# 3.3. CoG calibration

3.3.1. Fill the tank with mixed fuel.

<figure><img src="https://1851866520-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FIWx9bMxy88NRLPUcOemU%2Fuploads%2F9ceYIF3TD37CvSffbJX3%2F3-3-1.jpg?alt=media&#x26;token=ae93eea1-191d-40f9-abb0-2284f22da6f2" alt=""><figcaption></figcaption></figure>

3.3.2. Put the batteries into the battery compartment (do not power on the batteries).

<figure><img src="https://1851866520-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FIWx9bMxy88NRLPUcOemU%2Fuploads%2FroCbOxXRoBcYw72W1Ul9%2F3-3-2.jpg?alt=media&#x26;token=a33c0824-bb09-4f7a-9904-3f36ade1fc99" alt=""><figcaption></figcaption></figure>

3.3.3. Check the aircraft center of gravity.

<figure><img src="https://1851866520-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FIWx9bMxy88NRLPUcOemU%2Fuploads%2FMc2Ocazi2YnQBqTTdOia%2F3-3-3.jpg?alt=media&#x26;token=cf26016e-07fb-4518-8839-3f7e5c6c9f21" alt=""><figcaption></figcaption></figure>

3.3.4.Tight the batteries.

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