A5 seal/flange in the engine

[sama_RA]

Hi all,
Would be grateful if somebody could explain to me what does A5 mean in the engine. For example A5 seal/A5 flange. Is there some kind of zoning?
Was trying to make my own search but with no luck.

Thanks in advance!

[Swedish Steve]

come on give us a clue.
Like what sort of engine. Lycoming GE90 Trent?

[lomapaseo]

Some engines name major case flanges starting with "A" at the very front. Of course if it's british they probably start at the back since they drive on the wrong side of the road as well

[sama_RA]

Thanks for your replies! It's a GE, the CF34 family, so with the flanges, there is a possibility they start at the front
The engine is CF34-8C5 to be exact.
I figured A4 stands for a fan case flange but having hard time with the A5 one.

[lomapaseo]

In my experience the flange in front of the fan blades is called "A" while the bolted flange behind the fan blades is called "B". Is it possible that there are stiffener flanges (without bolts) in between? Somehow I suspect that a maintenance forum would know the answer.

[john_tullamarine]

Of course if it's british ...

.. that's a tad cruel .. the Brits have it head and shoulders over the rest for robust construction .. surely we can permit some tolerance for strange numbering systems ..

[barit1]

My guess is that it's not an external flange at all, but an aerodynamic station in the main core flowpath. For example - depending on the vintage of the engine and the industry ID standard at that time - A4 could be the flow area of the stage one turbine nozzle. An A4 flange could be shorthand for the nozzle flange that (internally) holds it in place, and a seal at that location prevents (or reduces) parasitic air leakage.

But it's just a semi-educated guess.