Dynon/Advanced Service Bulletin - Kavlico Pressure Sensors

[HFS]

Do a YouTube search for "How It's Made - Oil Pressure Sensors" (5:01) and you will see exactly how the Kavlico P4055 pressure senders are made (Thx Paul). I know because I "disassembled" mine and it looks just like the video.

One thing not mentioned in the video is the "vent" hole at the bottom (inside) of the electrical connector body. The vent hole's purpose is to allow for barometric pressure changes - (G - Series). The "A" series (absolute) do not have this hole.
(Don Jones - Technical Support Manager, Dynon).

This "vent" hole becomes the de facto leak path when there is a failure of the piezo resistive element, and that is what you see in the earlier video posted here - fuel leaking out of the connector body.

Specifications for P4055 Series (what we have): Sensor Type - Piezo Resistive Element, Operating Pressure Range - 0-300psi, Proof Pressure (150psi) - 300psi, Burst Pressure (150psi) - 450psi. Mine tested (to destruction) about 500 psi - so, within spec.

Specifications for P255 Series (recommended change) : Sensor Type - Ceramic Capacitor, Operating Pressure Range - 0-1000psi, Proof Pressure (150psi) - 450 psi, Burst Pressure (150psi) - 2000psi.

The P255 Series offers a significant increase in potential - and, possibly more important, a different sensor medium that may be more resistant to failure from the environment in which they live in our airplanes - as opposed to the ground bound world.

Take the above for what it's worth - but it's what I know from my testing and looking at Kavlico's website.

YMMV

[Bill.Peyton]

The vent hole inside the connector body is a poor design for aircraft useage. I had an issue with my fuel pressure dropping as I climbed in altitude. As it turns out, the o ring seal and the solder sleeves I used to splice to the wires, prevented the pressure equalization hole from seeing the real outside air pressure. This caused the pressure sensor to indicate a decreasing fuel pressure with altitude. I removed the o ring seal and fixed the issue. Kavlico also makes a version of the piezoelectric sensor that has an external vent.
As an aside, I did inspect both of mine and none showed any signs of leakage after 1000 hours or so.
The Garmin SB talks about fuel systems that have a one way check valve holding pressure after engine shutdown implying the pressure may increase due to heating under cowl after engine shutdown.

[Redbud40]

Replacement Sensors
Replacement Kavlico sensors are available for purchase from Dynon. Dynon is not responsible for costs related to the removal and installation of the sensors

So is this normal for experimental for a company to charge for the replacement part that they sold in the first place to use with their product?

[Romeo Victor]

Dear fellow RVer,

I went through this SB a couple of times and would like to know about the correct P/N to order. I tried to contact Don from Dynon four times by email but no answer. Trying to contact them by phone ended on the answering machine.
I'd like to confirm the P/N for the sensors. If I understood the SB correctly, there is only one sensor available to replace the old oil and fuel sensors, you don't offer separate sensors. The mentioned sensor and it's range covers both fluids. Am I right or where is my error in understanding?
The offered P/N P255-150G-EA4 replaces the oil and fuel pressure sensor?

Thanks
Stephan
PH-LRV
RV8
10 hrs.

[Romeo Victor]

Sure, one sensor for each fluid. Self explanatory!
Stephan

[BobTurner]

Originally Posted by Redbud40

So is this normal for experimental for a company to charge for the replacement part that they sold in the first place to use with their product?

The industry standard - experimental or certified - is that the company bears the cost during the warrantee period (typically 1 year). After that time, it?s on the owner. Third party accessories may be included or excluded from the warrantee, read your fine print.

[Jpm757]

I e-mailed Dynon a couple of weeks ago when the SB was released and inquired about 2 upgraded Kavlico sensors (FP & OP). Dan at Dynon called me yesterday and said a limited number were available and they were going through the request list on a first come first serve basis.
I only ordered 1 so as not to be a "sensor hog" as replacing my FP sensor is the most critical to me. I will replace the OP sensor when they are more readily available. By the way the cost was $134.

[Don Jones]

Originally Posted by Romeo Victor

Dear fellow RVer,

I went through this SB a couple of times and would like to know about the correct P/N to order. I tried to contact Don from Dynon four times by email but no answer. Trying to contact them by phone ended on the answering machine.
I'd like to confirm the P/N for the sensors. If I understood the SB correctly, there is only one sensor available to replace the old oil and fuel sensors, you don't offer separate sensors. The mentioned sensor and it's range covers both fluids. Am I right or where is my error in understanding?
The offered P/N P255-150G-EA4 replaces the oil and fuel pressure sensor?

Thanks
Stephan
PH-LRV
RV8
10 hrs.

Stephan,
The 50, 75, and 150 psi sensors (whether oil or fuel) are being replaced with the new style 150 PSI P255-150G-E4A. The 15 PSI sensor used by most carbureted sensors is being replaced by a new style 15 PSI sensor P255A-15G-E4A.

[Redbud40]

I guess the real question than is worn out or broken v defective. Seems like these sensors have been identified as ? not doing what they were designed to do ? ie defective. When a car part goes ? defective ? a recall ensues and you can get a manufacturers replacement. ( usually).
Sure a worn out part I need to replace on my dime but defective?

[David Paule]

My new sensors arrived. The new ones are on top and the original ones on the bottom. Haven't weighed them but the new ones are clearly heavier.

Dynon gave good service, thanks!



So far, none of them have been out of the packages.

Dave