My 2 cents. I’ve had a few cases blister doing nothing. Had another Cato even when epoxied. Jim Jarvis thought it might have the epoxy I used. It was 5 minute epoxy by JB weld. Really can’t say for sure but regardless I epoxy any 54mm 4 grain or bigger.
I suspect that a good epoxy might be better than 5 minute epoxy. I believe that 5 minute epoxy softens with heat. But, I'm just totally speculating. I just try to buy a short amount of extra time, and in the five years that I have been gluing in the closure, I have not had this problem.
Four years ago, when I was lobbying Tripoli to do something about this problem and the Vmax problem, there were some communications with CTI about the issue. What CTI said at the time is copied below. From this, you might hope that the problem was solved. I haven't seen this problem as much in the last couple of years, maybe because some/many/most? fliers know about the problem. Locally, most people are aware of it, and our motor vendor usually tries to pass the word, but I still see this happen from time to time with new fliers and students.
I wish I had documented what the motors were that had this failure. It wouldn't have been that hard, but my belief at the time, when I tried to follow up on this in perhaps a dozen cases, is that there were multiple different types of propellant involved. In my own cases, it was a shorter smokey sam and a longer blue motor. I also had the impression that the closures with the O-rings were an issue (per the pics, including Tim's event). It doesn't appear to me that the motor design has changed, so in the spirit of cheap insurance, I glue in the closure. I also use the Aerotech forward disk on CTI 75's.
Jim
(from Jeroen)
We have attributed all (most) Pro54 mm motor problems to the ID of the liner. For a certain period the ID of the tubing varied widely. We worked pretty diligently with our supplier to fix this problem, and as far as I know this solved the problem. The forward closures should be a tight fit on the liner.
Would it be possible to provide the lot dates and motor types
(P54-xxG-xx) of the failed motors? There should be two date codes on the paper tubes. Recent reloads should not show this failure mode anymore.
Overall, I can say that we see very few problems with the Pro54 motors and the most of them are a bulged case, which we replace.
I recall seeing some posts about epoxying the forward closure on these motors, but can't seem to find them. I may try flying my first Pro 54 tomorrow and did notice there doesn't appear to be a great seal between the closure and the liner. I recall that people mentioned placing a bead of 5 min. epoxy on the closure and letting it set up before use.
