Flight time Counter in SR 20

NewPilot wrote:

When does the counter starts to run ?

It depends on the installation in that aircraft, but normally it is airspeed activated.

Hi and weclome,

Cirrus aircraft don’t have tach counters (which are RPM-dependent), but only a Hobbs Meter. Hobbs Meters (meters made by Hobbs) are 99% activated by the engine running. RPM is not relevant. Battery on / off is not relevant.

Many newer Cirrus aircraft have two Hobbs meters, the second one being “flight time only”, but it doens’t sound like you have that situation.

BTW, you are lucky that your club charges flight time only. Many nowadays charge block time, because
a) they have the excuse that you can count block time (not only flight time) for your class rating revalidations
b) if they don’t use the Hobbs they would either have to install something that measures airborne time or otherwise rely on what the pilots writes into the book (contrary to what Peter might believe, many club in Germany work that way and there is a climate of trust and very few people misuse that).

Hobbs Meters are 99% activated by the engine running.

Usually coupled to the same sensor that activates the “low oil pressure” annunciator light, I seem to remember?

boscomantico wrote:

many club in Germany work that way and there is a climate of trust and very few people misuse that

Welcome, Newpilot

The answer is installation dependent. Why not post a photo of the “hours meter” fitted?

Some options:

• oil pressure (i.e. engine running time)

• counting engine revolutions (so will measure “hours” correctly only at say 2300rpm)

• the bus voltage being “up” (so will run only when the ALT circuit breaker is pressed in, and yes this is sometimes used by renters to cheat – I have met people who proudly told me they do it, with the main downside is that they have to fly non-radio )

• counts time only when the rpm is above say 1200 (that’s what I have)

As regards fairness of the resulting billing, the arguments run in every direction

contrary to what Peter might believe

I have never been in a German club, and I am sure there is a 50,000 DM fine for being more than 1 minute off

Peter wrote:

As regards fairness of the resulting billing, the arguments run in every direction

Well, one can note that maintenance is based on flight time, not tacho or Hobbs time. Also, fuel consumption on the ground for piston engines is usually negligible compared to consumption in the air. These two are the main time-related expenses.