Hypothetical - 2 AI transmitters instead of backup SPG?

[caruso]

You just answered your own question.

In other words, you've done no studies, you have no data, you simply assume that because your dive computer does not have user replaceable batteries, then most do not.

Got it.

 

[blake7]

If you have two 18 wheelers get transmissions rebuilt at the same time and then subsequently exhibit similar driving profiles the two transmissions will likely not both fail at the same time or near the same time, in fact the probability of that occurring is rather remote.

Are you sure about this? Isn't the ETOPS Limitation on Dual Maintenance rule to never overhaul/check/maintain both engines at the same time at the same location? To prevent the exact problem you are describing?

 

[loosenit2]

Are you sure about this? Isn't the ETOPS Limitation on Dual Maintenance rule to never overhaul/check/maintain both engines at the same time at the same location? To prevent the exact problem you are describing?

ETOPS (Extended Operations (ETOPS) of Multi-engine Airplanes, applied to air carrier (part 121), commuter, and on-demand (part 135) turbine powered multi-engine airplanes used in passenger-carrying, extended-range operations. rules are specifically for multi-engine long range aircraft.) Those rules do specify that:

Dual maintenance is a concept relating to repetition of maintenance errors on redundant systems. There have been instances of a single mechanic repeating a maintenance error on multiple systems. An example of dual maintenance error is failing to install o-rings on engine oil or fuel components on multiple engines. Establishing procedures to avoid dual maintenance can minimize the probability of such errors. The use of two or more mechanics reduces the risk of this type of error. Routine tasks on multiple similar elements, such as oil and fuel filter changes, should never be scheduled and assigned on the same maintenance visit.

However, the FAA is aware that under some limited circumstances, dual maintenance may be unavoidable. For instance, a pilot's report of a discrepancy on an ETOPS significant system may require maintenance on one engine at the same time as a scheduled maintenance event for the other engine. In such cases, the certificate holder must establish and follow procedures to mitigate the risk of a common cause human error.”

These rules are in place for specific types of aircraft used in specific ways. The FAA does not require these rules for all maintenance and I have never seen a similar rule used outside of aviation; although it is possible some other communities use similar rules.

You appear to be applying an extreme example as justification for applying the same rule to routine maintenance in all circumstances, a leap even the FAA does not make. There is a significant difference between a jetliner carrying several hundred passengers and using two scuba transmitters on the same first stage.

If you want to apply extreme case maintenance procedures to everyday maintenance no one will stop you; and I won't criticize you for doing so, but the probabilities and impact just don't support the necessity.

I really want to be your mechanic though, because I will get to charge you 10 times the amount it costs everyone else to do routine maintenance. BTW you don't self service do you because the extreme application of the rule/argument you posited would preclude you doing that due to the increased potential for compounding the same error over and over again.

 

[loosenit2]

My position is not over personal. .

But your attacks are...."I don't think you have any concept of....". You are attacking the person rather than simply disagreeing with their position on the merits...this is a logical fallacy called an ad hominim attack. You did it in a more subtle way than is usual but you did it nonetheless.

 

[NAM001]

In other words, you've done no studies, you have no data, you simply assume that because your dive computer does not have user replaceable batteries, then most do not.

Got it.

I think you are twisting what was said. I would have to say that all computers have user replaceable batteries, Most that I have been nvolved with need special tools to do it , and not a simple nickle or quarter to remove the battery cover. the simplicity of the task is what IE shearwater built into process. compare the shearwater with say an aeris T3 that needs a spanner tool to remove teh back cover of the computer to get to the battery and uses a very frail oring to boot. Aspect like that require a study of any kind. And yes iI have owned them and when the battery goes you are stuck till yo can find a shop or the tool and hope to change it leak free.

 

[scubadada]

I think you are twisting what was said. I would have to say that all computers have user replaceable batteries, Most that I have been nvolved with need special tools to do it , and not a simple nickle or quarter to remove the battery cover. the simplicity of the task is what IE shearwater built into process. compare the shearwater with say an aeris T3 that needs a spanner tool to remove teh back cover of the computer to get to the battery and uses a very frail oring to boot. Aspect like that require a study of any kind. And yes iI have owned them and when the battery goes you are stuck till yo can find a shop or the tool and hope to change it leak free.

I dive an Oceanic VT3, essentially the same computer, 9 years old, 1380 dives, 1451 hours, it's perfect, what's the problem?

 

[NAM001]

But your attacks are...."I don't think you have any concept of....". You are attacking the person rather than simply disagreeing with their position on the merits...this is a logical fallacy called an ad hominim attack. You did it in a more subtle way than is usual but you did it nonetheless.

I can play the same game you are, I did not make an accusation , By saying """""" think"""""" it becomes my opinion. and you also just did the same thing by so called attacking the person and not the merits of the opinion. That does not forward any conversation to being more productive. The merits of more complicated means more prone to failure should be an accepted concept. to replace a complicated process with an equal or more complicated method as a backup should raise questions regarding the soundness of the decision to do so. Also as I said before If you look at the DIR process it is completely 180 in regards to the idea of using a computer as a replacement for another computer when a simpler method less prone to failure exists. Their thought would be use the simplest, time proven lowest failure rate method as the primary process. So please re read my comments with that aspect in mind. These discussions should be able to conducted with out those that do not like your message to nit pick words or spelling or punctuation as if it has bearing to the message.

So again I will say that although I am not a strict DIR company man I agree with their view of the concept of simplicity being the best and to deviate you have the unavoidable chance to take on failure you are not equipped to handle.

 

[NAM001]

I dive an Oceanic VT3, essentially the same computer, 9 years old, 1380 dives, 1451 hours, it's perfect, what's the problem?

I did not say there was a problem wit the VT only that there are computers that are more user friendly to things like battery changing than others. You have to admit that a computer that can take any battery you can fit in it and can do so as easy as changing a household flashlight battery was designed not only to be pretty consumer friendly, but probably made to be done such as a cave man can do it successfully. And still with that being the case i would never get rid of my SPG from my kit because of its simplicity and reliability.

 

[NAM001]

But your attacks are...."I don't think you have any concept of....". You are attacking the person rather than simply disagreeing with their position on the merits...this is a logical fallacy called an ad hominim attack. You did it in a more subtle way than is usual but you did it nonetheless.

my opinion is that their position lacks the very merit you speek of.

 

[loosenit2]

my opinion is that their position lacks the very merit you speek of.

I would just as soon submit myself for an interview with Rickover or volunteer to beat my head against a concrete wall repeatedly as continue this conversation. The intractability and illogic are simply too much for me. I concede the internet to you sir, it is yours for the taking.