Originally Posted by
Andrew2487
Any experience from you all, greatly appreciated !
To add to the above…
There are mainly two different time values (flight time & time-in-service) found within ICAO and other CAAs, each with their own definition and usage. However, in general, most CAA guidance allows a single recording method for both requirements.
In the case of maintenance tracking, ie., engine times, the preferred value and definition is time-in-service (TIS) as it gives the best bang for buck on maintenance related costs. However, since true TIS can be harder to record, the best conventional method for mx would be to use TACH time if you have a recording tachometer.
The reason is a mechanical tach is calibrated to a specific RPM and is only accurate at that RPM. So any slower engine run time like during taxi will be “prorated” at the slower RPM. But its closer to true TIS. Unfortunately with a digital tach you will lose most of that "prorating."
The least preferred conventional method to record mx TIS would be using a HOBBS especially if you do not have an oil switch in line to only record with the engine running. However, if you want to record flight time or charge for flight time the HOBBS is the better option as it gives you more for your dollar. If that makes sense.
That said, the most accurate method to record mx TIS would be to have a HOBBS with a wired squat or WOW switch that would only record true TIS once the wheels broke ground. Unfortunately if you used this method for flight time it would cheat you based on that accepted definition.
Or you could go old school and simply use your watch for all times.