M20K 231 - fitting an engine monitor

[carusoam]

On the JPI900... expect the fuel level to be primary...

1) Now... where that is stated... and what words they use to say that... Check the JPI website and read the differences between the 900 series and the 800 series... very similar devices, only one has more primary functions than the other... same challenge for the other manufacturers... only some functions  May be primary...

2) The POH has the required instruments for flight... a chart that covers VFR, IFR, Day, Night...  if the box is checked on the list... it is required... Again back to JPI for the list of primary functions...

PP thoughts only, not a mechanic...

Best regards,

-a-

[tmo]

@carusoam - that's my point :-) looking at the JPI docs: JPI EDM-900 AFM supplement for example I see no mention of either FUEL LEVEL being "primary" (see page 3).  It does list "AMPS" and "Estimated Remaining Fuel" (which I guess is what the factory gauges display) as "non-primary" so I wonder what is the basis of being able to remove the original gauges from the plane, as people obviously do.

I understand that the RPM/MAP/CHT/Oil Temp/Oil Pressure/TIT/CDT are all "primary" so that's good and clear, but how does the fuel and the current (AMPS) get handled?

I am, for the time being, leaving all the original gauges, so I'll be legal, just don't want to miss something and have to go back to JPI or, worse, be stuck with not-exactly-what-I-wanted for the $5k + installation.

EI lists both "AMPS" and "Fuel level" as a "primary replacement" on their CGR30-P/C combo.  They also list "fuel remaining" as a "non-primary" indication, which leads me to believe the two (fuel level and remaining) can are technically (from a paperwork perspective) not the same thing.

[jlunseth]

At least for us here in the US, the place that required equipment is listed is in the Type Certificate for the aircraft. The TC for the Mooney’s is available online, you have to look at the correct model number and in some cases, aircraft serial number.  Do a google search for “Mooney type certificate,” I think that will do it.  Off-hand, I don’t know what the 231 TC says about the amp gauge.  The documentation you would refer to, in order to determine whether a particular readout for the JPI is certified as primary, is not the product documentation, it is the Supplemental Type Certificate.  It has been years since I have looked at that, but I am fairly certain the 930 is STC’d as primary for the fuel gauges and for a number of other things.  You should have an STC in your aircraft documents, and if you do not you can find it on JPI’s website as I recall, or get one from JPI.

How this works in Poland though, I don’t know.

[jlunseth]

I went on the JPI site.  The Fuel Level is listed in the AFM as being a primary replacement.  AFM Rev. 930-0001 Rev. D. The revision table indicates that the AFM was revised in 2016 to add “Fuel Level Analog or Analog/Digital”. A call to JPI to verify the authorization would not hurt.

 

https://www.jpinstruments.com/wp-content/uploads/2012/08/930AFM-D-3-28-2016-FAA.pdf

Edited December 13, 2019 by jlunseth

[tmo]

The plane is N-reg, so FAA rules apply.

I went through the whole AFMS for the EDM-900 and it does indeed mention that the unit "may replace any existing .. Fuel Quantity indicators required by the aircraft type design" in the "Operating Limitations" section on page 6.  Too bad they didn't bother to update the "primary / non-primary" table on page 3...

But the good news is it seems to all be as advertised.  Thank you for the suggestion to read all of the fine manual, not just skim it.

[kortopates]

The plane is N-reg, so FAA rules apply.
I went through the whole AFMS for the EDM-900 and it does indeed mention that the unit "may replace any existing .. Fuel Quantity indicators required by the aircraft type design" in the "Operating Limitations" section on page 6.  Too bad they didn't bother to update the "primary / non-primary" table on page 3...
But the good news is it seems to all be as advertised.  Thank you for the suggestion to read all of the fine manual, not just skim it.

They also show fuel levels in the "primary area" of the display - where all primary approved items are displayed. Depending, it's not practical or possible to keep your OEM gauges with your JPI. For example, you can't install the digital CIES fuel senders and connect them to your Mooney, nor can you either install both your oem oil pressure sensor and the JPI oil pressure and temp sensor - they are different probes and there is only one primary approved location.

Fuel remaining is different from fuel level indicated by fuel senders. It's merely a calculated value based on starting fuel you input, after adding fuel or filling the tanks, and fuel flow in GPH. Fuel flow is the important one and it's primary as well.


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[FloridaMan]

If you can swing it, try to avoid putting an EDM-900 on the right side of the panel. The reason is that it requires a remote warning light in front of you. If any instrument hits redline, you get a blinking red light in front of you that says ENGINE. I had this issue with my M20F for when things were in normal operation. Stock fuel pressure gauge calibration red line was 30 psi, but Lycoming's limit is 45 and mechanical fuel pumps now run just shy of 30psi except when you pull power or idling you get this warning light. Same goes for if the prop stays at exactly 2700 RPM for more than a couple seconds. On the rocket, the EDM-900 simply displays the value in red without requiring me to be distracted by the ENGINE light to identify and clear a warning. 

[tmo]

It will go in the left panel.  With 90% certainty it will be portrait (I only loose the individual CHT/EGT temps from what I can tell) in the rightmost "lane" - AP annunciator will go up a slot, ADF removed, CDI moved to where ADF is.  The other 10% is that both ADF and backup AI get removed, CDI replaces AI, EDM goes horizontal where the CDI now is.