. (How do you think miy company stays in business!)

malcolmm · Post by **malcolmm** » Wed Sep 21, 2005 6:31 am

Doesnt' everyone drop their helmets from time to time?

Mine has rolled off the saddle once or twice. I've taken to puting it on the ground when I'm re-fueling. A friend saw me do that a while ago and warned me about ants getting in and giving me an awful surprise. Meh... I figure I'll just check it out before puting it back on.

Incidentally, the other day I re-fueled and placed it on the bowser. I rode off and forgot to put it on. It didn't take me long to realise I was without my bashhat... I turned around and retrieved it from the bowser... a young lad sitting in the back of a SUV smiled at me and gave me a sign as to say... "leave it off, it's more fun"

darthrider · Post by **darthrider** » Wed Sep 21, 2005 1:21 pm

I'm afraid if I put my helmet on my bowser he would bite me.