BBJ engine options

[[email protected]]

I am trying to setup Pfpx for the BBJ and am only finding the 26 or 27k rated engines as an option. Is the 24k engine used on the BBJ or only the standard -700? Just wondering as the information I am finding only shows 26/27K engines for BBJ. Also is the fuel burn significantly different between the 24k and 26/27k engines?

[Mad_X]

Spencer I think the general rule is: if it is an 737 option the BBJ has the best selectable option .

For example, all avionic options are standard on the BBJ. The only thing extra would be the EVS.

[Fleng200]

The BBJ is not a -700 or a -800, it is a model on its own. Fuselage is -700, but the landing gear is of the -800 configuration. All because of the aux fuel tanks and
associated higher ZFW.
Engine wise there is a same difference, the 24k rate is no option for the BBJ.

[SK331]

The BBJ in the sim has 24K engines. Haven't checked the BBJ2.

[DDowns]

Correct, BBJ is 24K while BBJ2 is 26K with 27K bump.

[Emi]

The BBJ has the 26K bump available as well. Very helpful to get out of places like Eagle County or Jackson Hole!

[Calzonister]

Boeing has not delivered a single BBJ with a 24K rating. The BBJ 171,000lbs MTOW is only available with the 26K rating.

Meanwhile the BBJ2 can be optioned with either the 26K (with optional 27K bump) rating or a straight 27K rating.

Has anyone submitted a ticket?

[mikejones]

The BBJ is not a -700 or a -800, it is a model on its own. Fuselage is -700, but the landing gear is of the -800 configuration. All because of the aux fuel tanks and
associated higher ZFW.
Engine wise there is a same difference, the 24k rate is no option for the BBJ.

Along with the -800 gear, I believe the BBJ1 also has -800 wings as well. They're slightly larger the -700 wings.

Does anyone know about the BBJ2? Is it ust a fancy 737-800? Or does it have enhancements borrowed from other models in the family?

MJ

[DDowns]

As a minimum, both models have changes to the cabin pressurization system. The AUX fuel system is quite a significant change to the model. Lot's of details like the TIOS antenna make it a BBJ and not just a fancy -800.

[DDowns]

I'm appear to be wrong on the BBJ thrust, partly my error by assuming that PMDG beta version (which is now released) with 24K was correct. The BBJ FCOM was not available to us so today is my first look a that document and BBJ FCOM 7.20.4 clearly indicates EEC normal mode thrust limit is the CFM56-7B27 for both BBJ/BBJ2. So even the BBJ2 with 27K bump is wrong according to Boeing document.

I've also queried in the beta channel so lets see how this turns out.

[Calzonister]

To understand why the the 24K rating is not an even an option on the real BBJ, refer to the PMDG -700 FCOM Volume 1
This reflects a standard -700 with 24K rating.

Performance Dispatch page PD.20.2.

Note the Climb Limit weight at ISA (OAT +15C and Sea Level Pressure Altitude)
162,600Lbs with the 24K rating - Perfectly sufficient for a standard -700 with its 154,000Lbs MTOW

The -700 BBJ has a 171,000Lbs MTOW and that is why it requires a 26K rating.

[B777ER]

Great, so now we have a underpowered, unrealistic rendition for the BBJ. I hope they correct this soon.

[SK331]

Would have been nice to be able to select the base rating of the engine per livery basis.

[B777ER]

So the modeled engines on the PMDG BBJ are wrong?

[[email protected]]

I haven’t tried to fly with full payload and fuel yet so I am not sure how this will work out with the lower thrust 24k engine. Hopefully this can be addressed though.

[Airway88]

I agree BBJ is 26K and 27K engines only, not 24K, and as many others say the 24K engines are wrong on the BBJ due the Performance Limit on them etc..I hope this will be updated, it should be an easy fix for PMDG to change this, the engine rating in the CFG, and the FMC so it get`s the right engine option.

But I am very sure that PMDG will fix this in a small microupdate or so on the upcoming days

[DDowns]

The EFB performance calculator has to be modified... easy fix? Engine thrust is a factor in all performance calculations so the FDE stuff needs modified as well. This is much more than just changing the text on the FMC.

[Calzonister]

To be more specific, on both the real BBJ and BBJ2 the options are CFM56-7B26/B1 (26K rating) and CFM56-7B27/B3 (27K rating).

Most have opted for the -7B27/B3

[B777ER]

Very surprised this was not caught in beta. This is likely a few weeks to fix reference what Dan stated above. I'll stick with the BBJ2 until the BBJ is sorted.

[DDowns]

Not obvious during beta without the FCOM.

[AngelofAttack]

BBJ FCOM 7.20.4 clearly indicates EEC normal mode thrust limit is the CFM56-7B27 for both BBJ/BBJ2. So even the BBJ2 with 27K bump is wrong according to Boeing document.

Not quite correct, the EEC rating is different from "purchase" rating, for EEC rating, all -600 is rated 22K, almost all -700 is rated 24k, and all 8/900 are rated at 27k, BBJ1 at 27K then? That's what the engine could proved when pilot "firewall" the thrust levers, and shown as the little amber bar on N1 gaugue (and that little bar is yet another option) .

But for airline option, they can choose 22k on700 , 24 or 26 on 800 etc., in that case, the take-off N1 (Green bug) will always be lower than the amber bar if installed.
But still the pilot can firewall 27k of thrust out of a 24K -800 if it's really needed.

To complicated things, there are 26B1 and B2 available for -700, it performs the same at sea level when tempture is less than ISA+15 (flat rating braking point), but when it's high and hot, it squeezes more power (but still under the 27k rating (B1 for hot, and B2 for both high and hot)
Also, 27KB1 is avaliable for -800 and -900, which performes same as 27k when high and hot, but when tempture is lower than braking point, it can goes slightly higher.

Sorce from the CFM's Advanced Engine system class.

[DDowns]

Very interesting Zhu Hai... thank you for expanding this topic. To be honest, I've only one seen case in my several dozen BBJ sessions that had a performance limitation for takeoff and I had to offload a couple of hundred pounds. In fact, I flew a BBJ from NZAA to VMMC with full tanks (71 klbs) and six pax (no cargo) and it managed to get off the ground normally... didn't point to a problem with engine thrust.

[AngelofAttack]

I just had (acrtually still hundred miles from TOD,) a flight from Africa to Japan, with 5400nm range, and TO from HAMK, 7400' elevation, and 30C hot.
I thought full fuel will do it, but after calculation I'll over the MTOW limited by climb performece.
I ended up with 28.2t of fuel, and TOW at 71.8t, the EFB can only give me 24k TO at 57T, but PET can give me, wait for it: 26KB2, Bleed off, and Flaps5 with improved climb almost 10 knots above balanced Vspds...
The PET gives me 102.7 N1, but with PMDG's 26K Bump, it only gives me 101.0 of N1, that's the difference then.

BTW my PET data is for -700 26B2, not BBJ, but I'll call it's close enough then...

[Calzonister]

Dan,

Using the example I gave above with the 162,600 Lbs Climb Limit weight (-700 with 24K rating), this Climb Limit assumes OEI which is why the BBJ/BBJ2 requires the 26K rating (and optional 27K rating). With both engines operating its a non-issue as you experienced departed NZAA.

[GermanSpottingTV]

I hope that will be fixed soon. That is currently preventing me from buying. Bad that it wasn't noticed in beta...

[DDowns]

Like I said... we didn't have the FCOM in beta.

[DDowns]

Dan,

Using the example I gave above with the 162,600 Lbs Climb Limit weight (-700 with 24K rating), this Climb Limit assumes OEI which is why the BBJ/BBJ2 requires the 26K rating (and optional 27K rating). With both engines operating its a non-issue as you experienced departed NZAA.

Okay.... what both you and Zhu say makes sense. The increased MTOW is certainly a factor.
I've looked around on the internet to try to find ANYTHING but all of the Boeing marketing blather is about the BBJ MAX. Couldn't find anything on the Navy/AF C-40 (BBJ1). Found several references indicating CFM56-7B LOL. Finally found an aviation consultant with BBJ description in sufficent detail to confirm the use of a CFM56-7B27, not that that means it's the only option:

https://jetadvisors.com/boeing-business-jet/

[[email protected]]

Okay.... what both you and Zhu say makes sense. The increased MTOW is certainly a factor.
I've looked around on the internet to try to find ANYTHING but all of the Boeing marketing blather is about the BBJ MAX. Couldn't find anything on the Navy/AF C-40 (BBJ1). Found several references indicating CFM56-7B LOL. Finally found an aviation consultant with BBJ description in sufficent detail to confirm the use of a CFM56-7B27, not that that means it's the only option:

https://jetadvisors.com/boeing-business-jet/

So the BBJ uses the 26k engine and the BBJ2 uses the 27k engine, correct?

[DDowns]

So the BBJ uses the 26k engine and the BBJ2 uses the 27k engine, correct?

The reference I quoted, certainly not authoritative, indicates 27K engine for BBJ. Hope to hear something from PMDG on this topic after the weekend.

[AngelofAttack]

On my sample FCOM for BBJ from Boeing, all 3 BBJs are 27KB3.

[DDowns]

On my sample FCOM for BBJ from Boeing, all 3 BBJs are 27KB3.

Yeah, you prompted me to look further than my first reference to EEC limits and I found in BBJ FCOM (that comes from Boeing and is available with this product) that all three, BBJ, BBJ2 and BBJ3 have performance tables for CFM56-7B27B3. There are performance table for BBJ that include 24K and 26K derates, and for BBJ2 26K derates.

[Calzonister]

There are only two CFM56-7B rating plugs offered for the BBJ-1 and BBJ-2.

-7B26/B1 (26k rating)
-7B27/B3 (27k rating)

The rating plugs dictate the maximum takeoff thrust under normal operations (i.e normal takeoff and when not firewalling).

-24k and -26k (if applicable) FMC de-rates are all customer options. Point is the maximum 26k or 27k rating (depending on which plug was optioned) is always available.

Without the 26k rating plug, a BBJ-1 would not achieve anywhere near its 171,000Lbs MTOW as previously discussed.

If it’s feasible for PMDG, I suggest -7B27/B3 so that we have the full 27,300lbs as standard on both BBJ-1 and BBJ-2, with FMC selectable de-rates of 26k and 24k for the BBJ1 and 26k for the BBJ-2.

[alaaar]

Hello Spencer, Could you please share the PFPX profiles, I tried to develop some last night but I had many assumptions to make, unanswered questions and missing information, I am not happy and probably do not have the experience, thanks

[Fleng200]

FWIW. The BBJ is always delivered with the Short Field Performance package. That is not compatible with the low thrust ratings, as you need the higher thrust during T/O.
I did not see that the PMDG aircraft had 24k as engines, so there is is mismatch.
That will be reported (and fixed I guess).

[B777ER]

Let's hope PMDG give us an accurate version of the engine variations and not what we currently have. Whether I get flamed or not for saying this, I expect this from Captain Sim, not from PMDG who I hold in a higher regard.

[[email protected]]

Hello Spencer, Could you please share the PFPX profiles, I tried to develop some last night but I had many assumptions to make, unanswered questions and missing information, I am not happy and probably do not have the experience, thanks

Here you go. Includes the entire NG family as well.

https://forum.aerosoft.com/index.php?/files/file/2815-pfpx-boeing-737ng-performance-profiles-pack/

[CAPFlyer]

Let's hope PMDG give us an accurate version of the engine variations and not what we currently have. Whether I get flamed or not for saying this, I expect this from Captain Sim, not from PMDG who I hold in a higher regard.

The only reason you'd get "flamed" here is because of statements like that which are purposefully incendiary and not helpful. Instead, try keeping these comments to yourself.

[B777ER]

If reality is incendiary then so be it. Not everything is rainbows and flowers Chris.

[MattSweet]

Has PMDG acknowledged this issue yet?

[Airway88]

I thought they would have fixed it with the last update but no, still no 27K in the FMC only 24K...

[DDowns]

Have they replied to your support ticket that reported this to them?

[Airway88]

I have reported it already the same day it was released, I sent them a new ticket today to see if they respond to it..

[Airway88]

We still got no news if they will fix this issue, the support gave me an answer that if it is possible to fix it they will, but it was not high prioritized..

This is not good to be PMDG, they normally fix things like this easy and update it accordingly, but this time it seems like they don`t care about fixing the BBJ Engine isssue not even one of the developers have even answered to this thread to update us all, eventually a reason why they haven`t fixed the issue yet.

I hope they will fix it so we all get at least the right engine options..