JPI EDM 930 and fuel senders

[chrisb]

I am planning to buy JPI EDM 930. Any recommendations on that? Have a question regarding fuel senders: do I need to replace them?

Does anyone have problems with EDM 930 fuel quantity reading? Thank you

[Houman]

I don't have a 930, would love to have one, but I can tell you that JPI tech support is amazing imho, they answer all your questions pretty quickly and a real person. I asked the same question a while back when I was looking at the prices. I have a hoskins 101 Fuel Flow transducer and they told me that I just had to configure the K factor according to what I had and it should work no problem.

 

So most probably in your case as well, no need to change the senders, but check with them 1st.

[FloridaMan]

I have the EDM-900. It uses the stock sensors and therefore the fuel level indications on the EDM are no more accurate, even when calibrated, than the factory gauges. The fuel flow, however, appears to be spot-on with fuel used. I always look in my tanks before every departure and I have the dial gauges on the wings that I look at in flight, just to make sure something isn't happening where all the fuel is running out and now I have the JPI to tell me exactly how much fuel I've consumed. 

[Bob_Belville]

I have had an EDM 930 since 2012. I like it a lot. The large screen can be mounted on the right side of the panel and still be easily seen and interfaced with. Their customer service has been fine. I had to send the unit and the transducer back to the factory dealing with erratic fuel pressure. They found nothing wrong, updated my software and return in about 2 days.  

 

I agree that fuel quantity displayed is only as good as the senders which is not great. They are only required to be correct when the tank is (near) empty. Mine are quite accurate when qty is 10 gal or less. But the key to safe fuel management is the extremely accurate fuel flow sensor/accumulator.

[chrisb]

Thanks everyone! Has anyone had problems with EDM 930 showing erratic reading of fuel quantity? 

[Bob_Belville]

Thanks everyone! Has anyone had problems with EDM 930 showing erratic reading of fuel quantity? 

The fuel qty may vary, particularly when tank is over half full, but I doubt the problem is in the 930. 

[M20F]

I have an EI MVP-50 and the totalizer works great. The individual tank gauges are the same as the analog ones, fairly useless once they burn down. I would guess your experience will be the same. I have been very happy with my EI unit for 3yrs now.

[Vance Harral]

They are only required to be correct when the tank is (near) empty.

 

Really wish people would stop propagating this misinformation.  The certification standards for fuel gauges (FAR 23.1337( b ) for newer airplanes, CAR 3.672 for older ones) include a requirement for them to read zero when remaining fuel is equal to unusable fuel.  But they most certainly don't allow the gauge to be inaccurate at other points across the range.  For more info, see http://www.av8n.com/fly/fuel-gauges.htm

 

If you're flying an airplane whose fuel gauges are grossly inaccurate at any fuel level, it's not legally airworthy and needs to be fixed.  As a realist, I appreciate there is some discretion in accuracy, and in making "test flights" to debug indication problems.  But telling other pilots that fuel gauges are only certified accurate when empty is like saying the tachometer only has to be accurate when the engine isn't running.  It's not at all true, and encourages people not to fix something that is actually broken.

[Bob_Belville]

Really wish people would stop propagating this misinformation.  The certification standards for fuel gauges (FAR 23.1337( b ) for newer airplanes, CAR 3.672 for older ones) include a requirement for them to read zero when remaining fuel is equal to unusable fuel.  But they most certainly don't allow the gauge to be inaccurate at other points across the range.  For more info, see http://www.av8n.com/fly/fuel-gauges.htm

 

If you're flying an airplane whose fuel gauges are grossly inaccurate at any fuel level, it's not legally airworthy and needs to be fixed.  As a realist, I appreciate there is some discretion in accuracy, and in making "test flights" to debug indication problems.  But telling other pilots that fuel gauges are only certified accurate when empty is like saying the tachometer only has to be accurate when the engine isn't running.  It's not at all true, and encourages people not to fix something that is actually broken.

I do not believe the floats in our Vintage Mooney tanks can discern the top several gallons due to the dihedral and the short sensor arm. I will verify my previous statement which I think was made by a very conscientious shop.

[Vance Harral]

I do not believe the floats in our Vintage Mooney tanks can discern the top several gallons.

 

Fair point.  I can only speak for the floats in our 1976 F model.  They're on the outboard side of the tank, and there isn't much difference between their location and the end of the tank, so I think the error is small.  Other Mooneys and other brands are different, of course.  The dihedral on the hershey-bar-wing Cherokees seems especially aggressive to me, and now I wonder about their fuel sender design.

 

But even if there are "several" (shall we say 3?) gallons of error, that's about a 10% error on a roughly 30-gallon tank, which will go away after about 20 minutes of flying on the tank in question.  Hardly the same as saying the fuel gauges are only accurate at the empty mark.

 

 

I will verify my previous statement which I think was made by a very conscientious shop.

 

Sounds to me like the shop just doesn't want to work on the senders.  Not suggesting it's because they're not conscientious.  More likely they know most customers would blow a blood vessel if they saw a bill for a no-apologies fix, and they figure other methods of tracking fuel quantity are safe enough.

 

If you want the straight story, though, tell them you're arguing with some guy on the internet , and can they please cite the regulation that says the fuel tanks only have to be accurate at the empty mark.  I'll bet a nickel they've never read CAR 3.672 or any of the references cited in the link I gave.

[Bob_Belville]

Fair point.  I can only speak for the floats in our 1976 F model.  They're on the outboard side of the tank, and there isn't much difference between their location and the end of the tank, so I think the error is small.  Other Mooneys and other brands are different, of course.  The dihedral on the hershey-bar-wing Cherokees seems especially aggressive to me, and now I wonder about their fuel sender design.

 

But even if there are "several" (shall we say 3?) gallons of error, that's about a 10% error on a roughly 30-gallon tank, which will go away after about 20 minutes of flying on the tank in question.  Hardly the same as saying the fuel gauges are only accurate at the empty mark.

 

 

 

 

 

Sounds to me like the shop just doesn't want to work on the senders.  Not suggesting it's because they're not conscientious.  More likely they know most customers would blow a blood vessel if they saw a bill for a no-apologies fix, and they figure other methods of tracking fuel quantity are safe enough.

 

A 66' E with 26 gallons in each wing have floats in the tanks that pivot at the cabin wall end. The arm is probably 12" so the float will be pinned to the top of the tank until a significant amount of fuel is remove. The installer carefully added fuel 1 gallon at a time to calibrate the JPI.

 

If you want the straight story, though, tell them you're arguing with some guy on the internet , and can they please cite the regulation that says the fuel tanks only have to be accurate at the empty mark.  I'll bet a nickel they've never read CAR 3.672 or any of the references cited in the link I gave.

Vance, guess again. My 930 was part of a 50+AMU new panel done by an avionics shop. They are also A&Ps and this is the log entry for the relevant non avionics work they performed:

 

"Removed right magneto, replaced gasket, reinstalled mag, retimed mag (20 BTC rcb) Complied with AD 77-17-04 by performing Mooney SB M20-205B. Removed fuel sender PN :5641991 SN: 123868 and PN:610242-001 SN: 123867 and reinstalled after overhaul by Airparts of Lock Haven. Replaced Rapco "donut" vacuum filter PN: RAB-3-5-1 with new. Installed Garmin power/data cable PN:010-11206-15.Replace broken light tray on turn coordinator with new. Replaced inop UMA suction gauge PN: 3-200-12 with new. Installed co-pilot PTT switch. Drained oil, replaced oil filter with new AA48110-2. Filled w 7 qts Aeroshell W100."

 

I assure you they cut no corners and that while doubling my cost basic in my now 50 year old E, repairing the floats and senders was just round off chump change.

 

While upgrading my panel they discovered that a mag was out of timing, that the alternator bearing was going bad, that eyebrow lights were burnt out and several other items that were not their problem.

 

They had the plane 9 weeks. I did not have a single call back squawk. The GLD88 had not been released by Garmin in Dec. 2012 when the plane was ready so the shop pre-wired for it and I went back to get it 6 weeks later.   

 

Here's what Ms. Google found:

 

The relevant part of the aviation regulations is as follows - make of it what you will: (FWIW, with over 2500 hours in Mooneys I make it a policy to land with at least an hour's fuel on board. I once make an unplanned fuel stop and added 50.2 to 52.0 usable capacity when a tank coughed dry reading over 1/4 tank 25 miles from my intended destination. Anyone who trusts a Mooney fuel gauge is... choose your favorite fool synonym.)  

 

§ 23.1337 Powerplant instruments installation.

     Fuel quantity indication. There must be a means to indicate to the flightcrew members the quantity of usable fuel in each tank during flight. An indicator calibrated in appropriate units and clearly marked to indicate those units must be used. In addition: [] Each fuel quantity indicator must be calibrated to read "zero" during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply. . . 

[Vance Harral]

Thanks for the reply, Bob.  Sounds like your shop is very diligent.  Glad you found a good one.

 

I don't want this to turn into a debate about trusting the fuel gauges as a sole indicator of fuel status.  No one seriously argues this is acceptable.  However, pilots should insist on reasonably accurate gauges because they're an important component of a multi-point approach to fuel management.  The gauges are the only way to catch an in-flight fuel leak (loose gas cap, wet wing/bladder leak, fuel selector valve went bad, fuel hose clamp came loose, etc.)  If you miss a fuel tank switch, they're the only thing that might clue you in before the engine quits.  Neither a fuel totalizer nor the tried-and-true stopwatch method will catch these kinds of problem, which really do cause bent metal and/or dead aviators.  I have a story about my own experience with this - which is why it's a hot button item for me - but I'll save it for another time (nothing too spectacular, it involves a simulator ride).  Anyway, you should expect accurate fuel gauges for the same reason you expect every flight instrument in your six-pack to be accurate: each one has a failure mode that's detectable only when considered in the context of data from other instruments.

 

Assuming you agree with that point, let's talk about what's reasonable to expect from a properly operating system.  You found the certification reg yourself (it's the FAR 23 version, but the CAR 3 version under which your airplane was certified is essentially identical):

 

§ 23.1337 Powerplant instruments installation.

     Fuel quantity indication. There must be a means to indicate to the flightcrew members the quantity of usable fuel in each tank during flight. An indicator calibrated in appropriate units and clearly marked to indicate those units must be used. In addition: [subpart 1] Each fuel quantity indicator must be calibrated to read "zero" during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply. . . 

 

The bolded portion above says the indicator must be calibrated in appropriate units.  Period, full stop.  No reasonable person would argue "calibrated" only applies to the zero level, and no DER would certify a design with gross errors everywhere except empty.  People who think the gauges only have to be accurate at empty either misunderstand subpart ( 1 ) - an additional clause which only clarifies the meaning of zero with respect to usable vs. unusable fuel - or they're repeating something they heard, without actually reading and understanding the regulation.  If you disagree, consider FAR 23.1323 ( b ), which governs the accuracy of airspeed indicators.  That regulation only specifies a calibration error range above 1.3*Vs1, but no one says, "You know, that airspeed indicator only has to be accurate above approach speed."

 

I think the reason this misunderstanding has so much traction is it's a self-fulfilling prophecy.  Operators and mechanics tell other operators/mechanics that brand new, properly installed gauges and senders won't perform any better than the dysfunctional, worn out ones they already have.  So unlike tires and brake pads and other components with practical life limits, they don't get replaced.  More and more pilots are then exposed to airplanes with malfunctioning fuel gauges (particularly with the aging airplane fleet), and a preponderance of pilots come to assume it's normal, despite it being entirely antithetical to both the letter and the spirit of the certification regulation.  Unfortunately, it's just one of those things that "went viral" way before that saying even had meaning.

 

Finally, in emphasis: I am not arguing the gauge/sender design is particularly robust or reliable (indeed, I'm well aware they're a PITA to maintain), nor am I saying it's OK to use the gauges as a sole indicator of fuel status.  I'm saying that people who think fuel gauges are never intended to be accurate except at empty are misinformed.

[FloridaMan]

 

Aside from that, if you're concerned over monitoring fuel level, I've found the dial gauges in the wings to be far more accurate in flight than any sender/panel instrument combo for measuring level. 

[Bob_Belville]

<snip>

 

Finally, in emphasis: I am not arguing the gauge/sender design is particularly robust or reliable (indeed, I'm well aware they're a PITA to maintain), nor am I saying it's OK to use the gauges as a sole indicator of fuel status.  I'm saying that people who think fuel gauges are never intended to be accurate except at empty are misinformed.

Fair enough. It seems to me that the fact that while calibration in pounds, liters, gallons is to be done for the whole range of the scale apparently there is no stated standard for precision. The last line about reading zero is really a comment on how to treat unusable fuel with the stipulation that the gauge represents only usable fuel qty to ward off any ambiguity and isn't a statement about acceptable +/- tolerances either. I concede your scenarios can occur and bite you even with precision fuel flow. But I reiterate that the only time I had a fuel starvation scare was while trusting a fuel gauge. That was on November 9, 1970 in a M20G rented @ 8A6. It's been 45 years but I still remember the 50.2 gallon fillup at KEOE. I had 175 hours at the time, probably 100 in Mooneys. I doubt I've ever landed with less than 1 hour's fuel on board since. Lesson learned.

[fuellevel]

I think the reason this misunderstanding has so much traction is it's a self-fulfilling prophecy.  Operators and mechanics tell other operators/mechanics that brand new, properly installed gauges and senders won't perform any better than the dysfunctional, worn out ones they already have.  So unlike tires and brake pads and other components with practical life limits, they don't get replaced.  More and more pilots are then exposed to airplanes with malfunctioning fuel gauges (particularly with the aging airplane fleet), and a preponderance of pilots come to assume it's normal, despite it being entirely antithetical to both the letter and the spirit of the certification regulation.  Unfortunately, it's just one of those things that "went viral" way before that saying even had meaning.

Finally, in emphasis: I am not arguing the gauge/sender design is particularly robust or reliable (indeed, I'm well aware they're a PITA to maintain), nor am I saying it's OK to use the gauges as a sole indicator of fuel status.  I'm saying that people who think fuel gauges are never intended to be accurate except at empty are misinformed.

Well - the world has changed.   New fuel quantity systems have to meet a performance Standard the three newest for OEM aircraft (Cirrus G5, Cessna 172 thru Caravan, Piper M Series Update)  are TSO'd  designs (demonstrated  standard of performance).   As Vance indicated the FAA is concerned that the fuel quantity system provide accurate level information throughout the flight (Straight and level).   They were very concerned with Cessna on the as early as the 1995 startup - Cessna calibrated each resistance sender to the aircraft.    The largest change was to lightning and spark effects internal to the tank. 

Advisory Circular 23-17 SYSTEMS AND EQUIPMENT GUIDE FOR CERTIFICATION OF PART 23 AIRPLANES AND AIRSHIPS 

1. Digital fuel flowmeters are not a required powerplant instrument except for turbine engine airplanes with an Amendment 23-43 certification basis. They are optional equipment and should not be considered replacements for fuel quantity or fuel pressure indicators. 

Overall accuracy for fuel remaining and time remaining readings depends on the transducer processing unit and display. The largest possible error is the initial fuel supply, which is entered by the pilot at the start of each flight. Errors in the initial fuel supply may be caused by an uneven ramp, unusual loading, volume changes of the fuel because of temperature variations, malfunctions in the fuel system such as leaks, siphoning actions, collapsed bladders, and other factors.  So, total fuel remaining should be verified with the fuel quantity indicator.  According to § 23.1337(b)(1), fuel quantity indicators are required to be calibrated to read "zero" during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply.  Therefore, fuel quantity indicators should be used as the primary fuel-remaining instruments. Fuel quantity indicators that are inaccurate should be periodically calibrated, repaired, or replaced, as necessary, to ensure reliable readings. 

In fact this is actually required for Australian aircraft every 4 years. 

0. A placard should be near the fuel flowmeter/fuel totalizer display with the following statement: “Original equipment fuel quantity indicator is the primary reading of fuel on board the airplane.”  

It appears that the FAA is not on the same page as the rest of aviation .... However when you read the FSDO Documents, they paint an entirely different picture 

as does the Hazard Analysis of AC 23.1309 

However they admit that bad information is no hazard - see image  - I don't know if that holds water 

 

Edited September 30, 2015 by fuellevel

[wishboneash]

I am planning to buy JPI EDM 930. Any recommendations on that? Have a question regarding fuel senders: do I need to replace them?

Does anyone have problems with EDM 930 fuel quantity reading? Thank you

Before putting in the JPI-930, I would recommend the fuel senders be overhauled at Air Parts (Lockhaven, PA) telling them you would be using this in conjunction with this engine monitor.

[fuellevel]

We can supply TSO'd senders for Mooney Aircraft - newer than L model.    It would require a 337 for install.   While we are an OEM systems for several manufacturers,  we have been helping out the Bonanza / Baron, Cirrus and Cessna 177 crowd.   We have a design for the Mooney late model aircraft.  It is a powered sensor - but has been proven.  At present the new Cirrus fleet (newer than 2012) has 300,000 hrs plus without a fuel sender replacement.  Let us know.  I believe we are competitive with rebuilt for a sender that plugs into the same location with a contactless technology.

I wasn't there to witness it, but Bill at Green Mountain Avionics reports that my fuel quantity calibration on the EDM 930 is complete.
There were a number of opportunities during the entire process for you to provide information and technical assistance, and to your great credit, you were there EVERY STEP OF THE WAY!!  
Yesterday provided yet another opportunity for you to help out, as my fuel tanks apparently held a bit more fuel than expected. I know Bill conferred with you and JPI both about how to properly calibrate the senders given this unexpected turn, and in usual fashion, you helped provide clarity in an unclear situation.
So to any fellow BT'ers considering the CiES senders, solely based on Scott's dogged determination to "get it right" for the customer, I'd encourage you to pull the trigger. I guarantee that Scott and CiES won't disappoint.
jh

[carusoam]

FL,

Feel free to leave your contact information and website.  We appreciate your knowledge and support.

Best regards,

-a-

[fuellevel]

It is  CiES Inc Website  

I can be reached at Email Address

The system is magnetic field - similar to your cell phone compass - No matter how how shake and move your cell phone - North is North - for us  - The fuel surface is the fuel surface.

CiES inc. holds the patent for utilizing the technology in this video to measure fuel level https://youtu.be/ww3IsROsbwc .  The technology is used in high reliability automotive systems like steer by wire, brake by wire, throttle by wire and stability control.

We have the simplest, most reliable  and the most accurate fuel level solution for new aircraft - no other system even comes close   - and in true aviation form we are glacially taking over the fuel quantity business on piston, turboprop, and business jets.     

The most surprising thing is that we use a float to do it. 

Edited September 30, 2015 by fuellevel

[carusoam]

Scott,

256 discreet outputs from filled up, down to empty sounds pretty good.

My analog system is somewhere near a scale of 0-25, Empty to full.  I am currently using a FT101 FF meter for observing my fuel flow and gallons used.  The mechanical float gauges in the wing in combination with what the Fuel Truck says are used for filling my tanks properly.

I won't be going digital for a while. JPI 900 or similar is on the wish list. Then a bunch of new sensors will be on the wish list to match.

It is nice to have you aboard.

Best regards,

-a-

[fuellevel]

Actually,  we have 566 data points per sender available with the new configuration.   So the Mooney has about 750 or so data points to describe the tank vs. the 75 or so available in a resistive sender.    We will have that same 750 data points 20 yrs from now  - the resistive - would be down to your 25 or so and they might not be linear. 

This fuel quantity project started at Mooney and was proven there,

It is a natural fit - exciting times ahead for Mooney

 

[fuellevel]

Here are the late model Mooney senders - these will plug and play with any MFD  (JPI 900, EI, Auracle, Aerospace Logic)  they will plug and play digitally with a JPI 930, Aerospace Logic or a Garmin G1000, G950 (With a configuration change).    Digital is the way to go if you can.    We can output to a standard gauge - but I really don't feel that that is the market for advanced fuel quantity senders.     

These senders are the best technology available for aircraft, which for some seems counterintuitive because we use a float.   We are replacing "Capacitive" fuel quantity systems at the OEM level as we perform better and are far more reliable.   The float actually makes the system better as it dampens small variations in fuel level.   The real difference was the non-contact sensor system.

http://fuellevel.blogspot.com/2015/10/the-cies-is-better-than-aircraft.html

Edited October 3, 2015 by fuellevel

[carusoam]

Nice explanation of the K factor and why our ordinary FF gauges are so accurate over varying temperature changes.

Does my FT101 know what temperature my fuel is?

Does the CIES fuel level sensor notice or compensate for a difference in fuel temperature?

Thoughts that come to mind based on reading the above link.

Best regards,

-a-

Edited October 3, 2015 by carusoam

[Marauder]

What does a set cost for a Mooney?

Sent from my iPad using Tapatalk

[fuellevel]

The article was to show how we are measuring fuel in contrast to a capacitive system - For our system we don't need to compensate for temperature.

We do have a fuel temp output that can be specified if you want it or are an OEM with Jet A.   Jet A tends to go to jelly when it gets real cold.  

Or equally if you are interested in it to get lbs fuel for weight and balance reasons.   You would have to have an instrument that would calculate this 

 

At present we are selling them at $390 each - that's for a FAA TSO Sender - but no STC - 337 Field Approval required  so rough order of magnitude 1.6 AMU.