AHRS Failure

PhilosopherPilot · March 19th, 2006, 23:19

Hi All,

I had my most interesting round trip so far the other day. I won't go into details on here, but we had an AHRS 1 failure on takeoff yesterday on the way to ATL from IND. It was the Captain's leg, so I was a little surprised to take the controls on climbout. We were never in any danger, and were in VMC.

The AHRS is the attitude heading reference system (for those that don't know), so the captain lost his attitude, airspeed, altitude, and heading indicators... Also, we lost Yaw Damper 1 and Stab Trim 1. The system would reset, then trip off again after a few seconds. Unfortunately, this meant that the autopilot would engage on my side, but even with the Captain side on my AHRS, the autopilot tripped off each time.

So that means that a brand spanking new FO like me got to hand fly back to ATL. The Captain said it was part of "paying my dues"...lol We did actually remember to not go into RVSM airspace.

Anyway, it was an interesting experience. I enjoyed it, even if it did zap my energy.

G

pscraig · March 20th, 2006, 03:16

Nice! That's happened to me once, but in the ERJ the autopilot will stay on if the FD is coupled to the side with the good AHRS.

So how does she handle?

casey · March 20th, 2006, 03:22

Quote:

Originally Posted by PhilosopherPilot

The AHRS is the attitude heading reference system (for those that don't know), so the captain lost his attitude, airspeed, altitude, and heading indicators...

We did actually remember to not go into RVSM airspace.

not to nitpick, but your airspeed and altitude are coming from your ADC (airspeed, altitude, vertical speed), not AHRS (heading, pitch, bank). You can also ask to go up into rvsm while "negative rvsm". If the controller can provide you the extra spacing he needs, he can approve you up there.

nice handling of the situation

PhilosopherPilot · March 20th, 2006, 10:32

Quote:

Originally Posted by casey

not to nitpick, but your airspeed and altitude are coming from your ADC (airspeed, altitude, vertical speed), not AHRS (heading, pitch, bank). You can also ask to go up into rvsm while "negative rvsm". If the controller can provide you the extra spacing he needs, he can approve you up there.

nice handling of the situation

Yeah, I thought of that after I posted, but it seemed to me that those indications went blank as well. It wasn't on my side though, so I can't remember. As far as RVSM goes, captain said tell the controller unable RVSM, so I did.

As far as the AP is concerned, I thought it would stay on if coupled to my side too, but for some reason it wouldn't. I think it was because every time the AHRS blipped, the yaw damper would trip off, which killed the AP. Any ideas??? We even left the YD1 off to see if it would still trip the AP off, and it did...

G

BobDDuck · March 20th, 2006, 10:42

Not sure of why, but on the CRJ the YD1 is linked to the ADC on the left side. I guess the AHRS dieing was too much for the ADC1 to handle and it was tripping the YD1 (which kicks the AP off). Got to love the system overlap on the CRJ.

Captain_Bob · March 20th, 2006, 12:39

I feel for you... Fresh out of IOE I get a plane with the Autopilot MEL'd and we did a EWR-DCA turn! It was like a friggin' PC with an instructor form he!!.

"Jetlink 1234, Turn 20 right for vectors into DCA and decend and maintain fl230, slow to 270 knots."
"Jetlink 1234, heading 180, descend fl170, slow to 250 knots, altimeter 29.96, traffic 10 o'clock 1000' ft below, heading 090, an MD80."
"Jetlink 1234, turn 30 degrees left for vectors ILS RWY XX, slow to 210, upon slowing to 210 decend and maintain 8000, traffic a CRJ 11 o'clock and 8 miles, advise traffic in sight."
ETC...

LOL! It seemed every call was like that... Never once just a simple "decend and maintain" or "slow to" call. Fun stuff...

Bob

EDUC8-or · March 20th, 2006, 13:23

I've seen the avionics/AP do some weird stuff on the CRJ. It's like the Windows 2000 of systems. Good job on the return!

My sim partner during 700 differences was a captain and he lost his PFD below 80 knots. I didn't see it (now I know to look at both PFD's when I'm PNF) he kept going and gave me the controls at V1. Now I'm not so lax when I'm the PNF.

NJA_Capt · March 20th, 2006, 14:30

Quote:

Originally Posted by PhilosopherPilot

As far as the AP is concerned, I thought it would stay on if coupled to my side too, but for some reason it wouldn't.

On the Primus 2000 system in our aircraft, autopilot operations are prohibited with an inop AHRS/IRS. It is an aircraft limitation.

Quote:

Originally Posted by EDUC8-or

My sim partner ...captain ...lost his PFD below 80 knots. ...he kept going and gave me the controls at V1.

I hope that display of how not to do something was in the sim! I further hope the sim instructor had some...creative...suggestions for future failures.

PhilosopherPilot · March 20th, 2006, 14:40

Quote:

Originally Posted by BobDDuck

Not sure of why, but on the CRJ the YD1 is linked to the ADC on the left side. I guess the AHRS dieing was too much for the ADC1 to handle and it was tripping the YD1 (which kicks the AP off). Got to love the system overlap on the CRJ.

That might explain why the airspeed and alt info was going away as well. It is possible that the problem was more than the AHRS though. We didn't talk to Mx afterwards to follow up with the problem. I would like to know what was going on, just for future reference.

G

PhilosopherPilot · March 20th, 2006, 14:43

Quote:

Originally Posted by Captain_Bob

I feel for you... Fresh out of IOE I get a plane with the Autopilot MEL'd and we did a EWR-DCA turn! It was like a friggin' PC with an instructor form he!!.

"Jetlink 1234, Turn 20 right for vectors into DCA and decend and maintain fl230, slow to 270 knots."
"Jetlink 1234, heading 180, descend fl170, slow to 250 knots, altimeter 29.96, traffic 10 o'clock 1000' ft below, heading 090, an MD80."
"Jetlink 1234, turn 30 degrees left for vectors ILS RWY XX, slow to 210, upon slowing to 210 decend and maintain 8000, traffic a CRJ 11 o'clock and 8 miles, advise traffic in sight."
ETC...

LOL! It seemed every call was like that... Never once just a simple "decend and maintain" or "slow to" call. Fun stuff...

Bob

Same thing here. We were coming into ATL, right about the time that 27L lost lighting, and all a/c were landing on 26R. We got more vectors and speed changes than I've ever had coming to ATL...

G

EDUC8-or · March 20th, 2006, 14:52

Quote:

Originally Posted by NJA_Capt

I hope that display of how not to do something was in the sim! I further hope the sim instructor had some...creative...suggestions for future failures.

The captain was buying that night. He got chewed OUT!

FlyChicaga · March 20th, 2006, 15:01

Threads like this remind me why I hand fly so much. On short legs I'll sometimes hand fly the entire leg, except to reach behind and pull out my charts for the arrival airport. I've had so many guys ask, "You're not on autopilot yet? Geez, you're motivated!" Just have to watch the autopilot fail once after months of its use to see the need to keep your scan and handflying skills sharp!

I'm with NJA_Capt, surprised with the failure of the CA's PFT in your post EDUC-8r that he (the CA) didn't call for an abort.

OldTownPilot · March 20th, 2006, 21:19

My dad does mostly Europe flying, so the A/P goes on for the crossings. However on the SNN-DUB legs most guys hand fly it for the 30 minute flight or so.

A crew at his airline had an autopilot not engage coming out of FCO, and they hand flew it the entire way back to the States. Now that is a long way without an A/P. At least it was a 3 crew flight with a relief pilot so they could take a break.

DE727UPS · March 21st, 2006, 00:09

"A crew at his airline had an autopilot not engage coming out of FCO, and they hand flew it the entire way back to the States."

Man....I think I'd start asking for volunteers from the back of the plane to come up and help me out.

Doug Taylor · March 21st, 2006, 00:12

Good grief. SAN-SLC without an autopilot whipped my butt. I'm surprised they dispatched with an inop autopilot.

Alchemy · March 21st, 2006, 04:15

P.Pilot, good job on handling the situation, I'm sure it was good experience. That is a long flight for hand flying.

I'm still not sure what's worse....MEL'd Autopilot or MEL'd FMS. With all the functionaitlity we get out of the FMS, (Weight and Balance, Performance Initialization, ACARS in range calls, not to mention RNAV), I'd rather give up the autopilot if the flight is shorter than 2 hours enroute. We did CLE-IAD a few months ago with no FMS. It was interesting, especially since ATC gave us some weird airway re-routes, but manageable.

I've handflown the EMB up to FL370 a few times for kicks....nothing too demanding about it, just takes concentration like any other phase of flight, although it gets a little pitch-sensitive in the 30's. I'm almost surprised you guys were able to stay out of RVSM on IND-ATL without taking a fuel hit, but I guess it's only 400 NM or so.

Of course we have some guys around here that do this kind of masochistic stuff for fun, they call themselves Beech Drivers. You know you're flying with an Ex Beech driver when he's always backing you up in cruise with Green Needles on your legs, and on his legs disengages the autopilot and turns the flight guidance off below 10.

Doug Taylor · March 21st, 2006, 12:03

Green needles?

Bandit_Driver · March 21st, 2006, 12:06

Quote:

Originally Posted by PhilosopherPilot

Hi All,

I had my most interesting round trip so far the other day. I won't go into details on here, but we had an AHRS 1 failure on takeoff yesterday on the way to ATL from IND.

Good job on handling the situation.

I had similar situation in the Saab but we had to abort the takeoff. Both AHRS rolled inverted due a severe vibration caused by a nosewheel throwing a weight off prior to V1.

EDUC8-or · March 21st, 2006, 12:14

Quote:

Originally Posted by Doug Taylor

Green needles?

Can't speak for the ERJ, but we're (CRJ) in white needles when FMS is the nav source. When we're on NAV1 or 2 it goes green needles.

Doug Taylor · March 21st, 2006, 12:15

Jason · March 21st, 2006, 13:47

Try and keep up with the technology Doug!!

Regarding an Atlantic Crossing with an inop autopilot - holy crap!! It's a long trip back at FL280!

Jason

OldTownPilot · March 21st, 2006, 14:01

As far as the FCO deal, Dad flew with the CA that did it. The auto pilot would not engage after take off, so it was "dispached with a good A/P". Something else endend up being broken that would not allow it to engage. He said they would have had to fly to Ireland or so to be under landing weight, then what? Try to get it fixed there...? The fuel would have been close to make it back at 280 so they flew the crossing, and checked the fuel as they went. Careful co-ordinaton with dispatch was the key to getting it done. Each pilot took 2 shorter breaks than 1 long break, and he said it was easier than they expected.

Heck BGR-PWM is long enough (100+mi) with non A/P in a 150, say nothing of 10 or so hours going across the big drink.

BobDDuck · March 21st, 2006, 22:37

Green Needles Suck! I really need to back tshirt for that. Honestly, I would much rather have the autopilot out then loose the FMS. We mostly fly shorter legs (<2 hours) so it wouldn't be that bad. In cruise it is possible to get the aircraft trimmed out pretty well so it doesn't require to many control inputs. The autopilot (on the CRJ anyways) doesn't touch the trim so very often in cruise it is out of trim and the yoke is always moving.

No autopilot EWR-DCA is pretty busy I would bet. I just can believe you got up to 230 on that flight. PHL-LGA is similar distance and we stay at 9000 the whole way.

Mr_Creepy · March 22nd, 2006, 04:35

I went green needles from RDU to BOS once. That was a nightmare.

Doug Taylor · March 22nd, 2006, 10:12

Quote:

Originally Posted by Mr_Creepy

I went green needles from RDU to BOS once. That was a nightmare.

There's a pill for that!

March 19th, 2006, 23:19	#1
PhilosopherPilot Senior Member Join Date: Jul 2003 Location: Providence, RI Posts: 454	AHRS Failure Hi All, I had my most interesting round trip so far the other day. I won't go into details on here, but we had an AHRS 1 failure on takeoff yesterday on the way to ATL from IND. It was the Captain's leg, so I was a little surprised to take the controls on climbout. We were never in any danger, and were in VMC. The AHRS is the attitude heading reference system (for those that don't know), so the captain lost his attitude, airspeed, altitude, and heading indicators... Also, we lost Yaw Damper 1 and Stab Trim 1. The system would reset, then trip off again after a few seconds. Unfortunately, this meant that the autopilot would engage on my side, but even with the Captain side on my AHRS, the autopilot tripped off each time. So that means that a brand spanking new FO like me got to hand fly back to ATL. The Captain said it was part of "paying my dues"...lol We did actually remember to not go into RVSM airspace. Anyway, it was an interesting experience. I enjoyed it, even if it did zap my energy. G __________________ "I would never die for my beliefs because I might be wrong." Russell

March 20th, 2006, 10:42	#5
BobDDuck Old Skool Join Date: Sep 2003 Location: Left Seat Posts: 5,482	Not sure of why, but on the CRJ the YD1 is linked to the ADC on the left side. I guess the AHRS dieing was too much for the ADC1 to handle and it was tripping the YD1 (which kicks the AP off). Got to love the system overlap on the CRJ. __________________ TBJC08 The Gear Monkey The Gear Monkey Store

March 20th, 2006, 12:39	#6
Captain_Bob Old Skool Join Date: Apr 2003 Location: DFW, based in ONT, wishing I was in Maine Posts: 3,861	I feel for you... Fresh out of IOE I get a plane with the Autopilot MEL'd and we did a EWR-DCA turn! It was like a friggin' PC with an instructor form he!!. "Jetlink 1234, Turn 20 right for vectors into DCA and decend and maintain fl230, slow to 270 knots." "Jetlink 1234, heading 180, descend fl170, slow to 250 knots, altimeter 29.96, traffic 10 o'clock 1000' ft below, heading 090, an MD80." "Jetlink 1234, turn 30 degrees left for vectors ILS RWY XX, slow to 210, upon slowing to 210 decend and maintain 8000, traffic a CRJ 11 o'clock and 8 miles, advise traffic in sight." ETC... LOL! It seemed every call was like that... Never once just a simple "decend and maintain" or "slow to" call. Fun stuff... Bob __________________ My head is in the clouds and my heart is still in Maine... but my devotion and love belong to my wife and children. Pics!

March 20th, 2006, 15:01	#12
FlyChicaga Old Skool Join Date: Dec 2001 Location: Chicago, IL Posts: 4,783	Threads like this remind me why I hand fly so much. On short legs I'll sometimes hand fly the entire leg, except to reach behind and pull out my charts for the arrival airport. I've had so many guys ask, "You're not on autopilot yet? Geez, you're motivated!" Just have to watch the autopilot fail once after months of its use to see the need to keep your scan and handflying skills sharp! I'm with NJA_Capt, surprised with the failure of the CA's PFT in your post EDUC-8r that he (the CA) didn't call for an abort. __________________ "We thought we had the answers, it was the questions we had wrong." - Bono, U2

March 20th, 2006, 21:19	#13
OldTownPilot Old Skool Join Date: May 2005 Location: BGR (Bangor, ME) Posts: 2,898 Blog Entries: 4	My dad does mostly Europe flying, so the A/P goes on for the crossings. However on the SNN-DUB legs most guys hand fly it for the 30 minute flight or so. A crew at his airline had an autopilot not engage coming out of FCO, and they hand flew it the entire way back to the States. Now that is a long way without an A/P. At least it was a 3 crew flight with a relief pilot so they could take a break. __________________ As a wise man said, sumb!tch flew in, sumb!tch'll fly out. Ski Hard. Party Harder.

March 20th, 2006, 03:16	#2
pscraig Senior Member Join Date: Jul 2001 Location: Houston, TX Posts: 1,021	Nice! That's happened to me once, but in the ERJ the autopilot will stay on if the FD is coupled to the side with the good AHRS. So how does she handle?

March 20th, 2006, 13:23	#7
EDUC8-or Old Skool Join Date: Mar 2001 Location: NC Posts: 2,177	I've seen the avionics/AP do some weird stuff on the CRJ. It's like the Windows 2000 of systems. Good job on the return! My sim partner during 700 differences was a captain and he lost his PFD below 80 knots. I didn't see it (now I know to look at both PFD's when I'm PNF) he kept going and gave me the controls at V1. Now I'm not so lax when I'm the PNF.

March 21st, 2006, 00:09	#14
DE727UPS Old Skool Join Date: Nov 2000 Location: Spokane, WA Posts: 6,514	"A crew at his airline had an autopilot not engage coming out of FCO, and they hand flew it the entire way back to the States." Man....I think I'd start asking for volunteers from the back of the plane to come up and help me out.

March 21st, 2006, 00:12	#15
Doug Taylor Agent Smith Join Date: Dec 1969 Location: KSDL Posts: 40,240 Blog Entries: 1	Good grief. SAN-SLC without an autopilot whipped my butt. I'm surprised they dispatched with an inop autopilot. __________________ Doug Taylor http://76school.flyblog.com (old!) http://30west.flyblog.com (updated 11/28)

March 21st, 2006, 04:15	#16
Alchemy Old Skool Join Date: Aug 2001 Location: Austin, TX, USA Posts: 1,748	P.Pilot, good job on handling the situation, I'm sure it was good experience. That is a long flight for hand flying. I'm still not sure what's worse....MEL'd Autopilot or MEL'd FMS. With all the functionaitlity we get out of the FMS, (Weight and Balance, Performance Initialization, ACARS in range calls, not to mention RNAV), I'd rather give up the autopilot if the flight is shorter than 2 hours enroute. We did CLE-IAD a few months ago with no FMS. It was interesting, especially since ATC gave us some weird airway re-routes, but manageable. I've handflown the EMB up to FL370 a few times for kicks....nothing too demanding about it, just takes concentration like any other phase of flight, although it gets a little pitch-sensitive in the 30's. I'm almost surprised you guys were able to stay out of RVSM on IND-ATL without taking a fuel hit, but I guess it's only 400 NM or so. Of course we have some guys around here that do this kind of masochistic stuff for fun, they call themselves Beech Drivers. You know you're flying with an Ex Beech driver when he's always backing you up in cruise with Green Needles on your legs, and on his legs disengages the autopilot and turns the flight guidance off below 10.

March 21st, 2006, 12:03	#17
Doug Taylor Agent Smith Join Date: Dec 1969 Location: KSDL Posts: 40,240 Blog Entries: 1	Green needles? __________________ Doug Taylor http://76school.flyblog.com (old!) http://30west.flyblog.com (updated 11/28)

March 21st, 2006, 12:15	#20
Doug Taylor Agent Smith Join Date: Dec 1969 Location: KSDL Posts: 40,240 Blog Entries: 1	Ahh! __________________ Doug Taylor http://76school.flyblog.com (old!) http://30west.flyblog.com (updated 11/28)

March 21st, 2006, 13:47	#21
Jason Senior Member Join Date: Sep 2000 Location: Cincinnati, OH Posts: 977	Try and keep up with the technology Doug!! Regarding an Atlantic Crossing with an inop autopilot - holy crap!! It's a long trip back at FL280! Jason __________________ ...till we meet again on the high seas...ARRRRGGGGHHHHH

March 21st, 2006, 14:01	#22
OldTownPilot Old Skool Join Date: May 2005 Location: BGR (Bangor, ME) Posts: 2,898 Blog Entries: 4	As far as the FCO deal, Dad flew with the CA that did it. The auto pilot would not engage after take off, so it was "dispached with a good A/P". Something else endend up being broken that would not allow it to engage. He said they would have had to fly to Ireland or so to be under landing weight, then what? Try to get it fixed there...? The fuel would have been close to make it back at 280 so they flew the crossing, and checked the fuel as they went. Careful co-ordinaton with dispatch was the key to getting it done. Each pilot took 2 shorter breaks than 1 long break, and he said it was easier than they expected. Heck BGR-PWM is long enough (100+mi) with non A/P in a 150, say nothing of 10 or so hours going across the big drink. __________________ As a wise man said, sumb!tch flew in, sumb!tch'll fly out. Ski Hard. Party Harder.

March 21st, 2006, 22:37	#23
BobDDuck Old Skool Join Date: Sep 2003 Location: Left Seat Posts: 5,482	Green Needles Suck! I really need to back tshirt for that. Honestly, I would much rather have the autopilot out then loose the FMS. We mostly fly shorter legs (<2 hours) so it wouldn't be that bad. In cruise it is possible to get the aircraft trimmed out pretty well so it doesn't require to many control inputs. The autopilot (on the CRJ anyways) doesn't touch the trim so very often in cruise it is out of trim and the yoke is always moving. No autopilot EWR-DCA is pretty busy I would bet. I just can believe you got up to 230 on that flight. PHL-LGA is similar distance and we stay at 9000 the whole way. __________________ TBJC08 The Gear Monkey The Gear Monkey Store

March 22nd, 2006, 04:35	#24
Mr_Creepy Old Skool Join Date: May 2003 Location: In the O-zone Posts: 5,807	I went green needles from RDU to BOS once. That was a nightmare. __________________ "You know you're winning an argument with a liberal when they start calling you names" (insert any political group you want and stop calling me names) johntenney.com johntenneyracing.com Myspace

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