|Quoting Gigneil (Reply 14):|
Do you mean the 4156 and the 4168? They're different engines
Gigneil, You are correct that they were sold as 4156 and 4168. I should have only used the 4168, there isn't a 4068! My bad!
Pratt Naming convention #XYZ
#=serier (e.g., 4000)
X=airframer (0=Boeing, 1=airbus, 2=McD)
YZ=thrust in thousands of pounds.
Pratt developed the combustor for the 4156 in a 4062. Why not! And it leaves the combustor certified for the 62k thrust level. I tend to default to calling them the 40XX as that was a bad habit in my old department in Pratt. Mea culpa. We'd refer to each family as the 62k, 68k, 90k, or 98k pw4000. oops. Recall that even if a thrust is an "upthrust" (e.g., the 62k pw4262), all of the lower thrusts become just derates (e.g., the 4156) of that engine family.
Now, technically, the 4156 and 4056/4062 are the EXACT same engine (if a generation 3 build. Earlier builds cannot be upthrusted to 62k, the fan and case aren't built for the stress), just with different interface points and of course computer logic. You can modify a 4056 to a 4156 in minutes for a few hundred bucks worth of parts. (Tubes, electrical connectors, and the Fadac logic chip.) Note: to go to the higher thrust might require different restrictors in the fuel injectors and other trivial parts. (But Pratt charges big $$$ for the higher thrust license and controls that but charging for the fadac logic chip.)
The 4056/4156 to 4062/4262 are all 94" Pratt 4000 series for 747, 767, A300, and MD11
The 4168 is the Pratt 100" diameter fan 4000 series custom for the A330
The 4084/4090 is the Pratt 112" diameter fan 4000 series custom for the 777.
The infamous 4098 kept the 112" fan (kept nacelle geometry) but had a reduced bypass ratio due to a larger core.
Note and appology to those in opperations: I understand you can't be this sloppy with the number. E.g., the mx on a 4156 is on a different schedule than a 4262 even though they are the exact same engine (exception fadac logic, signal connector, fuel connector, and possibly fuel injector restrictors) as they leave the factory! Same exact build of materials except for the parts mentioned.