AHRS failure on the 172s G1000.

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Bereikua

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Bereikua
Hello everybody!

A couple of months ago this happened during an instruction flight.

sobvhns.jpg


lQMhK8l.jpg


Do any of you know why? I haven't found anything on the POH. Is it common?

We were on short final after making a slip (possible cause?).

It went back ok before we reached the parking.

Thank you!
 
Welcome to POA! Your post was in moderation because you added attachments or links as a new member. But I approved it and hope someone has some answers for you.
 
I've flown a G1000 exactly once... on a discovery flight. We had an AHRS failure, too. Considering it was a VFR flight on a VFR day, it really didn't matter. We ended up having to cycle the avionics to get it back in the end.
 
Get it in the shop ASAP! That is not normal. Does this aircraft have dual AHRS? if so, did you lose that as well?


edit: btw, why the heck are you only doing 47 knots on final?
 
Some how the AHRS is getting confused. Amps are yellow on right bus? Did you turn off all electronic devices?:) It might have given up when you couldn't find the localizer.
 
Definitely not normal; I've never had an AHRS failure in the handful of years I've been flying with 'em.

I would think that with the GRS 77 being an LRU, it should be able to be replaced with a working loaner without much of a headache while it get's a checkup from a doctor, so you can keep the bird flying. (But I'm not an avionics guy, so it's really just speculation...)
 
G1000_system_block_diagram.JPG


Fly your standby instruments and get the LRU replaced on the ground.

It reminds me of my instrument checkride in the sim - AHRS failure on the PT outbound. Partial panel on a non-precision approach with DME step downs using compass turns to minimums. That's a weird scan, let me tell ya.
 
Spent the past hundred hours flying a G1000 C172 and never saw that happen.
 
My G1000 172 has always been rock solid. Well, except for the time it wouldn't power on. That was a faulty avionics switch. I flew a 2-hour flight on backup instruments and no transponder!
 
Not the 1st time I have heard of this with a G1000.

Not the 1st time I have heard of it with other manufacturers EFIS's, even current generation dual AHARS with both AHARS failing concurrently.

I have personally had an old non-current generation EFIS roll inverted just 50 feet AGL in IMC on takeoff.

Be careful out there. Have backups which are realistically able to be used in event of shiny pretty EFIS screen going tits up at the most inopportune moment.
 
I've seen the G300 AHRS lose its marbles (PFD looked like an aileron roll while I was S&L). I covered it up with a sectional and FTFA. The POH has a reset procedure.

Geico266 said:
It is my understanding these "failure events" must be reported to the FAA.
Click to expand...

Reference?
 
Why is the MFD off? Besides not seeing the MFD on in your photo picture, the tell tale other sign is that the engine parameters are on the PFD.

I've had the AHRS fail if there is excessive vibration but it then resets itself within 20 seconds or so while displaying that message "AHRS ALIGN: Keep wings level" that you are also seeing. Your indicated speed is a little on the low side while you're snapping pictures and otherwise distracted by the G1000 acting up... You need to watch out for that.
 
GeorgeC said:
Reference?
Click to expand...
Incident and accident reporting criteria in CFR Part 49 830.5 (a)(9).
Summary: You must report as soon as possible any failure of type:
"(9) A complete loss of information, excluding flickering, from more than 50 percent of an aircraft's cockpit displays known as:
(i) Electronic Flight Instrument System (EFIS) displays;"

I don't know if this failure meets this criteria but until Geico substantiates his comment I suspect this is what he's thinking of.

Nauga,
and the BSOD
 
It looks like it rebooted the AHRS for some reason. First thing I would do is make sure all the plug in connections on the boxes are all secure.
 
nauga said:
Incident and accident reporting criteria in CFR Part 49 830.5 (a)(9).
Summary: You must report as soon as possible any failure of type:
"(9) A complete loss of information, excluding flickering, from more than 50 percent of an aircraft's cockpit displays known as:
(i) Electronic Flight Instrument System (EFIS) displays;"

I don't know if this failure meets this criteria but until Geico substantiates his comment I suspect this is what he's thinking of.

Nauga,
and the BSOD
Click to expand...


He didn't lose the display. He lost the AHRS. The display is fine. It's reporting the failure.
 
Everskyward said:
He didn't lose the display. He lost the AHRS. The display is fine. It's reporting the failure.
Click to expand...

The reg refers to "loss of information" which comes from a display, which is what happened here.
 
RotorDude said:
The reg refers to "loss of information" which comes from a display, which is what happened here.
Click to expand...
I read the reg differently than that. The display is showing information. The information is that the AHRS is failed.
 
Everskyward said:
I read the reg differently than that. The display is showing information. The information is that the AHRS is failed.
Click to expand...

I agree that the wording can be improved, but I think what they mean is that "information" is the normal status of the aircraft. Otherwise, one could argue that even if all instruments fail, you still have "information" that they have failed by virtue of seeing them all dead.
 
RotorDude said:
I agree that the wording can be improved, but I think what they mean is that "information" is the normal status of the aircraft. Otherwise, one could argue that even if all instruments fail, you still have "information" that they have failed by virtue of seeing them all dead.
Click to expand...

Do you have to report the loss of a single flight instrument in a six pack? Apply the same level of logic to the glass.
 
RotorDude said:
I agree that the wording can be improved, but I think what they mean is that "information" is the normal status of the aircraft. Otherwise, one could argue that even if all instruments fail, you still have "information" that they have failed by virtue of seeing them all dead.
Click to expand...
I think the reg is addressing the integrity of the displays themselves or they would not exclude "flickering" as a condition you need to report. You would need to report if more than 50% of the screens were unreadable, for instance if they went black.
 
Henning said:
Do you have to report the loss of a single flight instrument in a six pack? Apply the same level of logic to the glass.
Click to expand...

I assume we are talking about IFR flight, in contact with ATC.

5-3-3. Additional Reports

a. The following reports should be made to ATC or FSS facilities without a specific ATC request:

1. At all times.

...

(h) Any loss, in controlled airspace, of VOR, TACAN, ADF, low frequency navigation receiver capability, GPS anomalies while using installed IFR-certified GPS/GNSS receivers, complete or partial loss of ILS receiver capability or impairment of air/ground communications capability. Reports should include aircraft identification, equipment affected, degree to which the capability to operate under IFR in the ATC system is impaired, and the nature and extent of assistance desired from ATC.

NOTE- 1. Other equipment installed in an aircraft may effectively impair safety and/or the ability to operate under IFR. If such equipment (e.g., airborne weather radar) malfunctions and in the pilot's judgment either safety or IFR capabilities are affected, reports should be made as above. 2. When reporting GPS anomalies, include the location and altitude of the anomaly. Be specific when describing the location and include duration of the anomaly if necessary.
Click to expand...

One could argue that loss of AHRS or gyro equipment may "impair safety and/or the ability to operate under IFR", even if there is a backup primary gauge.
 
RotorDude said:
I assume we are talking about IFR flight, in contact with ATC.



One could argue that loss of AHRS or gyro equipment may "impair safety and/or the ability to operate under IFR", even if there is a backup primary gauge.
Click to expand...

Those reports are different than the accident and incident reports you need to make under CFR Part 49 830.5.

Maybe it would be clearer if the whole relevant passage is quoted.

(9) A complete loss of information, excluding flickering, from more than 50 percent of an aircraft's cockpit displays known as:
(i) Electronic Flight Instrument System (EFIS) displays;
(ii) Engine Indication and Crew Alerting System (EICAS) displays;
(iii) Electronic Centralized Aircraft Monitor (ECAM) displays; or
(iv) Other displays of this type, which generally include a primary flight display (PFD), primary navigation display (PND), and other integrated displays;
Click to expand...
 
Everskyward said:
Those reports are different than the accident and incident reports you need to make under CFR Part 49 830.5.

Maybe it would be clearer if the whole relevant passage is quoted.
Click to expand...

Yes, I was thinking about ATC reports during IFR flight, not accident/incident reports. Thanks for pointing me straight. :)
 
First off I have never had that happen in either of the G1000 172's I fly..

My questions from the blurred pictures are as others have pointed out,
why are you doing 47-50kts?

Why in the engine RPM at exactly 1000, ( when I'm descending it never gets that low even with an idle power setting)?

why is the main amp bus have a negative state and why in the back up yellow ??
 
If you descended at 50 knots, you might get that 1000 RPM.

This looks like an electrical failure in progress. Maybe that's why the AHRS failed.
 
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Thank you for all the answers guys.

ferrari-tech said:
First off I have never had that happen in either of the G1000 172's I fly..

My questions from the blurred pictures are as others have pointed out,
why are you doing 47-50kts?

Why in the engine RPM at exactly 1000, ( when I'm descending it never gets that low even with an idle power setting)?

why is the main amp bus have a negative state and why in the back up yellow ??
Click to expand...

narchee said:
Why is the MFD off? Besides not seeing the MFD on in your photo picture, the tell tale other sign is that the engine parameters are on the PFD.

I've had the AHRS fail if there is excessive vibration but it then resets itself within 20 seconds or so while displaying that message "AHRS ALIGN: Keep wings level" that you are also seeing. Your indicated speed is a little on the low side while you're snapping pictures and otherwise distracted by the G1000 acting up... You need to watch out for that.
Click to expand...

The pictures were taken during the roll-out, and obviously I wasn't the pilot flying.

If you look closely the RPM are at around 700-730, hence the yellow indication.

This is how we fly during instruction flights:

oGTbgGA.jpg


Engine parameters appear on both displays.

I've had the AHRS fail if there is excessive vibration but it then resets itself within 20 seconds or so while displaying that message "AHRS ALIGN: Keep wings level" that you are also seeing.
Click to expand...

Same case.
 
IIRC, unlike the basic block diagram posted above, Cessna's G1000 package has dual AHRS. As such, you should not have seen the indications above unless both AHRS units failed simultaneously, which is highly unlikely. Loss of one AHRS would give you a warning, but you should not have seen the big red X's unless both AHRS units failed. Definitely needs to go to the shop before you launch into the goo, although IIRC, you can fly Day VFR with the AHRS out if you need to fly it to the shop -- see the Kinds of Operations table in Section 2 Limitations of your POH/AFM.
 
Ron Levy said:
IIRC, unlike the basic block diagram posted above, Cessna's G1000 package has dual AHRS. As such, you should not have seen the indications above unless both AHRS units failed simultaneously, which is highly unlikely. Loss of one AHRS would give you a warning, but you should not have seen the big red X's unless both AHRS units failed. Definitely needs to go to the shop before you launch into the goo, although IIRC, you can fly Day VFR with the AHRS out if you need to fly it to the shop -- see the Kinds of Operations table in Section 2 Limitations of your POH/AFM.
Click to expand...

A power loss/surge could cause both to reboot, combo weak battery and low RPM condition.
 
Ron Levy said:
IIRC, unlike the basic block diagram posted above, Cessna's G1000 package has dual AHRS. As such, you should not have seen the indications above unless both AHRS units failed simultaneously, which is highly unlikely. Loss of one AHRS would give you a warning, but you should not have seen the big red X's unless both AHRS units failed. Definitely needs to go to the shop before you launch into the goo, although IIRC, you can fly Day VFR with the AHRS out if you need to fly it to the shop -- see the Kinds of Operations table in Section 2 Limitations of your POH/AFM.
Click to expand...

I'm not so sure about that. I believe at least on the C172 G1000 it's a single AHRS unit.
 
Ron Levy said:
IIRC, unlike the basic block diagram posted above, Cessna's G1000 package has dual AHRS. As such, you should not have seen the indications above unless both AHRS units failed simultaneously, which is highly unlikely. Loss of one AHRS would give you a warning, but you should not have seen the big red X's unless both AHRS units failed. Definitely needs to go to the shop before you launch into the goo, although IIRC, you can fly Day VFR with the AHRS out if you need to fly it to the shop -- see the Kinds of Operations table in Section 2 Limitations of your POH/AFM.
Click to expand...

The G1000 installations in the Cessna 172, 182 and 206 all only have one AHRS and one ADC. That block diagram posted earlier is correct.
 
Bereikua said:
Thank you for all the answers guys.





The pictures were taken during the roll-out, and obviously I wasn't the pilot flying.

If you look closely the RPM are at around 700-730, hence the yellow indication.

This is how we fly during instruction flights:

oGTbgGA.jpg


Engine parameters appear on both displays.



Same case.
Click to expand...

Ah, okay, so you must have pushed the red reversionary mode button now that I see the full image so you could get the PFD display on both sides.

Like I said earlier it is possible for the AHRS to reset itself if it experiences a lot of vibration. I've had the G1000 AHRS reset itself just from bumps while taxiing on Cessna singles. On other installations where you have dual AHRS's it will just switch to the other working one so this doesn't happen as frequently. Luckily, as you experienced, the AHRS is able to reset itself quite easily.
 
narchee said:
Ah, okay, so you must have pushed the red reversionary mode button now that I see the full image so you could get the PFD display on both sides.

Like I said earlier it is possible for the AHRS to reset itself if it experiences a lot of vibration. I've had the G1000 AHRS reset itself just from bumps while taxiing on Cessna singles. On other installations where you have dual AHRS's it will just switch to the other working one so this doesn't happen as frequently. Luckily, as you experienced, the AHRS is able to reset itself quite easily.
Click to expand...

I was amazed that the AHRS for my G-500 performed flawlessly in the beating we were taking holding waiting for the storm on OSH to pass. It never blipped and accurately represented inadvertant aerobatic attitudes. I just wish it had an accelerometer display, that would have been an interesting graph.
 
narchee said:
The G1000 installations in the Cessna 172, 182 and 206 all only have one AHRS and one ADC. That block diagram posted earlier is correct.
Click to expand...
That block diagram is not correct for all G1000's, as the Cirrus has two. I just couldn't remember if the Cessnas had one or two AHRS. I know for sure the Diamonds have one, and I routinely pull the c/b to kill the AHRS during instrument training in a G1000 Diamond because it is a potential failure, and most pilots have trouble flying accurately with the resulting presentation unless they've practiced it. With only a single AHRS, I would do the same for instrument training in a Cessna, too.
 
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