Gmu11 for primary?

[Browncbr1]

I’ve had my dual g5 setup for two years and really like it.  I was just looking on the garmin website to see about software updates and read that when they are connected to a gmu11 ( as I have done) it is certified for primary magnetic compass.      I never realized that before and that’s why I still have my crappy ugly old whisky compass on the steel tube.  If I have complete electrical failure, I still have 4 independent sources on battery for gps ground track.

What do you guys think about removing the ugly whisky compass?    

 

[ArtVandelay]

Just get yourself a panel mount instead:



Tom

[salty]

That doesn't sound right to me. You can replace a DG, but I don't recall anything allowing removal of the mag compass. Can you quote? I'm thinking IFR, maybe you can for VFR?

Edited January 26, 2020 by salty

[gsxrpilot]

Hmmmm... my Aspen is installed with a magnetometer as well. Can I remove the whiskey compass as well? I'd love to get rid of it.

[ArtVandelay]

Hmmmm... my Aspen is installed with a magnetometer as well. Can I remove the whiskey compass as well? I'd love to get rid of it.

I don’t think so, yes you have battery backup of the dual G5s but you only have 1 GMU 11, (and I assume Aspen equivalents) with no battery backup of magnetometer.


Tom

[Browncbr1]

18 minutes ago, salty said:

That doesn't sound right to me. You can replace a DG, but I don't recall anything allowing removal of the mag compass. Can you quote? I'm thinking IFR, maybe you can for VFR?

https://buy.garmin.com/en-US/US/p/570665

 

[bradp]

That doesn’t jive with my recollection of the latest version of the STC IM. 

[salty]

23 minutes ago, Browncbr1 said:

https://buy.garmin.com/en-US/US/p/570665

 

I’m not convinced, but I wouldn’t take mine out anyway. 

Edited January 26, 2020 by salty

[Browncbr1]

11 minutes ago, salty said:

I’m not convinced, but I wouldn’t take mine out anyway. 

 

23 minutes ago, bradp said:

That doesn’t jive with my recollection of the latest version of the STC IM. 

 

50 minutes ago, ArtVandelay said:

I don’t think so, yes you have battery backup of the dual G5s but you only have 1 GMU 11, (and I assume Aspen equivalents) with no battery backup of magnetometer.


Tom

 

 

“G5 can serve as your primary reference source for magnetic heading”

 

is that a false claim on garmin’s website?

 

[gsxrpilot]

The whisky compass is the lest used instrument in my panel, except for the clock

[khedrei]

Primary reference source for magnetic heading in IFR is the HI/DG or HSI. It is not the compass. You cant legally fly IFR without one. The G5 can replace that.  It wont replace a compass. Airliners still have them. I dont think there is any getting rid of it.

I am curious if there is a lot of interference with the panel mounted one?

[ArtVandelay]

 
 
“G5 can serve as your primary reference source for magnetic heading”
 
is that a false claim on garmin’s website?
 

Primary yes, but they are called a “standby compass”. The ? is, are they considered required equipment under the certification rules (CAR 3, or EASA).
There is a lot of magnetic interference in the panel, mostly due to the steel frame.


Tom

[carusoam]

expect a misinterpretation at work...

I think that may be called overselling, on the Garmin website...

We are all using magnetic heading with our HSIs... and DGs...

Connected to a magnetometer is the best way to update the display automatically... even the mechanical displays...

The Mag compass is there for a totally different reason than what Garmin is discussing...

So... in order to remove the mag compass legally... look for something that discusses that separately...

 

As far as I know... my POH has the MELs... the compass is on the list of minimum equipment...

I have used the compass once in 20 years to determine which wasn’t telling the truth... the HSI or the GPS...  the HSI went on holiday... 

I now have several GPS(s) at any one time in my plane, a few clocks too...

But the MELs are the official place to look to see what can be removed and not ground the plane....
 

PP thoughts only, not a mechanic or CFI...

Best regards,

-a-

[ArtVandelay]

FYI, Older planes don’t have a minimum equipment list.


Tom

[khedrei]

Not sure about the FAA but TC has a list of what equipement is required for day VFR, night VFR  VFR OTT, and IFR. Everything on the next higher type of flight simply adds onto the list from VFR. IE everything required for VFR plus ...... everything required for night VFR plus ..... 

The compass is on the very first list.  So regardless of if it's on your required equipement list for your plane or if you even have an equipement list, in Canada you need one. 

[gsxrpilot]

14 hours ago, khedrei said:

Primary reference source for magnetic heading in IFR is the HI/DG or HSI. It is not the compass. You cant legally fly IFR without one. The G5 can replace that.  It wont replace a compass. Airliners still have them. I dont think there is any getting rid of it.

Thanks for the clear explanation. 

[carusoam]

8 hours ago, ArtVandelay said:

FYI, Older planes don’t have a minimum equipment list.


Tom

In that case... we get TOMATOFLAMES...

https://www.m0a.com/required-vfr-day-night-instruments/

Which apparently became Atomatoflames along the way...

PP only....

-a-

[N201MKTurbo]

When I ferried EricJs Mooney to DMs for a pre-purchase inspection, the vacuum pump quit 10 minutes into the flight. I flew it from Phoenix to east Texas with the only heading reference being the magnetic compass. 

Kind of a PITA, but it got me there. Including navigating the Dallas Class B to spend the night at my brother's house.

I did have an iPad and Stratus, but flying looking down at my lap all the time was annoying. It was VFR, I just went old school, got the magnetic compass lined up where I wanted it and picked something on the ground and flew to it. BTW, ground features are harder to come by in west Texas.

[Browncbr1]

Yea I always knew “tomato flames”,

but what I am misled by is that garmin says:

When interfaced with a gad29b and gmu11, “G5 can serve as your PRIMARY reference SOURCE for MAGNETIC heading”....

After looking in the G5 install manual, it says a Magnetic compass may not be removed, but that is regarding the G5 alone.    It isn’t until later in the IM that discussion of the GMu11 interface comes up.    

I guess it is just a blatant false claim then.   

[N201MKTurbo]

18 hours ago, ArtVandelay said:

Just get yourself a panel mount instead:



Tom

You need one of these:

https://www.mcmaster.com/92845a105

 

[201wantabe]

Read the STC and the install manual for the G5 and the GI-275, it clearly states that it cannot replace your whiskey magnetic compass and you are required to have it in order to comply with the STC. When they indicate primary it means you are able to remove your existing HSI, DG or gyro compass.

[khedrei]

9 minutes ago, Browncbr1 said:

Yea I always knew “tomato flames”,

but what I am misled by is that garmin says:

When interfaced with a gad29b and gmu11, “G5 can serve as your PRIMARY reference SOURCE for MAGNETIC heading”....

After looking in the G5 install manual, it says a Magnetic compass may not be removed, but that is regarding the G5 alone.    It isn’t until later in the IM that discussion of the GMu11 interface comes up.    

I guess it is just a blatant false claim then.   

I honestly cant see how you are reading this wrong. A compass is not a primary reference for magnetic heading. The HI/HSI is. The G5 will replace the heading indicator.   I dont see this as a false claim at all. 

[carusoam]

The challenge seems to be more...

What does primary mean... under what conditions?

We have instruments that are primary...

Controls that are primary, for certain phases of flight...  power for altitude, attitude for speed....etc.

Engine instruments that are primary... like CHT, but not EGT...

 

So we use the yoke to control bank and attitude, to maintain level flight and stay on heading...

We use the DG/HSI as the primary instrument for heading.... not the magnetic compass...

We use the mag compass to set/confirm the DG/HSI function prior to flight...

We can use The GMU to support the HSI because twisting a knob every 15 minutes can get for gotten....

 

Just be cautious when...

• interpreting the meaning of primary...
• any marketing group that uses the word primary...

It would be a stretch to say something can be removed because something else is primary and acts in a similar role...

Extra stretchy where time, heading and airspeed are concerned...

Sorry officer FAA...

• I didn’t know my HSI wasn’t set properly...
• I didn’t know how much time elapsed...
• I didn’t know how fast I wasn’t going...

The FAA doesn’t want to allow us to have any easy excuses to run out of fuel, end up in the wrong place, or fall out of the sky...

It will surely mean more work for them... the kind they don’t want...

PP attempt at aviation humor, while discussing the various meanings of the word primary... when used by various people in aviation...

Forgive the marketing people, they know not what they do... and how long their misguided work stays around... 

Best regards,

-a-

[kortopates]

I agree entirely and pilots should know better than to try to assume legal capabilities from marketing materials.


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[N201MKTurbo]

If you look at this AC, you can make a good case that the G5 meets the regs.

https://www.faa.gov/documentlibrary/media/advisory_circular/ac 23.1311-1c.pdf

The magnetic compass is on the TCDS, so replacing it will require a 337 listing the above AC and the G5 STC as approved data.

I would send this all to your local FSDO for their opinion. I was just at the FSDO the other day to get my IA endorsement (I did) I got the impression that they really are there to help you.