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Author Topic: Cox 5x3 safety tip props  (Read 1269 times)

Offline Frank Sheridan

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Cox 5x3 safety tip props
« on: July 13, 2009, 07:05:12 PM »
Hello all
  A couple of months ago on another forum I read a post about the Cox 5x3 safety tip props being easy to break. There is a youtube video..   I didn't think too much about it because I have never had a 5x3 safety prop in my possession...until now. I bought some new Cox parts and a prop came in the bag. I recognized the prop from the video, so I gently flexed it - and it broke quite easily, in fact I heard it cracking before it broke. Upon further examination I could see surface cracks develop early in the twisting motion. They run from the leading to the trailing edge of the blade and are equally spaced like railroad ties. The weakest point seems to be right at the hub. Has anybody else experienced this? Are the props safe to use? By the way, I have nothng but good things to say about the folks who now own the Cox inventory - I was very pleased with all the other parts.
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Offline ray copeland

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Re: Cox 5x3 safety tip props
« Reply #1 on: July 13, 2009, 07:21:33 PM »
Frank, i bought 5 of those and the first 2 i flexed broke the same way. Boiling the others for 10 minutes helped a lot!! They still showed the flex cracks but I have one on a norvel for around 10 flights now!!
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Ray from Greensboro, North Carolina , six laps inverted so far with my hand held vertically!!! (forgot to mention, none level!) AMA# 902150

Offline Frank Sheridan

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Re: Cox 5x3 safety tip props
« Reply #2 on: July 13, 2009, 07:48:59 PM »
It's strange because the blades only break at the hub. I have some older Cox props and you can almost tie them in a knot. Personally I am not afraid to use the new ones but I don't want anyone else getting hurt.
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Offline John Castle

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Re: Cox 5x3 safety tip props
« Reply #3 on: July 13, 2009, 08:11:47 PM »
I think they actually sell the 6x3 as the flexible prop and sell the 5x3 as a "safety" prop because of the no cut tip. I actually like to use their 6x3 flexi prop cut down to 5' because I crash so much. :)


John
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John Castle
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Offline Larry Renger

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Re: Cox 5x3 safety tip props
« Reply #4 on: July 14, 2009, 08:05:22 AM »
Cox black props should not be breakable by bending, even a sharp right angle bend.  However, there seems to be a bad batch out there, and I don't know how to test, other than bending.

I was shocked to have a brand new black 6x3 throw a blade a few weeks ago.  New prop, stock Golden Bee, no abuse, it just came apart about 5 seconds after the engine started.  Fortunately nobody was hit.

You can boil them for a week, but if the molding is bad, it is a dangerous prop, as the flaws are internal.
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Offline kenneth cook

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Re: Cox 5x3 safety tip props
« Reply #5 on: July 15, 2009, 05:11:24 PM »
       I recently had a few props do just the same. The first prop was an older 5x4 with the rounded tips. I can understand this prop failing for 2 reasons, one its age and the other I was using it beyond its design parameters. I then pulled an additional 5x4 out and when I flexed it, several cracks formed all the way from hub to tip. I thought this was odd. I then recently purchased a few 5x3 safety tip props as described above. I wasn't aware of what these props actually were until seeing them listed on recent advertisers sites. All my 5x3's were square tipped without that little knob on the end. Those props seem indestructible. I have several from 25 yrs ago that are still fine even when flexed. Well I put one of the new ones on and combined with a real windy day the plane struck the ground launching off both blades. I had to laugh as I've never seen this happen ever. I then installed another one. I bought 10 and proceeded to give it another go,  well it wasn't 5 minutes and it happened to one of the blades. I just figured this was just my typical luck so I discarded those props. Its definetly a concern to find out its happening to others. I myself am a big fan of the APC's but the cost is a bit much for the 5x3's. I will add that the best running props I've used to date are the 5x3 and 4.75x4 APC's. Ken
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Bernie Eisele

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Re: Cox 5x3 safety tip props
« Reply #6 on: August 08, 2009, 05:05:27 PM »
The posters are correct, some of the 5x3ST props broke easily. We received about 20,000 of that size from Cox and found a box with about 2,000 that were brittle, unfortunately only after we had mailed out hundreds >:(

We discarded that box of props and the next box is perfectly fine. Anyhone that bought such props from us (that were brittle) will get replacements if they let us know.

Genuinely sorry for any inconvenience that this has caused.

Bernie
Cox International
www.coxengines.ca

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Offline jim gilmore

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Re: Cox 5x3 safety tip props
« Reply #7 on: August 08, 2009, 05:11:40 PM »
Clap,Clap,Clap.....very upstanding customer service I applaude you.
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Offline Frank Sheridan

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Re: Cox 5x3 safety tip props
« Reply #8 on: August 08, 2009, 07:17:40 PM »
This is why I am a return customer.
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Offline Robert McHam

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Re: Cox 5x3 safety tip props
« Reply #9 on: August 08, 2009, 11:02:40 PM »
Bernie, As soon as I am able to financially, I would be glad to do business with you!
Sure wish you had some Tee Dee .051 piston/cylinders.

Robert
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Bernie Eisele

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Re: Cox 5x3 safety tip props
« Reply #10 on: August 09, 2009, 10:46:01 AM »
It's the ONLY way to do business and we treat our customers the way WE would like to be treated when we buy. After all, why should a buyer bear the consequences of defective merchandise? It's the sellers responsibility and not the buyers.

And, Robert, we have a bit of a waiting list for 051 cylinder/pistons but do get the odd one in every now and then and have noted your request.

Cheers
Bernie
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Offline Bob Furr

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Re: Cox 5x3 safety tip props
« Reply #11 on: August 15, 2009, 08:08:39 PM »
Bernie is the best... I have made several purchases and have been very happy with the service.
Bob
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Offline Jeffrey Olijar

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Re: Cox 5x3 safety tip props
« Reply #12 on: August 17, 2009, 10:56:26 PM »
I got my .049 rebuild kits and they were well packaged and I must say the prop was a nice touch.  I didnt see any cracks on my and it is quite flexable.  I guess I got lucky.
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If it ain't broke, fix it till it is.

Bernie Eisele

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Re: Cox 5x3 safety tip props
« Reply #13 on: August 18, 2009, 07:14:48 AM »
Jeffrey,

Glad to hear that everything was OK.

As to the props, it's not a matter of luck anymore as we have weeded out the box of defective ones. The next box of 2,000 seems fine and we do keep an eye on the 5x3 props as we go through them.

Cheers
Bernie
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