I’ve really hesitated sending this note afraid my lack of knowledge may be demonstrated. But what the hey … here ‘tis.

 

Among other things, JPI continues to espouse a wife’s tale on “shock cooling”. I’ve asked many times for them to provide empirical data to support their claim. Apparently no empirical data exists and that translates to rumor or worse. I was going to buy their product but changed my mind when I learned they sell products by scaring people about events that don’t happen. From their website:

 

“An old and common misconception that other manufacturers of EGT monitors promote is that it is not necessary to know the exact exhaust gas temperatures of your aircraft's engine. However, if you have read recent reports, shock cooling can be catastrophic! The EDM alerts the pilot of those conditions which are most vital to the maintenance of well performing engine. The value in measuring EGT lies in finding the ideal ratio of fuel to air that results in complete combustion, and in long-term trend monitoring.”

 

What reports? What data? Catastrophic? How is shock cooling associated to EGT? Wouldn’t that be CHT? I understand … not necessarily.

Their claim is cooling by sudden reduction in throttle will/could cause a catastrophic event. What is the event? Cracked head, cylinder? Driving the engine? Sticking valves? Wouldn’t flying into rain or worse be an event you could expect sudden cooling to cause major damage? Or how about turning off the ignition? From making plenty heat to making none. Quick cool down (>100ºF/minute) would be equal to shock cooling. This wife’s tale continues to be over my head. If I’m not mistaken, GAMI says shock cooling is a myth. Wouldn’t they know? Pointing to a manufacturer’s prohibited operating regime (pull the throttle to idle at altitude), legitimate or not, is no justification to make instruments that prevent you from operating there. Do the tests before you sell instruments that prevent you from doing something that doesn’t matter. Well, the idea of “if it’s good enough for Lycoming and Continental, it’s good enough for me” just doesn’t sell today. CYA is a big business justification.

 

So this is perpetuating manufactures’ CYA on operating under any circumstance that might – MIGHT – cause a warranty issue. LOP for example!

http://www.avweb.com/news/maint/182883-1.html

 

I’m not saying their instruments are not quality. I’m satisfied they are good quality. They likely report accurately. However, measuring something and making unsubstantiated claims as to what the measurements mean is not a responsible way to sell a product.

 

JPI? I think they’re reaching and with no limb to grab (competition is fierce) they may claim things with their instruments that are useless. You want to measure it and do something about the measurement? Fine by me. But gee whiz, airplane stuff is already so expensive … why spend it on things that don’t matter? That’s not a rhetorical question. Educate me.

Jim

 

 

technical readers press delete.  I just wanted to say I have been so excited with jpi ever since they decided they owned my data that I used the edm700 that came with my project to monitor temperatures around the cowling and bleep if something gets too hot.