Originally Posted by
Aussienarelle
I certainly understand the orange light is to help a passanger thar needs assistance in the lavatory and why it is okay to fly with the light bot working for 3 flights but not 4 was beyond confusing to me.
It's really simple. Because the MEL only allowed three flights.
Each MEL item has a designated time limit so that an airline can't defer a discrepancy indefinitely. It is listed in the "1. Repair Category" column as an "A", "B", "C", or "D". You can read more about Repair Categories on page 18 of this FAA document.
https://www.faa.gov/sites/faa.gov/fi...Coord_Copy.pdf
A 3-flight MEL would be Category "A" with the three flight limit specified in the MEL item description.
I don't know the details of the procedures which are used to assign Repair Categories to each item. They are worked out between the FAA and the Manufacturer during development of the MMEL.