Pro38 BULLETIN Forward Closure Failures

Earlier in this summer Cesaroni Technology Inc issued a bulletin as to possible Pro38 failures. Sunward Hobbies did not pass on this information as no orders for Pro38 were made during the affected time period.

There has been one claim from our clients so we are now issuing the information. Should any clients of Sunward Hobbies have any concerns, please contact us:

From Cesaroni Technology Inc:
It has been brought to the attention of Cesaroni Technology Inc this past week that there has been a high failure rate on several types of Pro38 motors due to forward closure failures. Upon investigation, the root cause has been identified as a failure from de-bonding between the adhesive/epoxy and the forward closure wall. This adhesive is used to hold the delay grain within forward closure housing, and when a poor bond occurs under pressure this can lead to hot gases tracking through forward closure interface resulting in the failures shown.

With further investigation into the recent cause, our manufacturing records showed that our resin supplier of the material used while injection molding the forward closure housing had accidently sent one (1) of four (4) box of material which was slightly different. This mislabeled box contained the same material but had an added lubricant/surfactant, which is compounded directly into the resin to promote/enhance flow during the injection molding process. The introduction of this resin lubricant has caused a bonding compatibility issue with the adhesive/epoxy CTI uses during potting of the delay grain within the forward closure assembly. CTI has already discussed this matter with our resin supplier to ensure this does not happen again.

Unfortunately the forward closure housing itself does not have a unique serial date to identify the effected motors. In a side by side comparison between bad & good forward closures it is extremely difficult to visually identify the difference. With a very keen eye, under the proper lighting & reflection conditions there is a tiny difference that can be seen. The surface of the bad forward closures will appear to be slightly “wavy” [as shown in the image below.]

Additionally, in a side-by-side comparison the bad forward closures will feel more “slippery” to the touch than the good forward closures. However without a side-by-side comparison this will almost be unnoticeable. Again both of these indicators/checks of bad forward closures involve VERY subtitle difference which will be difficult for people to notice without careful observation.

The forward closure housing itself is a common component amongst all Pro38 reloads and will not be specific to any particular reload, propellant type, or date. Therefore there is no easily traceable way to identify the potentially effected forward closure except for establishing the time frame in which the Pro38 reloads were purchased (i.e. assembled) for our dealers. Our records for injection molding production show that the four (4) boxes of resin material in question were used between Oct 22, 2015 to Jan 12,2016.

Again not all of these ProX reloads will necessarily have faulty/bad forward closures. However CTI understands the work & effort the HPR community places into their model rockets and how devastating it can be if a failure occurs. As such to rectify this issue CTI will supply all of the listed dealers with replacement forward closures. Any HPR customer who believes they may have a “potentially” affected forward closure can contact their ProX dealer where they purchased the reload. The dealer will provide at no cost the replacement forward closure. Please identify to your dealer in advance the exact reload model number to receive the appropriate forward closure/delay module. Please dispose of the faulty forward closure/delay module as outline in the instructions and SDS.

We sincerely apologize for any inconvenience or hobby rockets that have been effect by these forward closure. For any hobby rocket failures in flight that occurred as a result of this forward closure issue please follow the regular warranty process by contacting your ProX dealer. The dealers will then provide all the details to CTI so we can ensure you receive the appropriate warranty.

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