T-Motor MN2806 KV650 with Arducopter 4.2.x

Potential thrust loss and crash

Can anyone able to help identify the cause of the thrust loss during a flight? PMU, ESC, or FCU (4.2.3)?

this drone has been overall functioning well since 2022 July. Just last week, I did a very successful 25mins single battery flight indoor. Really does not understand where goes wrong.