As pilot in command of an airplane I have to be assured that all the maintenance is done as both safety and legality require before I take to the skies. When I came on with this company they had a problem with missed maintenance events, so I made them an excel spreadsheet with conditional formatting to colour events close to due in bright alerting colours. Every once in a while a new thing that I should have been tracking but wasn't is unearthed, either because I set up the sheet based on the aircraft manufacturer's intervals and the component manufacturer had a more specific requirement, because the requirements are amended, because I made a false assumption or because I just plain missed something. Today it was determined, I think through researching an STC, that a particular check valve, if it was one of two particular possible models, is due for replacement ten years from the date of manufacture. I pulled off the panel under which the check valve lurked and determined with a flashlight and determined squinting that the part was of one of the specified model numbers, dash four. I don't know if the -4 radically changes the life expectancy of the part. I just relay this information to the AME.
And then I go and do some other things slightly more piloty. Or maybe less. I think it may have involved getting a return authorization for oxygen regulators that were adjusting themselves in flight, leaving two crew members with hypoxia in the first week we used them. We stopped using them after that.
And then back to the check valve. Dash-4 or not it still needs to be replaced ten years after manufacturing, so the AME goes back into the panel, with a flashlight and a mirror, hunting for a date. There's a straight line in the manufacturer's label that has been scratched off. Was that the date. I joke and ask him can't he determine the model year from the colour and styling? We kind of suspect that if this check valve were a Volkswagon Beetle it would have a split windscreen and tiny red tail lights. "I'll order one now," sighs the AME.
And then after I went back to my computer, the ops manager kicked me out for working too long a day.