skunkwurk

My Feedback: (18)

Hi Fellas,

I'm going to share my "dumb maneuver for the day" with you and ask your opinion. I powered-on my jet today with my tail covers on the vert-fin and stabs. I didn't even think of removing them as I was only intending to check a setting on the gyro. When I powered-on I immediately heard one of the elevator servos whining, I checked and noticed the cover was binding one servo from centering. I tried to correct it but the cover was being held pretty tight. So I turned the plane off and removed the covers. I have tested and tested the servo and it seems to work fine. I didn't notice any dreaded electrical smell either.

- Has this happened to anyone else? or am I just lucky...
- Should I be worried about the servo?
- Are there any tests I could perform to reassure myself it's unharmed?

I've seen a lot of servo stall and torque tests on servos, this is a JR 8911hv, they seem to hold up to abuse pretty well. There is a little play at center when powered-off, but I'm pretty sure that was there before... ugh...

Anyway, plz let me know your thoughts and recommendations. I don't want to fly a potentially unsafe or compromised setup.

Regards,

sc

FenderBean

If it was just for a short period I think you should be fine, you would know if the servo was damaged. Check with the power off if it's smooth and moves like it should most likely the servo motor is fine.

skunkwurk

My Feedback: (18)

Hi Keith,

Thank you, I appreciate the feedback. Yea I think you're right. I start to worry and get all worked up when something like this happens.

sc

SECRET AGENT

My Feedback: (18)

Turn the plane on, watch the stab halves move together listening and watching for any difference. If they are identical I wouldn't sweat it.

FenderBean

When the motor is damaged you can deff feel and hear a difference. Ask me how I know

skunkwurk

My Feedback: (18)

Hi,

ok, I will try that, thank you.

sc

skunkwurk

My Feedback: (18)

lol... I will try and see if I notice a difference. The only difference I've noticed so far was the play at center.

These servos are notorious for developing play there, there is a little metal bushing that sits in a plastic pocket in the top cover, the pocket apparently widens over time.

tp777fo

My Feedback: (28)

Ive stalled lots of JR servos over the years and never destroyed one doing it. If you didnt let the smoke out of it then go fly. I will be fine.

skunkwurk

My Feedback: (18)

Sweet - thanks Tom.

sc

mauryr

I'd check you didn't cause any mechanical damage to the linkage or the structure though.

LGM Graphix

My Feedback: (22)

I've done the same thing in the past and for me, when I do something like that I stress over that servo forever. So that servo gets replaced and either goes into a sport plane or onto a less critical control like a brake valve. An 8911hv on a brake valve or sport model throttle might be overkill but if a tooth or anything is damaged I'd hate to lose a 5k + jet over a $250 servo. For myself I'd have to at least send it in to get it checked.

big fred

Would you chance your jet for the cost of one servo? Replace it.

gmeyers

I used to sell servo's but limit myself to just suppling locals with what they need to get in the air or finish a project. Servo's stall when they go beyond the limit of the gears - sometimes the pinion gear or driving gear gets damaged but the small amount of damage will likely not affect the performance of the servo. BUT whatever caused the servo to move beyond it's preset limit may still be there. I would swap that servo with one that won't cause a crash like the throttle servo or replace it completely til you can more thoroughly check it out.

[email protected]

Back there you were told to "check with the power off". I assume he meant for you to turn the servo arm manually nd look for normal movement.
NOT RECOMMENDED. There is no standard, but there is a very high gear ratio between the motor and the output gear, which places high loads on the gear's teeth. Obviously, this is more of a problem on plastic gear equipped servos.
Reversing the operation multiplies the gear ratio, and greatly increases the force on the gear's teeth, sometimes breaking some or distorting them enough to cause erratic operation.
Forcing the servo into reverse operation will not prove anything anyway. The gear train is working in reverse, which is not the way it rotates normally, the way it is intended to.
Otherwise, the advise to replace if in doubt is good.

paulhat

I really dont know if this applies to modern quality servos. I never follow this rule and to date have not damaged a servo (from what I can tell anyway).
For example, before each flying session I like to manually check control surface movement. I am never particularly gentle when doing this and have never stripped a gear/damaged anything.
For cheaper servos its probably a different story.

skunkwurk

My Feedback: (18)

Hi Guys,

I took the recommendation provided and tried to determine if there was any difference between the left and right elevators with power-off and also by running the elevators for a little while in the shop. I ultimately decided to trust it and had two great flights today. I think I may still ultimately move the servo to a different spot or just replace it.

Thanks for all of your great advice.

sc