Short summary
Hi everyone,
I’m looking for help analyzing a crash from 00000002.BIN.
Setup:
- ArduPilot Quad X
- Matek H743 Slim FC
- DB4 ELRS receiver
- RadioMaster TX16S
- ELRS/CRSF
- Nomad WiFi telemetry + Mission Planner
The flight initially hovered normally at ~9.2 m with ~30% throttle. At approximately 124 s, the log began showing repeated:
“Throttle failsafe on, RC Short Failsafe: switched to QLAND”
The failsafe cleared after roughly 0.3–0.4 s and returned to QLOITER, repeating about every 1.4 s.
At approximately 136.4 s, the aircraft suddenly became uncontrollable. M3 went to ~1949 PWM while M4 went to ~1150 PWM, followed by a rapid roll and crash.
I would like to understand whether the ELRS/CRSF short failsafes could have contributed to the loss of control, or whether the later motor-output pattern points to an independent motor/ESC/propulsion problem.
I’m particularly interested in:
- Correct interpretation of the M3/M4 output pattern for ArduPilot Quad X.
- Whether the repeated RC short failsafes indicate an ELRS/receiver/CRSF/UART problem.
- Any known ELRS DB4 / TX16S / CRSF / ArduPilot failsafe bugs or compatibility issues relevant to this setup.
- Whether Nomad/Mission Planner telemetry could have any interaction with the RC link.
- What additional log parameters or ground tests should be checked before flying again.
BIN log: 00000002.BIN is attached.
I’m especially interested in determining the first actual fault in the timeline, rather than assuming the crash was caused by either the motor or ELRS without evidence.