Found a shock on the A340 brake fan wiring diagram

Last week I was tracing a brake fan fault on an A340 and pulled up the old wiring diagram. The detail that surprised me? The brake fan controller has its own separate circuit breaker labeled in the MEL as 'essential' but it's not on the essential bus. I double checked the book twice. It's a small thing, but it changes how I'd do a lost bus drill. Has anyone else found a diagram that seems to contradict the bus listing like that?

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claire_walker20d ago

That 76-21-05 breaker has given me headaches too. I ran into a similar mismatch on a 330 a couple years back, where the MEL said 'essential' but the actual bus tie logic told a totally different story. It's frustrating when the paper and the plane don't line up, and you end up second guessing your own eyes. I ended up calling the engineer desk and they confirmed the diagram was right, the MEL wording was just outdated, but it still took me an extra hour to be sure.