Here's the thing.... at the gate with the GPU attached and providing power, I program the FMC.... then, following the correct start procedures, if I disconnect the GPU in order to push back with engines OFF.... the FMC also switches itself off. One I'm pushed back and start the engines, when I re-apply power to the avionics (I have to switch the FMC on independently), and all my previous programming is lost, and I have to start again. I've been getting round it by leaving the GPU connected and starting the engines at the gate with both avionics switches ON... but that can't be right, surely? What am I missing?

Here's the thing.... at the gate with the GPU attached and providing power, I program the FMC.... then, following the correct start procedures, if I disconnect the GPU in order to push back with engines OFF.... the FMC also switches itself off. One I'm pushed back and start the engines, when I re-apply power to the avionics (I have to switch the FMC on independently), and all my previous programming is lost, and I have to start again. I've been getting round it by leaving the GPU connected and starting the engines at the gate with both avionics switches ON... but that can't be right, surely? What am I missing?

 

Start one engine at the gate/parking spot. It may be a stupid question, but are you turning the batteries off?

Hi Kenny.... no, batteries are on. I'll try starting the left engine and switching the left generator on before disconnecting the GPU - don't want to slice and dice the ground crew as they wheel the GPU trolley away do we?

 

Thank you for your reply.

I'm not sure about the J41, but on the J31/32 it's the same.

 

Avionics Masters off means that any GPS system that's linked to it will have to reboot as well (as far as I'm aware and have experienced). Some types might use a kind of memory system since they can switch off and with a relatively fast engine start they will have retained the data after turning the avionics on again.

 

One way around this is to perform the startup with avionics masters on (when starting with GPU). On the J31/32 most if not all systems are protected against voltage fluctuations that might result from engine start, with sometimes the exception being the TCAS. Turning the avionics masters off is just an extra precaution. You might want to try doing a startup without turning the avionics masters off to see if it has any adverse effects on the J41. It might of course, since it has more electronics in the cockpit than a J31/32, but still. In fact, I'll give it a go myself later tonight I think.

 

Edit: Another option is to start at stands instead of gates, with options to just turnaround for taxi under own power. This will probably be the more 'realistic' option anyway, since I don't expect many J41's to truly use gates (might be different in the US). But that can be a PITA with FSX, I know.

Yeah, but the AOM requires (without exception) to switch off the avionics before engine start (I think because to limit the GPU or batteries load).

Have I misunderstood the AOM?

If not, this means as tasks *after* engines start

- Avionics master on

- FMS on

- reload the hopefully stored flightplan

- choose the take-off runway

- choose the SID

- choose in NAV the first LNAV waypoint

- enter in VNAV the cruising altitude (at least)

- enter the reserve fuel

- enter the payload

 

A lot of tasks to do with the engines running and the gyros realigning.

Is this really the right procedure?

Yeah, but the AOM requires (without exception) to switch off the avionics before engine start (I think because to limit the GPU or batteries load).

Have I misunderstood the AOM?

If not, this means as tasks *after* engines start

- Avionics master on

- FMS on

- reload the hopefully stored flightplan

- choose the take-off runway

- choose the SID

- choose in NAV the first LNAV waypoint

- enter in VNAV the cruising altitude (at least)

- enter the reserve fuel

- enter the payload

 

A lot of tasks to do with the engines running and the gyros realigning.

Is this really the right procedure?

 

It has more to do with protecting the avionics more than battery/GPU load. The FMS should be programmed before engine start. You shouldn't be wasting time and gas programming the FMS with the engines running.

 

I tried the OP's situation a few days ago and it worked for me. Try running the tutorial again. If I can just remember that procedure exactly...

Yup, if the flight plan is stored, it is quite manageable:

You have three minutes time until the gyros are aligned.

So, the paper work and load sheet stuff including the different choices mentioned above can be done before engine start,

the inputs into the FMS afterwards.

 

Additionally: Are the three minutes engine run time acceptable, because oil temperature and hydraulics are then in a better condition?

(I think helis have such contraints, have they not?)

 

It has more to do with protecting the avionics more than battery/GPU load. The FMS should be programmed before engine start.

 

Kenny,

the AOM requires to switch the avionics OFF before engine start.

The FMS belongs to the avionics, consequently it is also off for and after the engine start.

 

So, my listed inputs have to be done *after* engine start.

Or do I get something wrong here?

So, the paper work and load sheet stuff including the different choices mentioned above can be done before engine start,

the inputs into the FMS afterwards.

 

I guess you could do that if you want to loose some fuel. Me, I'd rather take the conservative route and have as much fuel as I need (maybe a little more shh... don't tell the CP what I'm doing with the virtual company credit card :Big Grin: )...

 

Are the three minutes engine run time acceptable, because oil temperature and hydraulics are then in a better condition? (I think helis have such contraints, have they not?)

 

I think that requirement is on jet engines only. But that is something interesting I may have just learned. But I'd let the engines sit at idle taxi thrust for a few minutes just to be on the safe side.

 

Or do I get something wrong here?

 

I remember starting the engines on the J41 with the FMS on with no ill effects to navigation or anything. But I think a trip back to the manual would be in order for me because I'm drawing a blank here. :Nerd:

Kenny,

 

Tutorial p56:

'To get the airplane ready to start, move to the overhead panel and do the following:

- Turn both fuel pumps ON.

- Turn off both Avionics Switches

- Ensure both batteries are ON. (BAT lights will be illuminated when on GPU)

- Turn the BEACON and NAV lights ON.

- Turn the seatbelt and NO SMOKE signs ON...'

 

p60:

'After Start

Once started, run through the following steps on the overhead panel:

- Turn both fuel pumps OFF.

- Turn both Generators ON.

- Turn GPU switch OFF.

- Turn Avionics switches ON

- Turn Emergency Lights Switch to ARM. (Move guard first!)

- Turn Windshield Heat ON

- Turn Air Data Heat ON'

 

AOM:

 

'H. Before Start Check

Chapter 4 - Normal Procedures & Profiles

Before Start Check

Aircraft Operating Manual

46

1. The before start check must not be initiated until all paperwork is completed and the flight attendant has stated Cabin Secure”.

2. Just prior to engine start and/or pushback the Captain calls, “Before Start Check”.

a. First Officer’s Before Start Flow

a) Cabin Cooling/HeatlRecirc Fan

(1) Verify the vapor cycle air conditioning, auxiliary heat, and recirculation fan are OFF.

 

Beacon/Navs

(1) Turn the beacon ON and ensure the navigation lights are ON. The navigation lights should be selected to “tail flood” if it is nighttime.

c) Avionics Masters

(1) Turn off the avionics master switches....'

 

p57:

'b.

First Officers After Start Flow

a) Stand-By Pump

(1) Switch OFF the applicable FUEL STBY pump.

 

Generator

(1) Check the applicable generator output to verify it is between 27.5 - 29 volts; turn the generator ON.

c) Ground Power switch

(1) If used, turn off the ground power.

d) Avionics

(1) Switch the Avionics Master switches to ON....'

 

 

Next the FMS is mentioned on p64 in the expanded taxi check:

'(2) Check the FMS is in navigation mode by looking in the sub-page menu or by selecting LNAV, and verifying the absence of the “DR’ warning.'

 

Well, ...

Is it possible that you real J41 drivers keep the avionics switched on?

 

So.... for now, then... best practice is to program the route and save it... follow the AOM for start up and start the engines with avionics OFF, once the engines are stabilised and generating, turn the avionics and the FMC back ON, re-load the saved flight plan and finalise the PLAN and VNAV details - which are NOT saved with the route - during engine run-up and taxi.

 

Funny though, I've flown as a passenger, Leeds-Bradford to Aberdeen-Dyce hundreds of times... I don't ever remember being sat for long with engines idling, but then, they have two crew, of course, we only have ourselves.

 

Interesting topic though... Perhaps we can get some input from Capt. Randazzo, as he's logged a few thousand hours in these birds, guess he's the guru.

Drew,

 

The FMC is not on the avionics switch, it seem to be independent. I once lost the FMC - found it later when I turned a generator on - and it saved the weights (fuel and payload), but not the VNAV stuff. A second crew member would be nice....but then I would fall asleep :Just Kidding:

 

Regards

Drew,

 

The FMC is not on the avionics switch, it seem to be independent. I once lost the FMC - found it later when I turned a generator on - and it saved the weights (fuel and payload), but not the VNAV stuff. A second crew member would be nice....but then I would fall asleep :Just Kidding:

 

Regards

second crew man is fscrew2 :)

Some airlines start the left engine and gen first. Then disconnect the GPU and start the right

engine and gen. Then they reverse out of the gate.

 

R. Shedd

Robert,

 

the questions are whether

 

1. avionics are switched off in the start procedure (3 min re-align of the gyros after switching on again)

2. this also switcheds off the FMS (inputs after engine start)

 

Any real J41 jockeys out there? 8^)

Okay, I'm not sure what's going on here. This is how it should work. I'm going from a couple years ago memory so I may be off. I'll try with PMDG's J41 soon.

 

For a GPU Start:

Cold & Dark

Batteries on

GPU on and warmed up ;)

GPU switch set to Batt Assist or GPU on (Batt Assist is a rare option)

28V DC systems should be all powered up through the external power contactor, which will provide power to the cross-tie busbar, closed the cross-tie contactors and powers both left and right essential DC busbars.

You should be able to play with your FMS now no problem. It is typically powered through the left essential DC bus-bar (Gotta look up the manuals..can't quite remember). There's a couple different installations depending on type of FMS used (GNS-XLS vs. Universal vs. good ol' KLN90B) and regulatory requirements.

Inverters on to get those AC bus' all powered up.

Avionics on. Let the AHRS do it's thing. the AHRS has a quick-align feature, so even when the Avionics bus' are shut off for start, the pilot side AHRS should be up and going right away.

Now for start:

Avionics off. Keep GPU and Batt power on.

Start engines.

Gen's on before opening the External power contactor. (GPU off).

Avionics on.

 

Shouldn't lose FMS stuff and left EFIS/AHRS should be all aligned. Co-pilot side will align quickly.

 

I'll try it out in FSX.