# Motor suddenly stop at mission

Hi everybody,
During a mission at minute 27min 54sec the engine stopped suddenly and I don’t know why.
This mission I have repeated several times before and I have not had any problems.

@Loren_DS I am sorry to hear of your crash. Unfortunately this was caused by the H_COL_MID parameter being set too high. This parameter is to be set for the PWM that corresponds to a collective blade pitch of zero degrees or a blade pitch angle that results in zero thrust. The autopilot uses this parameter to determine when the aircraft has landed. You can find the description on how to set this up in the wiki for swashplate setup.

Just to be sure please verify the collective blade pitch angle for H_COL_MID. I suspect it is more like 3-5 deg based on the range of collective min to collective max.

I’m sorry again but if you have any questions please don’t hesitate to ask

Regards,
Bill

Hi @bnsgeyer,
I have rechecked the collective with the H_SV_MAN = 3 and the collective value was +1.5 degrees.
Do you think that this little mismatch could have caused the engine stop?
The funny thing is that I had no problems on the previous flights.

Now it is already set to 0 degrees and will test tomorrow.

What are the blade pitch angles for H_COL_MIN and H_COL_MAX?

-5 degrees and +11.5 degrees

@Loren_DS Based on your min and max and your PWM values, I determined your H_COL_MID blade pitch to be 4 deg. See below

H_COL_MIN 1500pwm -5 deg
H_COL_MAX 1725pwm 11.5 deg

H_COL_MID 1625
blade pitch (deg)= (11.5 - (-5)) * (1625 - 1500)/(1725-1500) - 5
blade pitch (deg) = 4 deg

That is interesting that you are reading 1.5. that is significantly different from what the calculation says it should be. You might want to set that a little lower. the calculations say H_COL_MID should be 1568. I’m not sure why it would be that far off. It doesn’t hurt anything to set it a little low, especially since you are not using collective to yaw mixing (H_COLYAW=0).

Hi @bnsgeyer,
now i have this value:
H_COL_MIN 1520pwm -5º
H_COL_MAX 1755pwm +11.5º
H_COL_MID 1592pwm 0.0º

blade pitch (deg)= (11.5 - (-5)) * (1592 - 1500)/(1755-1500) - 5