Envoy off-roading at DFW

Talking about electrical power surges being bad. So, we started using CPDLC to talk to enroute ATC and get clearances. I'm sure you've heard of it. Some glitch in the system caused some bad clearances to be followed from a previous flight. How to fix that? Making sure the ATC log is erased wasn't good enough. After each flight our shutdown checklist has us kill power to the entire airplane for 10 seconds to make sure everything is erased from the memory. I've never seen so many status message pop up once the power comes back on. Big relays going click and clunk. Just can't be good for the airplane...
 
The 737 is weird. We taxi out on #2 and taxi in on #1.

And surprisingly, generator transfers on the 73 are pretty dead quiet. On the Bus I’d push that button and prepare for a KER-Klunnnnnk!
 
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
Interesting. The CRJ occasionally has an issue when power switches, but nothing to that extent. Usually just roll your eyes and turn yaw damp 2 back on.
 
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.
Plane manufacturers since T-Fans were introduced be all like, "There is nothing in the AFM checklist regarding shutting down engines during taxi. We can not be held accountable for operator shenanigans. Carry on."
 
Interesting. The CRJ occasionally has an issue when power switches, but nothing to that extent. Usually just roll your eyes and turn yaw damp 2 back on.
The E175 grew on me substantially over the last year (have around 600 hrs on it now), but overall C700 I was on before was simpler in system design and more complex to operate. This plane is kinda overengineered in some ways, but that makes for less button pushes. Nosewheel steering reset is like a one second thing that doesn't require circuit breaker pulling etc and so far we only had to do it once, was a bit more common on crj
 
Sooo how about everyone stop single engines taxiing then
I'd do it pre-takeoff when conditions warranted to save fuel I wanted down the road... but I think I hardly ever did it on taxi-in. The gas savings were never worth the rut that I always inevitably got stuck in, or the marshaller stopping me, killing my momentum, then suddenly realizing he needs to marshal me forward another 2 feet and I can't get it moving again. Even pre-departure it was a "if there's a huge line" kind of thing. Unless you were sitting there idle for an appreciable amount of time I seemed like the fuel savings were negligible or non-existent when you're having to use twice the power on #1 just to get rolling.
 
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.
I never was fully comfortable with the fact that we left it to the “system logic,” but never mind me.
 
Talking about electrical power surges being bad. So, we started using CPDLC to talk to enroute ATC and get clearances. I'm sure you've heard of it. Some glitch in the system caused some bad clearances to be followed from a previous flight. How to fix that? Making sure the ATC log is erased wasn't good enough. After each flight our shutdown checklist has us kill power to the entire airplane for 10 seconds to make sure everything is erased from the memory. I've never seen so many status message pop up once the power comes back on. Big relays going click and clunk. Just can't be good for the airplane...

That seems like a normal part of the CPDLC learning curve. I think we've been using it Oceanic for 6 years now, and for clearances ever since KUSA was a thing domestically. The empty the message log seems sufficient, but I do remember reading about some other procedures early on.
 
The 175 is steer by wire, and a hard transfer can cause a steer fail. Hard transfers don't happen often, but going from on side engine to cross side engine as the APU comes up to provide power can definitely do it.

Single-engine taxi can save some gas, though usually I'm more concerned about that on the taxi out than the taxi in.

At the end of the day, our shop used to shut down #2 as soon as the cooldown had elapsed, APU or not. But we also used to pull into the gate with the APU down, so we needed the right side to be down and the left side up until the GPU was plugged in, so it made sense. (AnD DeLTa iS MoNiTOrInG aPU RuNTiMES!!!11)

These days, we're expected to have the APU in approaching the gate, which is better all around. Given that, there's really no reason not to wait for the APU to be up and stable before shutting down the second engine. I usually shut down #2 while pointing into the gate and slow to keep things simple, unless I have a long, long, long taxi in front of me (Hi, 9L/27R)

The reason we don't routinely shut down #1 instead is that system logic expects single engine taxi with #1 running—starting engine #1 with engine #2 off turns on ACMP #2. However, starting engine #2 with engine #1 off does NOT start ACMP #1, and you're down a hydraulic system until you start #1.

The E-jet is actually extremely consistent in performance across the fleet, as far as I've seen. There are a few little techniques to stay inside the meat of the envelope, operationally speaking.

Also, I admit it's always shocking to see anything in American colors running off a taxiway... I'm so used to mainline American taxiing so slow that drag will bring them to a stop...
 
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