Today let’s talk about how we usually identifying the fan blade numbering. There is always some argument on we should start the numbering counter clockwise, clockwise by looking at how engine spining with their leading edge of fan blade. As there is no right or wrong but it just a matter how the job are done correctly and safely.
It is best practice in maintenance to always start with counterclockwise for all type of engine such as RR, PW or GE. All fan blade marking should start at No.1 followed by their own No.1 annules fillet together with slotted key No.1
The reason for marking of each component of the LP compression section fan blade, annulus fillet and slotted key because each parts has a different weight. Even the spinner or we call it nose cone also have different bolts that vary in length and weight. This is to allow engine to operate in smooth and balanced operation. If a new configuration of parts from its original one to one replacement, it will most likely to cause unbalance and high vibration which would require trim balancing.
Most of trim balance are achieved by either adding or removing weights on the spinner.
Here are some examples on how we normally identifying the starting marking of number 1 fan blade.
Author – LIM WEEPING – Licensed Aircraft Mechanic B1.1 | B773/ER GE90 & TRENT 800 | LEAN GREEN BELT HOLDER |
GE90 – Fan blade 1 is identified by a dimple on the spinner.
RR Trent 700 – Fan blade 1 is identified by a small red marking on the spinner.
RR Trent XWB – Fan blade 1 is easily identified with the pre marking on the spinner.