Simple. Add an odometer instrument, that shows engine runtime hours.

I'll add the hours variable, but it's up to the pack folks to implement the instrument itself.

Umm... odometers measure travelled distance, not engine hours (https://en.wikipedia.org/wiki/Odometer)

We know this, but on the Discord we discussed that hours are more important as they affect the vehicle.

So a gauge rather than holding the engine in your hand?

Would certainly be more convenient to know how badly you've fucked up while still moving rather than pulling over or landing, then wrenching an engine or three. Also, it'd look really cool. (it also probably doesn't tell you if engine or oil is leaking, which doesn't make taking the engine out obsolete, barring droplet particles)

Added "engine_hours" variable in V19.2.0. This allows for the ability of an instrument with pseudo-odometer status. Now it's up to pack creators to make use of it.