Safety Concern with Fuel Press Sender

[TShort]

Tim-

Did you use a different sensor for a reason, or is it what was supplied with your EFIS system? Curious what you are using.

[AAflyer]

Originally Posted by TimO

While I don't have that particular sensor, myself, to piggyback on Lenny's comment, I have the Avistar on my IO-390 and I do know that it holds in fuel pressure with the mixture at idle cut-off. I also have the andair fuel pump. If I park while hot, and I move the mixture off of cut-off, I can hear fuel squirt into the injectors. (when hot, of course) So I know the pressure builds and is retained in that pump-to-servo section of the fuel system.

I haven't ever had an issue, but like I said, I'm using a higher pressure stainless steel sensor. I just never heard the same thing on my IO-540 with a precision system and AFP pump.

Huh...So THAT's what I hear "squirting" under the cowl while I clean the bugs off.

[TimO]

I have an ancient EFIS that uses the Grand Rapids EIS 4000/6000 as my engine monitor. They sell a couple different fuel pressure sensors, one of which is a higher pressure one that was highly recommended to me while I was building back in 2005. So I used that one, and then again on my RV-14 when I installed a similar system in 2015. I don't know the actual sensor maker, but it's a nice sensor and at least on mine I think the entire body is stainless steel.
The current website seems to show a slightly different picture from what I have though.

[clutch22]

On shutdown, my fuel pressure has always climbed out of the upper limit of 50 psi. I wasn't aware that this wasn't normal until I saw the SB. Is there something wrong with my fuel servo? I run an RSA-5AD1.

[olyolson]

Just added this to another post:

I have the legacy sensors for oil & fuel pressure on my engine. Was concerned at first but no leaks since they were installed so I?m leaving them on for now. Advanced Flight Systems will have the new ones in stock in a week or so. I contacted Sansata Technologies in San Diego, the parent company. The new sensor should connect with the snap connectors on top to existing wiring harnesses.

From Sensata:

? This are using a Packard Metripack 150 connection, you should not have any issues connecting the new sensors with the existing harness.?

Regards
Aldo I. Vasquez
Field Application Engineer, North America ? Industrial Solutions



aldo.vasquez@sensata.com || 619-252-7664 mobile
Sensata Technologies, 2320 Paseo de las Americas, Suite 201, San Diego, California 92154

[N319BC]

Originally Posted by rongawer

McMaster-Carr has gauge dampers in both brass and stainless in several sizes, which includes 1/8 NPT. I have found that 0.004 works well for manifold pressure, 0.008 for fuel and 0.015 for oil. The VA-128 is shown with a 0.040" orifice for comparison. The old Kavlico's are brass, the new ones are stainless, and if you are using UMA, which I have, they are stainless as well.
https://www.mcmaster.com/3820K26

Aside from restricting flow in the event of a leak in the sensor, their real purpose is to snub pressure oscillations and provide a nice, stable read out for the monitored system, which these do well.

If you're looking for an alternative, UMA is a solid product and made in Virginia by some really nice folks with a good catalog of sensors. Most of their line is for certified aircraft, so a little more money, but it's a really small cost in the overall budget for what it does.

I just received the gauge vibration damper from McMaster Carr (Item #3820K42) and am now concerned about the diameter of the opening being too small and getting clogged? Anothet concern is will the fuel flow be significantly reduced with the addition of this? Do the benefits outweigh the risks? Just looking for more info to put my mind at ease. That's one small opening.

John

[clutch22]

Originally Posted by N319BC

I just received the gauge vibration damper from McMaster Carr (Item #3820K42) and am now concerned about the diameter of the opening being too small and getting clogged? Anothet concern is will the fuel flow be significantly reduced with the addition of this? Do the benefits outweigh the risks? Just looking for more info to put my mind at ease. That's one small opening.

John

John,
This isn't placed in-line with the fuel flow to the engine, it is on the branched off line going to the transducer only. If I remember correctly, I think my damper is threaded directly into my transducer manifold block. Hope this helps.

[BlackhawkSP]

Originally Posted by N319BC

I just received the gauge vibration damper from McMaster Carr (Item #3820K42) and am now concerned about the diameter of the opening being too small and getting clogged? Anothet concern is will the fuel flow be significantly reduced with the addition of this? Do the benefits outweigh the risks? Just looking for more info to put my mind at ease. That's one small opening.

John

The damper is to be installed (just to be sure) in the "Teed" off line to the pressure sensor block. The small orifice opening will dampen vibrations/pulses to the sensor (good thing), and will reduce the flow rate of any possible leaks. This is totally separate from the flow to the engine.

[N319BC]

Clutch22 & BlackhawkSP,

Thanks for the clarification. I would have installed this inline with the Kavlico sensor, thinking that was the most logical place to reduce the vibrations/pressure. Is the damper then capped off once attached to the block?

john

[rongawer]

Originally Posted by N319BC

Clutch22 & BlackhawkSP,

Thanks for the clarification. I would have installed this inline with the Kavlico sensor, thinking that was the most logical place to reduce the vibrations/pressure. Is the damper then capped off once attached to the block?

john

Let's be clear, the vibration damper, which is essentially just an in-line orifice, is installed in a sensor line, not the main line. For a fuel line, you would have a sensor line Tee off of the supply line, or a separate line from a fuel block, if you have one. That sensor line would have the damper and end with the sensor. You could thread the sensor directly into the damper at the end of the sensing line as an option. The whole point is to dampen pulse oscillations to the sensor with the benefit of restricting flow rate if the sensor were to burst.

I want to point out that the sensor line is a static column of fluid with essentially no flow once filled, so the odds of it becoming clogged are somewhere between very low and improbable.