This is just my best guess on the possible problem. But when the Mk 20 problem surfaced, my thought was that the earlier Mk 10 and Mk 15 would potentially be subject to the same potential problem given the similarity in the design of that part. Of course I then wondered why the Mk 20 was having problems with cracks when the much older and much more prolific Mk 10 was not.
On the plus side, finding a crack in the first stage body at an annual service is not the same as having a catostrophic failure. I find all kinds of things wrong with my airplane during the annual inspection and that is the point - to find things that are in the process of going wrong before they reach the point of failing.
I also still would not call it a design flaw, unless you consider it a failure by the designers to anticipate incompetence by technicians. If anything it is a failure of recent Scubapro training programs to ensure their techs are properly trained and knowledgeable.
The irony here is that people will get upset at SP for having techs who are torque wrench challenged but many of these same people will also bash Scubapro for controlling parts sales to limit DIY servicing - a situation where Scubapro would have even less control over inspection and service quality and the long term effects of improper servicing.
I would be very interested in knowing the owner/servicing history of this particular regulator to see what if anything may have contributed to the problem.
In any event, the universal retainer nuts would I think resolve any potential problem. But the questions that need to be answered are:
1. What caused the body to crack on one Mk 10 (out of a huge number of Mk 10's made, all of which have been in service for between 15 and 25 years)?
2. How extensive is the problem?
3. Does it pose a risk of catastropic failure. Ie: will cracks propogate slow enough that they will be caught at the next annual service before they cause a large amount of gas loss or catastrophically fail? If so, there is no risk of a catastropic failure and no need to do a repeat of the NOAA inspired "chicken little" act.
What worries me here is that Scubapro is one of two companies in the industry that provides parts and technical support for their regulators virtually forever. If you own a 35 year old Mk 5 Adjustable or a 25 year old Mk 10 Balanced Adjustable, it can be serviced by a Scubapro dealer as all the soft parts and the majority of hard parts are still available. Most companies will never encounter this kind of problem or, ironically, this kind of critisim because most do not support their regs more than about 10 years anyway. It costs SP a great deal of money to provide this long term support and doing so also poses a potential liability issue. This, along with the reduced repeat business that comes from selling incredibly long lived regulators, becomes an incentive for SP to follow the rest of the crowd and discontinue support a few years after regs go out of production.
In this case, if it looks like cracking may become an extensive problem on the Mk 10, it may make more sense for SP to just discontinue parts support for the Mk 10 to ensure they all end up unserviceable in the year or two. And I suspect this would be economically acceptable to SP as the majority of Mk 10's floating around are probably not owned by the original owner or have a service gap and are out of warranty anyway and SP would not have to replace many Mk 10's with new regs if they did this.
So let's all be careful not to over react to this or blow it out of proportion as the consequenses for SP customers of what ever model could be dire in the long term. The fact is one extensively used reg cracked for undetermined reasons in a manner that did not pose a risk of anyone dying.
