Flight Meter Vs Hobbs Meter

I have heard a number of different takes on this and would like to see what your thoughts are in the Cirrus Community. If you are selling a Cirrus that has a Flight Meter and Hobbs Meter installed, are you using the Flight Meter for both airframe and engine times or the Hobbs? Interested to hear your insight and any applicable reference from Cirrus would be outstanding if available. Thanks in advance!

I have been involved with cirrus from the beginning. 90 percent of all talk , maintenance and selling we all refer to flight time. TBO is based on flight time also. Don

Thank you Don. Do you know if there is a reference from Cirrus that verifies this?

Chris, I can speak to this from an aircraft sales perspective. The industry norm is to use Flight time (when available) as the measure of engine and airframe time. There is plenty of historical precedent for this, as legacy airplanes have always had times quoted in “Tach” time, even when a Hobbs meter was installed. The rationale is that wear is accumulating on the airplane at a faster rate when it’s “working” (i.e., flying) than when it’s idling. Tach time and Flight time are very similar in this regard.

I don’t have a specific reference from Cirrus, but it’s also true that maintenance intervals, life limits, and TBO recommendations are governed by Flight time.

So then what’s the purpose of the Hobbs meter? Mostly for recording and logging piloting time, which always starts and ends at the chocks.

That and for charging renters. [;)]

Even in the jet world, it’s flight time that is used for maintenance intervals, even for the engines.

There is no mystery about this. 14 CFR 1.1 defines it.

“Time in service, with respect to maintenance time records, means the time from the moment an aircraft leaves the surface of the earth until it touches it at the next point of landing”

via COPAme