EMB-300 Phenom Yaw Damper Fail Due To Unreliable OR UNAVALIBLE GPS SIGNAL

[Inverted]

The yaw damper should not be affected by this as AHRS would still function with a GPS LOI. I believe this was one of ours. We heard rumblings of an uncommanded Dutch roll and an emergency descent. The 300 still has a ventral rudder as a backup to the single yaw damp.

I'm not completely buying the reason for this story yet. Also, we flew right through it on Thursday on the way to RDU and no aircraft systems were compromised.

 

[TUCKnTRUCK]

The yaw damper should not be affected by this as AHRS would still function with a GPS LOI. I believe this was one of ours. We heard rumblings of an uncommanded Dutch roll and an emergency descent. The 300 still has a ventral rudder as a backup to the single yaw damp.

I'm not completely buying the reason for this story yet. Also, we flew right through it on Thursday on the way to RDU and no aircraft systems were compromised.

It still functions just fine, but it recognizes the loss of input, and that may be what causes the loss of the YD.

You should still have position information from DME/DME. Most FMS's actually uses DME/DME and backs it up with GPS information. To get this failure you would really need to lose both as I understand it.

 

[Inverted]

That should have nothing to do with the yaw damp. And it should especially have nothing to do with the ventral rudder failing as well. Again I am pretty sure this was ours, and this was accompanied by a Dutch roll and an emergency descent because of it.

 

[TUCKnTRUCK]

That should have nothing to do with the yaw damp. And it should especially have nothing to do with the ventral rudder failing as well. Again I am pretty sure this was ours, and this was accompanied by a Dutch roll and an emergency descent because of it.

Yaw damper systems gets attitude information from the AHRS, rate of turn (from HSI).I believe it also gets the speed input from it. If that information is flagged, no YD.

As to the rest, no idea, but, the HSI mag info is reliant on the GPS position otherwise it reverts to a standard compass, which could be off by a fair amount, and kick of the YD when it swings.

 

[mshunter]

Sounds to me like a pretty bad design, maybe to be accompanied soon by an AD.

(At least it should be)

 

[Inverted]

I know, my point is

Yaw damper systems gets attitude information from the AHRS, rate of turn (from HSI).I believe it also gets the speed input from it. If that information is flagged, no YD.

As to the rest, no idea, but, the HSI mag info is reliant on the GPS position otherwise it reverts to a standard compass, which could be off by a fair amount, and kick of the YD when it swings.

Yea but having GPS issues shouldn't really mean anything for AHRS. I know I have flown this airplane without GPS signals and everything worked fine in green needles.

When we did green needle scenarios in the sim, there was no "reverting" of mag info that was displayed. AHRS worked as advertised.

 

[JeppUpdater]

Here's a pic from the other day doing a contract flight in a 100 with complete dual GPS outage and AHRS faults with the YD working fine.

I've spoken with two guys today about it who've lost GPS entirely in 300s and haven't had associated YD or ventral rudder issues. I haven't had the 'pleasure' of a GPS outage in the 300 yet.

By the way it's EMB-505, not EMB-300. That's been driving me nuts.

 

[TUCKnTRUCK]

I know, my point is


Yea but having GPS issues shouldn't really mean anything for AHRS. I know I have flown this airplane without GPS signals and everything worked fine in green needles.

When we did green needle scenarios in the sim, there was no "reverting" of mag info that was displayed. AHRS worked as advertised.

I don't have access to the FSI cam, anymore but-

Anyways, the AHRS uses gps to determine its position for the mag. Field variation. If you loose both GPS and DME/DME you fall into AHRS -No Gps. (Mag north, not true north)

If you lose both GPS and DME position, the magnetic compas will no longer be corrected - setting invalid sensor data. This is all largely academic though, as the systems are all integrated, so invalid inputs to the AHRS is pretty much the same thing as an invalid input to the AFS.

If you happen to be in heading mode, and lose GPS position and DME position ( no indications) then the HDG information to the AFS may drop. If the Mag only info is split between the left and right, or, if it moves more than 6* per second. If it looses the heading input, it would cause a disconnect of the AFS if flying in HDG (and possibly other) modes.

With the YD off, there's a pretty good chance the airplane will Dutch roll. Most pilot attempts to correct Dutch roll lead to PIO, which can be extreme.

In reality it shouldn't happen, but, you know how that goes.

The Prodigy and G2000 were the first to allow DME/DME RMU for area nav, so, the plane will still have mag. Variation location, so, normally you shouldn't see anything happen

 

[Inverted]

I'm not saying they aren't tied in, I'm just saying I've had a total GPS LOI and have still had use of the autopilot, YD, and noticed no directional reversion. NetJets doesn't require an intimate level of knowledge on systems integration like this, but the plane will fly fine, or did fly fine without GPS signals.

 

[dustoff17]

Was the aircraft in this discussion on a reposition/ferry flight or was it loaded with passengers? Anyone....?

 

[Inverted]

I don't know. It's hard to find out info on it right now.

 

[TUCKnTRUCK]

I'm not saying they aren't tied in, I'm just saying I've had a total GPS LOI and have still had use of the autopilot, YD, and noticed no directional reversion. NetJets doesn't require an intimate level of knowledge on systems integration like this, but the plane will fly fine, or did fly fine without GPS signals.

It should keep plugging along just fine without GPS... the 300 (505) has the ability for DME/DME/RMU RNAV, it shouldn't need the GPS - but, if all the holes happen to line up, there is a possibility that loosing both GPS signals may cause issues.

 

[PhilosopherPilot]

Welcome to Embraer, where to reset a printer I have to turn off hydraulic pumps, and pull a circuit breaker to disable MAU3.

 

[averettpilot]

Welcome to Embraer, where to reset a printer I have to turn off hydraulic pumps, and pull a circuit breaker to disable MAU3.

Every Mechanical Breakdown Requires An Electrical Reset

 

[PhilosopherPilot]

Every Mechanical Breakdown Requires An Electrical Reset

Coming from CRJ, I was used to "reset jet" procedures. But Embraer takes it to a whole other level!

 

[averettpilot]

Bringing this back to life, we had a total loss of GPS which led to AHRS1/2 faults. Still had YD and AP, although this was in a 100 so not directly applicable to the scenario described for the 300.

The peculiar thing was we also lost DME. This was all due to gps jamming (at least the LOI on GPS). Embrear seemed to think the loss of DME was also due to the GPS jamming since they are on similar frequencies.

Was interesting to go from no big deal we'll just go green needles and switch the arrival, to shoot we can't identify any of the fixes without DME. "Hey ATC, vectors please."

 

[Fly_Unity]

Two Days ago in the SLC area, in a King Air at FL230, We lost GPS1, then a few minutes later we lost GPS2, then we lost all VORs, and then last of all, lost ownship position in the iPad. Inquired ATC and their response was "Did Center not tell you you was going to lose GPS? Sorry, the Military is jamming things up". We then got vectors for the next hour.

My question is, why did we lose VOR's too? ATC said that we should NOT have lost it. We still had DME.

 

[averettpilot]

Two Days ago in the SLC area, in a King Air at FL230, We lost GPS1, then a few minutes later we lost GPS2, then we lost all VORs, and then last of all, lost ownship position in the iPad. Inquired ATC and their response was "Did Center not tell you you was going to lose GPS? Sorry, the Military is jamming things up". We then got vectors for the next hour.

My question is, why did we lose VOR's too? ATC said that we should NOT have lost it. We still had DME.

Yup. This on arrival to SLC, just before BCE. Switched us from the QWENN4 to the JAMMN4 (wonder how they picked that name?) We knew about the jamming but did not expect losing DME. We still had VORs just couldn't identify any of the fixes on the arrival other than the VORs.

 

[mshunter]

Two Days ago in the SLC area, in a King Air at FL230, We lost GPS1, then a few minutes later we lost GPS2, then we lost all VORs, and then last of all, lost ownship position in the iPad. Inquired ATC and their response was "Did Center not tell you you was going to lose GPS? Sorry, the Military is jamming things up". We then got vectors for the next hour.

My question is, why did we lose VOR's too? ATC said that we should NOT have lost it. We still had DME.

My question is, what is the military so worried about? Why are they testing all of their jamming capabilities?

 

[JeppUpdater]

Why are they testing all of their jamming capabilities over huge swathes of civilian airspace?

FIFY.

Similar to my comments on TCAS jamming...if you want to go test jamming capabilities, that's fine. Do it in a controlled MOA or restricted area without affecting thousands of civilian flights. As we can see in this topic, this isn't just an interruption of convenience, it could lead to some serious issues in our GPS-based industry.

But as always it's "we need to do whatever we want wherever we want because zomg terrorism."