Tach time vs Hobbs time
It's common to invoice students based on the Hobbs meter while service intervals depend on the Tach time (which relates to engine revolutions).
When entering flight details, you normally record the engine hour meter. For aircraft with a Tach timer fitted, this should be used because it determines the next service time. Otherwise, for aircraft fitted with a conventional Hobbs meter, use that. If an aircraft has both, use the Tach timer.


There may be some information you don't want to post publicly on your school website. The Restricted content area may be a good place to post this, and direct your students and members to it.