Circuit breaker for Hobbs meter on DA40 NG

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airwork77
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Circuit breaker for Hobbs meter on DA40 NG

Post by airwork77 »

The Hobbs meter on my DA40 NG has been erratic. Which circuit breaker is the Hobbs meter on? The circuit diagram indicates that it's connected to a 1 amp circuit breaker, but I don't see any 1 amp breakers.

Not sure if this is NG-specific, I know on the DA40 NG the hobbs starts as soon as the master is turned on (I believe the non-NG models it uses an oil pressure switch).
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Rich
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Re: Circuit breaker for Hobbs meter on DA40 NG

Post by Rich »

I see a fuse, not a CB, in the Wiring Diagram. It's likely where the fuse is for the other DA40's - in the engine compartment. The way the fuse holders are constructed does make it possible that the connection there could be flaky if the fuse cover is not tightened correctly.

The Hobbs meter has long been used to clock hours for purposes of billing renters for the aircraft time, so a ready way of disabling it is not provided.

UPDATE: Looking again at the wiring diagram, the fuse shows as in the instrument panel. Presumably out of view behind it somewhere.
Last edited by Rich on Wed Jan 05, 2022 3:38 pm, edited 1 time in total.
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chili4way
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Re: Circuit breaker for Hobbs meter on DA40 NG

Post by chili4way »

On the DA40NG, the Hobbs meter runs when the Engine Master is on (even if the engine is not running, e.g. when you're downloading EECU data). On the DA40NG the Service Hours meter (which is used for measuring MX intervals) runs when the airspeed is greater than ~35 KIAS. Airspeed substitutes for the landing gear "on ground" sensor found in the DA42NG and DA62. This means, on a DA40NG, you can connect your plane to a GPU, turn on the Electric Master, and explore the G1000 NXI without accumulating Hobbs hours. On my 2019 plane, with its flight profiles, the ratio of Service/Hobbs is about 77%. YMMV.

Interested to know what "erratic" means?
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