t'aint natural,
There are many types of detectors, basically into three classes:
Plain vanilla mag chip, where a simple bridged contact lights the light. Can be with holding circuit to flag the momentary chip passing by.
Fuzz burn chip plug, where a capacitor dumps a charge into the chip to burn it if it is small stuff, to prevent the fuzz from alarming anyone.
temp and chip combination, where either a chip or a high temp can light one light, or a separate light for each.
Sikorsky helos generally have fuzz burn temp/chip lights. I'll wage the Robinson family has the less sophisticated plugs.
New technologies are being developed, with mag inspection of the oil as it flows thru the system, using a coil to pick up the changing magnetic signature of the oil.