What does prop rpm have to do with AHRS?

[pelmet]

Must be vibration somehow affecting it. Isn't AHRS normally laser gyros?

The Keewatin Air Beechcraft B200, C-FRMV operating as flight KEW202 had departed CYWG,
Winnipeg on a positioning flight to CYRT, Rankin Inlet. While en-route the crew experienced a
complete failure of the Altitude and Heading Reference System (AHRS). The crew declared an
emergency and returned to Winnipeg using standby instruments. The crew reduced the propeller
RPM to 1700 for the descent into Winnipeg. The AHRS came back on-line within one minute. The
subsequent landing was uneventful. Garmin G1000 Service Alert 1504 Rev A, concerns B200
aircraft fitted with 3-blade propellers and warns against engine operation in the 1920 to 1960
propeller RPM range. The Service Alert resolution states that the issue will be resolved with a
future GRS 7800 hardware change.

[photofly]

G1000 uses MEMS - one thousandth of the price.

[AirFrame]

Apparently that RPM range hits some resonant frequency that makes the G1000 go TU.

I have a mems-based PFD in my RV, I haven't noticed any issues due to certain vibration frequencies but I don't operate at 2000rpm much. Taxiing at 800rpm, run-up at 1800, then takeoff and flying where i'm well over 2000, are the only points where it might dwell. I wonder if Garmin knew about the 1950rpm point and figured it wouldn't match anyone's operating range?

[Illya Kuryakin]

This was an emergency? Really?
Illya

[Cat Driver]

The crew reduced the propeller
RPM to 1700 for the descent into Winnipeg. The AHRS came back on-line within one minute. The
subsequent landing was uneventful.

Wow, they sure were lucky I can not imagine what would have happened if they had to complete the flight with only standby instruments....chilling thought ...horrifying.

[Illya Kuryakin]

The crew reduced the propeller
RPM to 1700 for the descent into Winnipeg. The AHRS came back on-line within one minute. The
subsequent landing was uneventful.

Wow, they sure were lucky I can not imagine what would have happened if they had to complete the flight with only standby instruments....chilling thought ...horrifying.

MAYDAY MAYDAY MAYDAY!!!! Send lawyers, guns and money! The shit has hit the fan! We're reverting to round dials!!! Tell my mom I love her.
Illya

[switchflicker]

It's interesting that the two biggest ice-halos on the forum both pipe up with the usual drivel towards what was an interesting anomaly in the modern day navigation systems

Keep it up boyz. you never cease to amaze us

Sw

[Illya Kuryakin]

It's interesting that the two biggest ice-halos on the forum both pipe up with the usual drivel towards what was an interesting anomaly in the modern day navigation systems

Keep it up boyz. you never cease to amaze us

Sw

Guess you missed the point. Educate us on how this could be called an emergency. Ooops, my VSI just packed in and, I broke a nail....MAYDAY!
Illya

[shimmydampner]

I don't know what constitutes standby instruments in that aircraft. Maybe you do, Doc. To me it means a second attitude indicator, altimeter and maybe an RMI. I also don't know what the weather was that day. Maybe you do, Doc. It isn't difficult to imagine a scenario where the weather is crappy enough and the instrumentation sparse enough that a complete AHRS failure would make for a bad day at the office. Who says that the only time it's appropriate to declare an emergency is during situations requiring a heroic effort to get the plane back on the ground in one piece? Sure, in this scenario, a pilot should be able to navigate to a successful landing, but just because there is backup instrumentation doesn't detract from the fact that complete failure of the main system is a serious abnormal situation. That's like saying that an engine failure is not an emergency because there's still another one turning and every pilot should be able to fly successfully on just one. I mean, we practice it all the time, should be a no brainer.
At the end of the day, I guess I just don't understand why it's worth your energy to go out of your way to shit on a fellow aviator who dealt with a serious abnormal situation effectively and safely. I doubt Winnipeg ATC or any emergency services were inconvenienced or upset about it.

[Cat Driver]

Does the autopilot fail when there is a AHRS failure on that airplane?

[fish4life]

I'd imagine in most aircraft if you are down the the peanut gauges you won't have any auto pilot.

[Cat Driver]

Why would they design an airplane that uses two engines, two pilots but only one attitude sensing method?

[xsbank]

As this incident would seem to be self-inflicted, rather than trash them for declaring an emergency, I would trash them for not knowing their Limitations. Having never been typed in a BE20, I would hazard a guess that there is a QRH response to this issue that they also didn't follow. I reached that conclusion because it repaired itself.

Training? Understanding the system? We had AHRS in the Challenger 300 and compared to its bigger brothers, I thought it was Mickey Mouse.

There are some questions to be asked for sure, but Doc's way is more fun! Doc might be crusty but he's usually right and he's certainly not reticent to point a (middle) finger!

[oldncold]

Once again xbank. Quarterbacking from the sofa. Is astounding. Many 703 operators (but. Not all. Employ 2 pilots not only for a safety or customer requirement but for an economic one. Which is having a co pilot or co captain. Means 2 things. (a).14 hour duty day ifr and (b) no need for a functional autopilot. - I did not read to see if the incident was at night. But if you have a ahars failure. In a be20. The inverter might have failed. Causing the thing to quit. Until switched to the other one. Standard procedure on many olé steam drive. Systems if that happens on the first 400 ft in daytime or 1000 ft at night is transfer control to the non flying pilot and change inverters. as mentioned the prop vibration.(that's never happened to me but understand how it could). Less blah blah blah your so successful and important. More constructive opinions. X.

[oldncold]

Good show to that crew. Especially if it was at night and on the backside of a long duty day. There will always be nasty mouthed critics of what should be done. but staying true to your training /sop's and the inner voice based on operational conditions aircraft status and exp will give you the best opportunity to really reach olé fart remember when status. Fate is the hunter. Good job again

[xsbank]

I think I've been insulted. I am pleased that you think I'm important, but I suppose it's meaningless if you are in your cups. Tomorrow, I'll still stand by my opinion but you'll have a headache. Greasy bacon and eggs will help.

Was that you in the Beech, Old? Inverter failure caused a Mayday? Even I know they've got two.

For the record, I know how the the two-pilot thing works, I had lots to do with that.

I just read your last post, I have officially reached "olé" fart status. Which reminds me, I have to take the dog for a dump.

[oldncold]

Well x. Being over 50 my greasey food intake is restricted to once a week so that I can continue to enjoy this crazy av biz until doc age at least I'm only half way there. Next in keeping with a healthy ( oh crap). Not 30 anymore the only "cups" I wish to see are female and respectfully at that. So yes you have been insulted in a good natured way.

Ps hope your dog. Didn't miss and poop on your shoes that you get on the challenger 300 with. That may cause a mayday with your clients. That crew did a good job. Less theater more substance x

[teacher]

I gotta say, you guys are morons. First, other pilots are not smart or good enough to take the safe route out and go around, now a complete loss of primary flight instruments in IMC and this is just routine? Seriously guys you embarrass yourselves. Any other incidents today that you can make fun of? Maybe belittle some more pilots? I got it!!! Tell us how amazing your stick and rudder skills are and how you can do no wrong!!!!

I've had a complete AHRS failure and it was NOT a fun approach. Flying along IMC with blank EFIS screens and nothing but a VOR/ILS and peanut gyro isn't fun. Maybe they suspected something more sinister was going in? Maybe they didn't wanna be given a hold, vectors or delays while hand flying off standby instruments wondering which dial was gonna fail next?

[Illya Kuryakin]

I gotta say, you guys are morons. First, other pilots are not smart or good enough to take the safe route out and go around, now a complete loss of primary flight instruments in IMC and this is just routine? Seriously guys you embarrass yourselves. Any other incidents today that you can make fun of? Maybe belittle some more pilots? I got it!!! Tell us how amazing your stick and rudder skills are and how you can do no wrong!!!!

I've had a complete AHRS failure and it was NOT a fun approach. Flying along IMC with blank EFIS screens and nothing but a VOR/ILS and peanut gyro isn't fun. Maybe they suspected something more sinister was going in? Maybe they didn't wanna be given a hold, vectors or delays while hand flying off standby instruments wondering which dial was gonna fail next?

What do you want me to say? Gee Teacher, I'm so sorry I didn't recognize the impending doom this crew faced. News flash for you...we are very far from being "morons". So sorry. I'm so very happy nobody died, what with the approaching minimums in solid IMC (which, BTW, would not have been an issue because the prop RPM might have been in the proper range as per the pilot's notes on the system operating procedures?) but the initial post (read it....you're the teacher) let us to believe it was an enroute problem. But, call us "morons" if it makes you feel better. Cheers.
Illya

[xsbank]

Teacher, pull out the pickle. You can call me all the names you want but this is a huge red flag and should be looked at more closely.

Is there a procedure in the QRH a about an AHRS a failure? Does it say "Declare and land at the nearest suitable airport?"

Could either pilot pass an oral exam on the Limitations of their aircraft?

I'm happy they declared the emergency and landed safely, but aren't they telegraphing to the world about how ignorant they are? You do realize that anyone over, say, 40, only had had a steam-powered gyro and ILS/VOR to fly with? How do you think we all survived flying all over the planet with only that meagre stuff? Is your training so crap that an electronic failure that only changes your guidance information, puts the aircraft at such risk in your hands that you have to declare?

I think you guys should give your heads a shake and get back into the books. You guys who are praising these guys sound like candidates for an Air Indonesia/Turkish Airlines etc etc loss of control.

Maybe once in a while you should take some cardboard with you, shut off the autopilot and try flying partial panel. You do know what that means?

If you want to be called "Professionals" you should all start acting like one.

I'm done with this thread.

[Illya Kuryakin]

Just one comment, them I'm gone from this thread as well
Teacher, I guarantee I've had more inflight problems than you've dreamed about.
When something goes "south" on me (and it has)I run a checklist (if needed) before I have a litter of kittens. If this RPM thing was (it should have been) on the list.....well?
One doesn't really need to "know" every system on board, but they should be able to "dig" it up.
Illya

[The De-Icer]

Ok so clearly there's a lot of misunderstanding of the G1000/ahrs around here.

First of all, with the G1000 installation, inverters are removed as they are unnecessary.

Second of all, the stand by instruments in these installations from what I have gathered, are a standby Attitude indicator, altimeter, and airspeed indicator.

From what I've been told the crew had a DUAL ahrs failure and it was at night and in cloud and no navigation equipment remaining except for a compass. Obviously no autopilot since the autopilot needs a reference and with no primary adi's, hsi's, it's out for lunch.

So tell me this boys, if you have no ability to fly an ifr approach, navigate without vectors, fly a hold if needed, is it an emergency?

Does declaring an emergency cost money? Does potentially being more safe than necessary ever harm anyone?

If the crew hadn't declared, got lost, lost more equipment, and had more issues down the road would you boys jump on their asses about not declaring an emergency earlier?

Illya don't forget, if you think you know everything then you need to find another job because the truth is, you don't.

love & tickles

[teacher]

Ok so clearly there's a lot of misunderstanding of the G1000/ahrs around here.

First of all, with the G1000 installation, inverters are removed as they are unnecessary.

Second of all, the stand by instruments in these installations from what I have gathered, are a standby Attitude indicator, altimeter, and airspeed indicator.

From what I've been told the crew had a DUAL ahrs failure and it was at night and in cloud and no navigation equipment remaining except for a compass. Obviously no autopilot since the autopilot needs a reference and with no primary adi's, hsi's, it's out for lunch.

So tell me this boys, if you have no ability to fly an ifr approach, navigate without vectors, fly a hold if needed, is it an emergency?

Does declaring an emergency cost money? Does potentially being more safe than necessary ever harm anyone?

If the crew hadn't declared, got lost, lost more equipment, and had more issues down the road would you boys jump on their asses about not declaring an emergency earlier?

Illya don't forget, if you think you know everything then you need to find another job because the truth is, you don't.

love & tickles

Exactly. Degrading other pilots especially when they've had an inflight issue is one of the top forms of unprofessional behaviour. Belittling another pilot when they've made an error that may or may not have pranged an airplane also fits in the above statement. It may have been rude and unprofessional calling you guys morons but kicking a fellow pilot when they're down or after the fact of them making a decision when you weren't there is kinda moron-ish. I'll tell you. When we lost all our screens and had nothing but a peanut gyro it was no picnic and being at night in IMC would have raised our pucker factor.

Someone once told me "there's pilots that have and those that will" when it comes to errors and incidents. If you think you're above making an error than you're either the best pilot we've ever seen or not entirely truthful.

[Meatservo]

I was just thinking about this event and trying to relate it to a few of the planes I fly at work. One of them has all "steam" gauges, and it's pretty difficult to imagine anything other than a complete and utter electrical failure taking out enough of them to make it necessary to continue flying on just the "peanut" horizon. By the time it's down to that instrument being the only one that works, the same electrical failure that knocked out the main horizons would almost certainly have robbed us of any radio-navigation ability. I imagine the peanut in that plane is pretty much only there to keep you right-side-up until you can get down under the clouds and hope you can figure out where you are.

The other one is designed so that if you're down to the mechanical gauges, there's also one ILS receiver and an RMI still working.

BUT, I'm thinking, if I was down to that power level, I'd probably go back home instead of finishing the trip, because, you know, it's probably illegal or something to land at some place away from base and then plan to come home again after dropping off the passengers. Maybe the primary attitude instruments are on the MEL or something. I'm thinking they probably aren't deferrable. Also if I was in IMC, maybe I would declare something, maybe not an emergency, but whatever- so you can get some kind of special handling... I don't know how much fun it would be to bumble my way through some kind of STAR or other procedure like a hold, using just the RMI, maybe I would appreciate vectors straight onto the ILS instead. Maybe I would indicate in some way to ATC that this wasn't just a frivolous request but instead was on account of some equipment failure or degraded navigational performance.

What bugs me more than whether or not I feel like reverting to the peanut gauges in a glass cockpit constitutes an emergency or not, is like Cat Driver says, this plane seems to only have one source of attitude information going to the screens. That doesn't seem right to me.

[Cat Driver]

like Cat Driver says, this plane seems to only have one source of attitude information going to the screens. That doesn't seem right to me.

I was wondering if an airplane with a modern glass cockpit would be designed so you would lose the autopilot when the AHRS failed...

....leaving you with having to hand fly the thing while you re organized your options?

Someone here should know the answer.