Another way to check the rate of change from the Totalizer to Calculated is as follows:
First take note of Calculated value and Totalizer value.
On the PERF INIT page, type the Totalizer value onto the scratch pad and line select it over Calculated figure then execute. 'MAN' will replace 'CALC'
Then select DELETE and line select over the same figure and execute. 'CALC' will return.
Now they are synched. Then each hour you can monitor the rate of change.
You will be surprised how much this the rate does vary over a long flight.
halas