Fuel Flow Transducer

[Stormy]

We reworked the electrical connections to the transducer and the issue resolved.  I wouldn't have thought that loose electrical connections could have made FF go high.  I am guessing a loose power or signal wire would have flow indication go low - or to zero.  But, a loose ground wire might have been the culprit.  Thanks again for all your comments.  I will continue to watch it, of course.  But, it seems to be working correctly after an hour of operation.  

[PT20J]

32 minutes ago, Stormy said:

We reworked the electrical connections to the transducer and the issue resolved.  I wouldn't have thought that loose electrical connections could have made FF go high.  I am guessing a loose power or signal wire would have flow indication go low - or to zero.  But, a loose ground wire might have been the culprit.  Thanks again for all your comments.  I will continue to watch it, of course.  But, it seems to be working correctly after an hour of operation.  

Curious which connections you reworked. Since you mentioned JPI, I assume you mean the Molex connector where the transducer pigtail connects to the wiring that runs to the engine monitor. The Molex connector is not a very high quality connector and uses tin plated pins. On my 1994 M20J, Mooney used a much better CPC connector which has gold plated pins. You might consider replacing the connector to avoid future problems.

Skip

 

[carusoam]

Great follow-up Stormy...

Thanks for filling in the details...

Best regards,

-a-

[Stormy]

Skip, 

We found knife splices on the three wires coming from the transducer, only a few inches from the transducer.  That is what we reworked.  Wires out of those went to the JPI and the FT101.  But, we didn't touch those.  

Stormy

[A64Pilot]

A flickering loose connection could be counted as a pulse, add that to the pulse rate and you could get a high fuel flow.

It’s a digital system, so you would expect accuracy as each fuel flow meter is tested and calibrated with I believe Stoddard solvent.

But as an example an MVP-50 has as part of its software to auto adjust the K factor, it’s exactly as one poster explained what he did, burn some fuel, the MVP will say I think you burned x amount, you enter the actual amount burned, it says it’s off by xx percent do you want me to apply a correction, you click yes.

Just he did it manually through trial and error

I found after calibrating many of them that the way to really get accurate was to record several tanks of fuel and use the total for it to adjust to, I believe that averaged out any deviations on filling technique etc.

But anyway, if it was a dead nuts accurate digital “thing” say like a hall effect RPM sensor, then EI would not have gone to all the trouble to write software etc so that the system could self calibrate.

So if real accuracy is desired I think adjusting the K factor until it’s close is pretty much a normal thing.

Incidentally on the MVP-50 I would set a power in flight that gave a known fuel burn, then go to the fuel page and manually adjust the K factor, that would get me pretty close and the customer could fine tune it if desired.

These were turbines so no leaning to change fuel flows, but ai don’t see any reason why not to do the same on a Piston.

‘I don’t remember how I did it on my Maule.

Edited July 4, 2021 by A64Pilot

[bgpilot1]

Here are two documents for the FT-101.

Regards,

Barry

hoskins wires.pdf Hoskins_FT101_K-Factor.pdf

[Speed Merchant]

On 7/29/2016 at 3:30 PM, DonMuncy said:

The FF meter in my 231 decided to die. My avionics guru determined it is the transducer that failed. He tells me this is  Mooney part, and has a call in to LASAR. Since my JPI is a secondary only device, we can't tie a JPI transducer into the engine monitor for fuel flow. Until he pointed it out, I was not aware the FF was a necessary instrument, but that appears to be the case.

Anyone have a transducer laying around, know of other sources, or have idea's about alternatives.

Don

I have a working FT -101 with transducer , switch and wire for 70 bucks.  I replaced it with a JPI 930. It worked perfect when it was removed a couple of months ago.

 

[carusoam]

Post date trap….   

-a-

[DonMuncy]

Thanks, but I already solved the problem.

[FredG]

Does anyone know which K-Factor switches need setting with the Hoskins FT101 when installed with the Red cube transducer?

thanks for your help.