Originally Posted by
Concentric
When you get a chip indication how many metal chips do you know there are?
The obvious answer is, "enough ferrous debris to bridge the sensor gap".
In reality, magnetic chip detectors are mostly helpful at detecting the types of gear/bearing failures that are not catastrophic. Modest surface spalling failures rather than fracture failures.
Emergency lube systems are designed to keep a gearbox functioning in the event a loss of lube oil flow occurs. Assuming everything else in the gearbox is still working OK.