Yeah, I was about to write what Patrick did. If you do it properly, you don't lose a thing.

 

First, to clear a huge misunderstanding, the engines being on doesn't mean the GPU can't be taken out. Start both engines, switch to the GENs, disconnect the GPU, and go about your way.

 

As an example, the SAAB 340s are not very fond of being started off of the BAT, so you leave the GPU plugged in. They'll spin #2 at the gate, signal for the disconnect, a rampie walks under the wing from tip to fuselage, unplugs it, shuts the door and follows the same under-wing route back out. The #1 is started at the completion of the push.

 

As for the J41, the only difference is that you spin both engines at the gates.

 

The tutorial mentions that the J41 has a very tight turning radius, so turning out of a gate isn't a problem. If you're looking for what this looks like on a ramp, load up Google Earth, and go into History Mode and turn back the time at IAD. You'll see ACA's operation (part of the reason the J41 was modeled), and the somewhat awkward taxi lines on the ramp.

Patrick, Kyle,

 

thanx for your explanations.

Yep, with the GPU it works (if you don't forget to switch on the generators, cough, cough).

FMS is independent from avionics switches.

And the gyros come back quickly.

 

So, with no GPU available, we cannot prepare the FMS, except the flight plan.

 

Remains one question:

Why do we have to switch off the avionics for engine start? AOM states this as a matter of fact...

 

Thanx in advance.

Protects the avionics from spikes/surges, or something like that.

OK, Thanks guys.... I think the answer is to start both engines on the GPU ensuring both are generating before the GPU is disconnected. Two things though.... in the real world, ground handling are not going to be very keen wrestling with the GPU trolley with the right prop spinning and secondly, it means we need to park so that we don't need to push back - bearing in mind the huge red sticker on the panel telling us that pushback with engines running is prohibited.

 

She's a bit different this J41 isn't she? Guess that's what makes her so much fun! Definitely the preferred aircraft in my hangar.

Two things though.... in the real world, ground handling are not going to be very keen wrestling with the GPU trolley with the right prop spinning and secondly, it means we need to park so that we don't need to push back - bearing in mind the huge red sticker on the panel telling us that pushback with engines running is prohibited.

 

You're welcome. When people post things, you should perhaps give them a bit more of a read. I already answered both of your points here:

 

First, to clear a huge misunderstanding, the engines being on doesn't mean the GPU can't be taken out. Start both engines, switch to the GENs, disconnect the GPU, and go about your way.

 

As an example, the SAAB 340s are not very fond of being started off of the BAT, so you leave the GPU plugged in. They'll spin #2 at the gate, signal for the disconnect, a rampie walks under the wing from tip to fuselage, unplugs it, shuts the door and follows the same under-wing route back out. The #1 is started at the completion of the push.

 

[...]

 

The tutorial mentions that the J41 has a very tight turning radius, so turning out of a gate isn't a problem. If you're looking for what this looks like on a ramp, load up Google Earth, and go into History Mode and turn back the time at IAD. You'll see ACA's operation (part of the reason the J41 was modeled), and the somewhat awkward taxi lines on the ramp.

 

Colors matched to emphasize the questions and respective answers.

Yes, sorry Kyle... my intention was to acknowledge the answers you had provided, not ask the question again. sorry for the misunderstanding.

Yes, sorry Kyle... my intention was to acknowledge the answers you had provided, not ask the question again. sorry for the misunderstanding.

 

No prob. Sorry for being my typical pre-coffee grouch.

First, to clear a huge misunderstanding, the engines being on doesn't mean the GPU can't be taken out. Start both engines, switch to the GENs, disconnect the GPU, and go about your way

The above video would seem to suggest they start the left engine whilst on ground power (note the orange cable from the nose) and once it is stabilised they remove the GPU and start the right engine (same as the Saab 340 example you gave). This is how I've always done it in the sim when using ground power, and if you remember to turn on the left generator before killing the GPU supply and disconnecting it, the FMS will stay powered throughout the start procedure.

 

it means we need to park so that we don't need to push back - bearing in mind the huge red sticker on the panel telling us that pushback with engines running is prohibited.

The "pushback with engines running prohibited" thing I understand to be an airline SOP, it's not a restriction BAe placed on the aircraft. Many airlines also prohibited powerbacks, but obviously not Eastern on the basis of the same video.

 

EDIT: Another YouTube video seems to show ground crew going to disconnect the GPU after the left engine is started...

[...]

The above video would seem to suggest they start the left engine whilst on ground power (note the orange cable from the nose) and once it is stabilised they remove the GPU and start the right engine (same as the Saab 340 example you gave). This is how I've always done it in the sim when using ground power, and if you remember to turn on the left generator before killing the GPU supply and disconnecting it, the FMS will stay powered throughout the start procedure.

 

 

Yes, the left engine is started first because it's a pain for the ramp rats to have to walk under/around/out of the way of the propwash on the right side to get to the receptacle (which you can see is over on the right - #2 - side). The prop is blowing air back pretty quickly, and the engine exhaust can burn your hair off (don't ask how I know).

 

I referenced the SAAB specifically because that's how they do it on the SAAB, specifically. You'll note I didn't say they did that on the J41. I wasn't saying that's how it's done on the J41, rather, I was saying that even away from the J41, engines are started with the GPU connected, regardless of side.

 

The "pushback with engines running prohibited" thing I understand to be an airline SOP, it's not a restriction BAe placed on the aircraft. Many airlines also prohibited powerbacks, but obviously not Eastern on the basis of the same video.

 

Here in the States, it's an Airworthiness Directive (last I checked anyway), so no, not SOP, Federal requirement.

FYI, as an Avionics Tech and former RW pilot, I can reiterate what has been said above - the reason you turn the Avionics Switches off during engine start is you often get voltage spikes as starters engage and disengage. These can do everything from nothing to serious damage to printed circuit boards in components and other essential items that are powered up during engine starts. Of note too, power carts themselves can be responsible for voltage spikes if their internal limiting circuits are malfunctioning, so even they can be an issue. It's best (but not always possible) to hook up the carts with everything in the aircraft powered down, or if an aircraft has just arrived at a gate/stand, to at least power down the Avionics before hooking the cart up. The latter is not that often done though AFAIK. I'm working on an AFCS unit out of a Dash 8 right now that was hooked up to a "rogue" power cart and it blew out both voltage regulators in the AFCS.

 

Hope that helps.

 

Glenn Davy

<...> or if an aircraft has just arrived at a gate/stand, to at least power down the Avionics before hooking the cart up. The latter is not that often done though AFAIK.

 

Hehe, than FYI: That's standard procedure on our JS31/32's, avionic masters are in the shutdown flow & checks :). I seem to recall they are in the J41 as well.

I don't doubt it. For maintenance crews they are not supposed to change lamps in the Caution or Advisory Lights panels with power on the aircraft. The reason is that they accidentally squeeze a bulb too hard with their pliers, break it and end up shorting out the channel. That's when I get the unit so I can repair the transistors they just wiped out. Costs the airline a fair chunk of change to repair their actions, but they keep on doing it. SOP seems to be more a "guideline" for some :P.

 

Glenn Davy

The thread discusses also leaving the stand with the tight turning radius.

 

Well , the first of the two videos above shows that Eastern use the reverser to taxi out backwards.

 

Should be ok with the help of the ramp rat.

However, in FSX, don't brake too hard, else the J41 pitches up sinking into the apron... crash.