Anyone else having trouble with these failing? I've had 3 fail so far. Just trying to figure out if I'm having terrible luck, if I'm terrible at installing them, or if others are having issues at well. One was bad right out of the box and 2 have failed in 30 min or less since install.
Thanks in advance.

Yes, I had one fail. The reason was reported to me that fuel vapor contaminated the transducer. Once this happens, the transducer is done. I recall that there are instructions on how to fabricate a loop in the pressure tubing as well as drilling a vent hole or something like that in the tubing. That may be your problem.

Squash wrote:Yes, I had one fail. The reason was reported to me that fuel vapor contaminated the transducer. Once this happens, the transducer is done. I recall that there are instructions on how to fabricate a loop in the pressure tubing as well as drilling a vent hole or something like that in the tubing. That may be your problem.

Thanks Squash. No mention of a loop in the install instructions, but they do talk about the possibility of a small hole. What did you use to make the small hole? Just a pin hole in the plastic line or?? I still have a hard time believing that a small amount of fuel mist would wreck the transducer in 10 minutes of operation. There's no staining on the plastic which they tell me is indicative of fuel presence. Still waiting to hear back from them if they've found out what went wrong in the first one I sent back.

I had one fail that was defective from the factory. They had switched vendors and a few bad ones made it past QC according to EI. I also had one fail after 2 years but that was due to fuel contamination. You could not see any staining in the tubing, just a hint of fuel was there. Got the replacement and put two loops in the tubing prior to attaching to the transducer. I opted for the loops vs putting a hole in the line. It’s been 4-5 years now with zero issues.
I have installed 4 of these in other planes and no issues going the loop route.

Repetitive failures are exceedingly rare with our manifold pressure transducers. In such cases, we typically find something in the installation as the root cause. Having said that, we are always concerned when we hear reports of repetitive failures and are very interested in bench testing the suspect transducers to see if there is some kind of defect that needs to be addressed.

What we normally find is that crankcase pressure can push a small quantity of fuel through the manifold pressure hose, damaging the transducer. The small hole that was suggested (and included on many factory aircraft) is not a drain hole, rather, it is there to alleviate any pressure behind the fuel. That is why we do not suggest a loop as the pressure would likely push the fuel past the loop eventually.

Additionally, heat and vibration are not kind to any electronic component and care should be taken to isolate components from both.

A1Skinner, thank you for your patience. We will certainly let you know what we find.

darata wrote:That is why we do not suggest a loop as the pressure would likely push the fuel past the loop eventually.

I find this odd since it was you who suggested the loop to me when we spoke on the phone.

Perhaps I should clarify having spent some time in the mind of one of our incredibly bright engineers.

Fuel can work its way up through the manifold pressure transducer hose through capillary action. As such, if the manifold pressure transducer is installed lower than the engine port, using a loop may be beneficial as gravity will slow down capillary action as the fuel attempts to work its way up the hose. Manufacturers were aware of this years ago. To combat it, they put a very small pinhole in the manifold pressure line. In doing so, the higher atmospheric pressure pushes against the capillary action as the air pressure in the carburetor is a little lower.