Tach and Hobbs meter numbers are critical for determining when certain aircraft inspections are due, when airworthiness directives need to be complied with, and how much the customer will be billed for the flight. [Credit: Meg Godlewski]
Key Takeaways:
Pilots must diligently check Hobbs and Tachometer numbers as they are critical for accurate billing, personal logbook entries, and ensuring compliance with maintenance schedules like Airworthiness Directives (ADs) and 100-hour inspections.
The Hobbs meter records total aircraft operating time, used for billing and logbooks, while the tachometer measures engine operating time, essential for maintenance tracking, typically showing about 20% less time than the Hobbs.
Flight schools employ strategies like tracking software and staggered scheduling to manage aircraft maintenance based on these times, sometimes grounding planes near inspection limits or having CFIs fly to "time out" an aircraft.
An aircraft past its 100-hour inspection (but within its annual) can still be legally flown by a pilot for personal currency, provided the flight is not for hire or flight instruction and no ADs are overflown.
I wish I had a dollar for every time I was asked this, or asked someone else this. These numbers are critical for determining when certain aircraft inspections are due, when airworthiness directives (ADs) need to be complied with, and how much the customer will be billed for the flight.
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Meg Godlewski has been an aviation journalist for more than 24 years and a CFI for more than 20 years. If she is not flying or teaching aviation, she is writing about it. Meg is a founding member of the Pilot Proficiency Center at EAA AirVenture and excels at the application of simulation technology to flatten the learning curve. Follow Meg on Twitter @2Lewski.
