Envoy off-roading at DFW

[STS-41B]

American Eagle Flight Veers Off Taxiway at DFW Airport

No one was hurt when an American Eagle jet veered off the taxiway shortly after landing Thursday morning at Dallas-Fort Worth International Airport, the airline says.

www.nbcdfw.com

 

[BigZ]

Rumor I saw is hard switch when shutting down 2 and APU still coming up.

 

[Autothrust Blue]

Rumor I saw is hard switch when shutting down 2 and APU still coming up.

Clunk.

Ding.

 

[msmspilot]

Rumor I saw is hard switch when shutting down 2 and APU still coming up.

So I’m not familiar with 170 systems... how would that cause an off-roading incident?

 

[bLizZuE]

So I’m not familiar with 170 systems... how would that cause an off-roading incident?

I’m not familiar either but this was an issue on our old 319/320s also.

 

[web265]

So I’m not familiar with 170 systems... how would that cause an off-roading incident?

It would be rare I think. Shutting down #2 engine for taxi with no APU is normal ops. It's done on most arrivals where there's time to cool down and shut down. (2 min cool down)

Having said that, I've seen on rare occasion where when a power source comes on / off line a bunch of electrically based EICAS messages appear with audible warnings which I guess could be a distraction.

Hyd 2 controls the nose wheel steering. When on the ground with engine #1 running and brake is released, the AC pump would be on (system logic, assuming the switch is in auto which is normal). It's powered by AC bus 1 so it is already running. If there was a momentary loss of electrical power, I would think the accumulator should give enough pressure to steer.

Also, half the brakes are on Hyd1 (inside? / outside? I forget) whose pump is running, and there's always the parking/e brake.

The warnings clear within a minute. In 3 years I may have seen this maybe 3-4 times. In the two times it happened moving, it did not cause a loss of brakes.

But not having been there, who knows.

 

[BigZ]

So I’m not familiar with 170 systems... how would that cause an off-roading incident?

Personally only saw a hard switch once, starting the engine after pushback. Right about where that side ac bus switches from apu to gen, we got lights shutting off and on, screens acting up, some things like CCD freezing for good, million cas messages. Ended up creeping back to the gate, getting mx to reset it, do test engine runs etc at the gate. Flew few subsequent legs on it, no issues.
Something like that would definitely kick the nose wheel steering off, normal brakes too possibly, until the computers had a chance to recombobulate themselves

 

[JordanD]

I feel like that'd be some pretty bad luck. I'd had my share of hard transfers but never while the aircraft was in motion.

 

[JordanD]

It would be rare I think. Shutting down #2 engine for taxi with no APU is normal ops. It's done on most arrivals where there's time to cool down and shut down. (2 min cool down)

Having said that, I've seen on rare occasion where when a power source comes on / off line a bunch of electrically based EICAS messages appear with audible warnings which I guess could be a distraction.

Hyd 2 controls the nose wheel steering. When on the ground with engine #1 running and brake is released, the AC pump would be on (system logic, assuming the switch is in auto which is normal). It's powered by AC bus 1 so it is already running. If there was a momentary loss of electrical power, I would think the accumulator should give enough pressure to steer.

Also, half the brakes are on Hyd1 (inside? / outside? I forget) whose pump is running, and there's always the parking/e brake.

The warnings clear within a minute. In 3 years I may have seen this maybe 3-4 times. In the two times it happened moving, it did not cause a loss of brakes.

But not having been there, who knows.

Don't forget the plane being in a pissed off mood for the rest of the day

some things like CCD freezing for good

I don't remember how but I figured out if you kept your finger moving on it for a while it wouldn't freeze. It was kind of funny looking at my FO's confused faces when right after it happened and they're like "what was that?" I was telling them "keep moving that cursor!" right away.

 

[BigZ]

I don't remember how but I figured out if you kept your finger moving on it for a while it wouldn't freeze. It was kind of funny looking at my FO's confused faces when right after it happened and they're like "what was that?" I was telling them "keep moving that cursor!" right away.

Meh. Power surge = call to MOC = back to the gate = mx comes out.

 

[roundout]

I’m not familiar either but this was an issue on our old 319/320s also.

I can't remember if it was on Le Bus or the 145 but I seem to recall an italicized note about not shutting down the engine while in a turn? Or maybe I'm smoking crack. Preventing something like ^^^ was the explanation.

 

[mshunter]

This is why I always make sure the APU is up and running before shutting down #2. When I was in the right seat I had this exact scenario happen on the north bridge going to the west side while making the turn, mid turn. The captain managed to keep it on the pavement by stomping the left brake, but just barely. We had a bad power switch, nose wheel steering disconnected, and a whole slew of EICAS messages popped up, then went away. We came to a quick stop, cleaned some s**t up, and continued on. I also make sure we ain't turning when I ask for #2 shut down. I'm going to do everything I can to never end up on YT or on the news.

The 175 is a fantastic airplane, but it does have a few quirks that'll bite you if you aren't paying attention.

 

[Skåning]

Sooo how about everyone stop single engines taxiing then

 

[Autothrust Blue]

I can't remember if it was on Le Bus or the 145 but I seem to recall an italicized note about not shutting down the engine while in a turn? Or maybe I'm smoking crack. Preventing something like ^^^ was the explanation.

I'm pretty sure that advice was buried somewhere in the 175 book at old-jerb too, although it's generally just a Bad Idea (R) to do those changes when you AREN'T on a straightaway to begin with.

The 175 is a fantastic airplane, but it does have a few quirks that'll bite you if you aren't paying attention.

Eeeeyep!

 

[scooter2525]

Sooo how about everyone stop single engines taxiing then

What’s wrong with shutting down one?

 

[roundout]

Sooo how about everyone stop single engines taxiing then

I don't think the issue is single engine taxi, I think the issue is hard power transfers causing a BSCU or equivalent to fart. If you only induce a power transfer when you're on a straight, or stopped, the likelihood of offroadage is reduced.

One time I was absent minded and commanded (don't 8 me, it's the FOM verbiage) the F/O to shut down a motor but the APU gen was about 2% from coming on-line. Nothing happened, but there was an awful lot of relays clunking there for a few seconds.

 

[bLizZuE]

I don't think the issue is single engine taxi, I think the issue is hard power transfers causing a BSCU or equivalent to fart. If you only induce a power transfer when you're on a straight, or stopped, the likelihood of offroadage is reduced.

One time I was absent minded and commanded (don't 8 me, it's the FOM verbiage) the F/O to shut down a motor but the APU gen was about 2% from coming on-line. Nothing happened, but there was an awful lot of relays clunking there for a few seconds.

It was my job to wait until the appropriate moment to shut down an engine even when commanded during a turn. Forgot more than once and just winced and hoped we weren’t in an airplane that had old relays.

 

[Dphoenix]

As a former 175 driver... curious what SOP is at Envoy re: hyd pump #2. We had limitations at Compass re: power transfer and confirming power transfer on electrical page/waiting 3 seconds for this reason as it could cause nasty unwarranted things, they also seemed rather paranoid about SE taxi nosewheel steering and for that reason we left hyd pump #2 in "on" and not auto (you'd turn it on as part of CA preflight, and turn it off in parking flow.) "in accordance with system logic" this wasn't strictly supposed to be necessary and when having jumpseaters from OO they looked at me like I had a hole in my head for manually operating that switch, as I understand they just leave it in auto and let it do auto things.

 

[Baronman]

Sooo how about everyone stop single engines taxiing then

How non-green of you.

 

[jynxyjoe]

Did he go offroading the same place our Colgan idiot did the first month in a Mesaba CRJ900? Inquiring minds wanna know!