Rolls Royce M250 chip lights
On the M250 engine, a couple of points to note.
1. the oil scavenge hole in the Number 1 bearing housing is very small, especially on the C20R engine. Number 1 bearing failure is normally only indicated by fine particles on the chip plug, as the bigger pieces are trapped in the housing. Don't ignore or take any chances with any tiny chips on the forward (top) plug.
2. Fine dust on the chip plugs normally indicates gear wear. What if the fine dust is caused by a gear shaft retaining ring, with the ring about to fail/cut through retaining wall?
3. There may be no debris on the plug because there is no magnetism. Chip plugs lose their strength over time. Every time you remove one, check it can pick up something like a washer sized item.
4. All Rolls Royce approved facilities can tell you the likely source of metal chips, if you have the debris analysed (or send it to them to have it analysed). Just let them know the AMS spec and which chip plug.