As I said, multiple turn-backs for the same frame inside a week are rare but not unheard of. Given the reason for the turn-backs, I don't agree that this is evi

As I said, multiple turn-backs for the same frame inside a week are rare but not unheard of. Given the reason for the turn-backs, I don't agree that this is evidence of an objective safety concern. Components are expected to fail in service, and do fail on all airlines and all aircraft types. The overall system design preserves safety despite these component failures. A fuel imbalance isn't an imminent danger to the aircraft or its occupants.