A VHM (Virtual Hour Meter) tracks hours only. It usually updates when you add hours to the aircraft’s main hour meter (“tach” or “Hobbs” meter) though a VHM can be independent and updated manually.
A maintenance item can track calendar days by itself and you can simply set it to come due at a certain date or you can set it to come due in a certain number of days. You can also set it to come automatically come due again in a certain number of days in order to keep track of recurring maintenance tasks.
If you want a maintenance task to come due at a certain number of flight hours you need to “hook” that maintenance task to a VHM. Once that task is associated with a VHM you can also set it to come due at a certain number of hours. A task can come due at a certain date or a certain number of hours, whichever comes first.
A task can come due at a certain number of hours regardless of date and, once that maintenance task is completed, it can be set to automatically come due again in a certain number of hours.
Posted in: SquawkLog User Tips