CTI 38mm CATO Report

Yeah, I would think that they would push the replacement closures out to their vendors for distribution based on the fact that THEY identified, based on PO, who got what and when.

tbonerocketeer said:

It will be a while for me to get any, as I have no reason to order until propellant is being produced. Freight is too expensive.

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Are you saying CTI will charge you shipping for replacement warranty items??? If so, seems a little strange...oint:

Frederocket said:

Are you saying CTI will charge you shipping for replacement warranty items??? If so, seems a little strange...oint:

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We get replacement/warranty items put on our next order, so we pay the freight. Remember, none of Cti dealer orders ship in a box Fedex ground, they all go on a pallet and ship freight...and I've had some $800+ freight bills for orders before.

With the infrequency of orders in this hobby, you would think they'd realize they need to foot the bill on this and get the parts out.

DavidMcCann said:

With the infrequency of orders in this hobby, you would think they'd realize they need to foot the bill on this and get the parts out.

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This...:confused2: It's not rocket science...

I went through my inventory and found 4 suspect motors and started thinking. (Rarely a good thing.)

If you are using altimeters to deploy the separation charge anyway, why couldn't you fill the remaining space over the delay grain with J-B Weld. You wouldn't have tracking smoke but also no risk of a forward closure failure. Any reason this wouldn't work?

FastAsleep said:

I went through my inventory and found 4 suspect motors and started thinking. (Rarely a good thing.)

If you are using altimeters to deploy the separation charge anyway, why couldn't you fill the remaining space over the delay grain with J-B Weld. You wouldn't have tracking smoke but also no risk of a forward closure failure. Any reason this wouldn't work?

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I've been thinking about that as well. It may work, but on the other hand the epoxy might not stick to it like it usually would since thats what's wrong with the parts. Then again, the only way to figure it out is to try. Perhaps you could static test one motor with the epoxy filled forward closure to see it it's safe?

Maxwelljets said:

I've been thinking about that as well. It may work, but on the other hand the epoxy might not stick to it like it usually would since thats what's wrong with the parts. Then again, the only way to figure it out is to try. Perhaps you could static test one motor with the epoxy filled forward closure to see it it's safe?

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I was going on the assumption that the heat of the burning delay grain caused the sub-standard bond to fail and not the g-forces of the launch. A couple of 2-56 or 4-40 sized holes could be drilled in the aft end of the well for the J-B Weld to find purchase.

Since this issue is probably going to take months to be resolved, this approach is worth investigating. With the H123SK that failed for me at LDRS the failure occurred at the end of the burn (not instantly on the pad). I suspect that it would not take much to make them usable with electronics. The replacement reload I received at LDRS has the same date code as the one that failed. Upon examination, I do not see the pattern described in the advisory (but it is a very subtle difference). I have removed the BP charge and filled the well with epoxy and will test it at our next launch now that our monsoon season has started and we can fly sparkies again. It would be worth while to see what approaches work with reloads with a known bad front closure. With a least another month (or more) before production can start back up at CTI and the logistics of getting the closures distributed this is going to become a bigger issue before long.

Folks, read the CTI, the TRA and NAR announcements on this issue.

The problem is due to the use of an injection molded plastic powder that comes with silicone mold release in the compounded mixture. One of the 4 recently received lots of plastic powder contained the wrong stuff and that box is responsible for the problem.

You need to read the CTI notice and check the manufacturing date. If you purchased a motor with the problematic lot dates, remove the delay assembly and closely inspect it. If the plastic has shiny and/or slippery surface and/or has waves in the circular cylinder above or below the o-ring, you have a defective delay assemble, do not use it. More likely than not, the adhesive that holds the delay grain inside the plastic closure did not bond sufficiently due to the silicon mold release in the plastic, and the grain will burn on the outside in addition to the bottom and ignite the BP ejection charge prematurely.

CTI provides warrantee service via their distributors. If a CTI distributor goes to you launch, bring the motor to them and they may exchange the delay with a known good delay, or if none is available should take down your name and address and send you a replacement at no cost when they receive it. If you purchased the motor mail order, contact the distributor. Or do both as most distributors should take care of you as CTI is paying for the exchange.

FastAsleep said:

I went through my inventory and found 4 suspect motors and started thinking. (Rarely a good thing.)

If you are using altimeters to deploy the separation charge anyway, why couldn't you fill the remaining space over the delay grain with J-B Weld. You wouldn't have tracking smoke but also no risk of a forward closure failure. Any reason this wouldn't work?

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Because the delay assembly plastic contains a silicone mold release and the epoxy will most likely not stick well to the plastic, and the delay grain will let hot chamber gas into the epoxy filled BP well, push it out and allow hot gases into the forward compartment of your rocket and cook it......

Do you have another CTI notice as the one posted in this thread?
The manufacturing data has nothing to do with the production of the delay element.
CTI only gives dates of delivery to the vendors, not specific manufacturing dates of the grains.

bobkrech said:

Because the delay assembly plastic contains a silicone mold release and the epoxy will most likely not stick well to the plastic, and the delay grain will let hot chamber gas into the epoxy filled BP well, push it out and allow hot gases into the forward compartment of your rocket and cook it......

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What I was hoping to do was to make an epoxy plug over the aft end of the delay grain so that it would not burn and be held in place.

bobkrech said:

Because the delay assembly plastic contains a silicone mold release and the epoxy will most likely not stick well to the plastic, and the delay grain will let hot chamber gas into the epoxy filled BP well, push it out and allow hot gases into the forward compartment of your rocket and cook it......

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That's why I use a penny at the bottom of the well.

Jim

bobkrech said:

Because the delay assembly plastic contains a silicone mold release and the epoxy will most likely not stick well to the plastic, and the delay grain will let hot chamber gas into the epoxy filled BP well, push it out and allow hot gases into the forward compartment of your rocket and cook it......

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JimJarvis50 said:

That's why I use a penny at the bottom of the well.

Jim

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I believe Bob was pointing out that if the epoxy in the delay grain side didn't stick to the plastic, then epoxy on the charge well side won't stick to the plastic either. One method of plugging the charge well is to uses Jim J's penny in the bottom of the powder charge well, then seriously rough up the inside of the well to get a mechanical "lock", of course, instead a screw could be threaded into the charge well and epoxy put over that as well (just the little hole between the charge and delay is all that would need a screw). Personally I like the ideas of abandoning the ejection charge, but with the plastic being questionable to bond to I would wait for a replacement closure since my rockets are more valuable to me than having to fly a questionable motor.

Run a tap, drop the penny, epoxy in a threaded cap?

dhbarr said:

Run a tap, drop the penny, epoxy in a threaded cap?

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I like it!