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Old Mar 18, 2013, 06:59 AM
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Rcflyyer1's Avatar
United States, FL, Sarasota
Joined Dec 2010
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Hitec Servo Failure

Hi all, so last Sunday I was flying my Great Planes Escapade 40 which was fitted with my Hitec HS-485HB. The servo was not old at all. When I bought the servo, I believed that it should be sufficient to move a 40 sized sport airplane's elevator.

I have had 3 crashes, all the failure of elevator control and the 2nd and 3rd are blamed on the Hitec servo. On the 1st one, the clevis broke which ended up in no elevator control. The 2nd one was an elevator servo failure. I took off, did one circle in the pattern then lost the elevator on the downwind. Luckily, the grass was very soft that day and the plane wasn't totally destroyed so I repaired it.

The 2nd plane had a Hitec HS-311 which was determined to be the motor failure in the servo. The 3rd plane had a Hitec HS-485HB Deluxe servo. Again on the little 40 sized elevator. I fly it for a few months thinking everything is going well and it probably won't have any failures again but then suddenly, as I come in for a pass over the runway at about 15-20 feet in the air, suddenly I notice the nose pitching down, so I apply up elevator more and more and more until I am at the bottom of the stick. It wasn't signal loss since I still had aileron, rudder and throttle control. We tested all the servos after the crash and they all worked except for the elevator servo. The elevator servo would buzz when I tried to move it but wouldn't keep the arm still as I could move it in any direction I wanted to. Everything was plugged in too and we even plugged the bad servo into the throttle port and again, no control when we moved the throttle stick.

The crash into the runway totaled the airframe. The electronics are fine so I would really like Hitec to explain the loss of 2 airplanes with 2 of their servos having the same identical problem. My Futaba S3004 servos don't seem to fail on me, in fact I have been flying 10 year old futaba servos without any problem. A lot of the flyers up there were shocked and had changed views on Hitec. We also have a lot of IMAA flyers with huge airplanes at my field and they were surprised to see a Hitec servo fail 2 times in the identical way. The servo failure was proven by 4 of our most advanced flyers at my field.

Both airplanes were on a 6V battery and they were both tested (after the crash) to be over 6V under load. Can someone explain what happened? You can imagine how skeptical I am over Hitec as I have had 2 unexplained servo failures on the same brand of servo and on the same surface, both doing significant damage to the airplane. I don't have an Escapade anymore since it was destroyed in the 3rd crash . Someone explain please... Here is the original thread I posted: http://www.rcgroups.com/forums/showthread.php?t=1853457
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Old Mar 18, 2013, 03:20 PM
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Joined Aug 2002
5,799 Posts
Quote:
Originally Posted by Rcflyyer1 View Post
Hi all, so last Sunday I was flying my Great Planes Escapade 40 which was fitted with my Hitec HS-485HB. The servo was not old at all. When I bought the servo, I believed that it should be sufficient to move a 40 sized sport airplane's elevator.
I have had 3 crashes, all the failure of elevator control and the 2nd and 3rd are blamed on the Hitec servo. On the 1st one, the clevis broke which ended up in no elevator control. The 2nd one was an elevator servo failure. I took off, did one circle in the pattern then lost the elevator on the downwind. Luckily, the grass was very soft that day and the plane wasn't totally destroyed so I repaired it.
The 2nd plane had a Hitec HS-311 which was determined to be the motor failure in the servo. The 3rd plane had a Hitec HS-485HB Deluxe servo. Again on the little 40 sized elevator. I fly it for a few months thinking everything is going well and it probably won't have any failures again but then suddenly, as I come in for a pass over the runway at about 15-20 feet in the air, suddenly I notice the nose pitching down, so I apply up elevator more and more and more until I am at the bottom of the stick. It wasn't signal loss since I still had aileron, rudder and throttle control. We tested all the servos after the crash and they all worked except for the elevator servo. The elevator servo would buzz when I tried to move it but wouldn't keep the arm still as I could move it in any direction I wanted to. Everything was plugged in too and we even plugged the bad servo into the throttle port and again, no control when we moved the throttle stick.
The crash into the runway totaled the airframe. The electronics are fine so I would really like Hitec to explain the loss of 2 airplanes with 2 of their servos having the same identical problem. My Futaba S3004 servos don't seem to fail on me, in fact I have been flying 10 year old futaba servos without any problem. A lot of the flyers up there were shocked and had changed views on Hitec.
We also have a lot of IMAA flyers with huge airplanes at my field and they were surprised to see a Hitec servo fail 2 times in the identical way. The servo failure was proven by 4 of our most advanced flyers at my field.
Both airplanes were on a 6V battery and they were both tested (after the crash) to be over 6V under load.
Can someone explain what happened? You can imagine how skeptical I am over Hitec as I have had 2 unexplained servo failures on the same brand of servo and on the same surface, both doing significant damage to the airplane.
I don't have an Escapade anymore since it was destroyed in the 3rd crash Someone explain please... Here is the original thread I posted: http://www.rcgroups.com/forums/showthread.php?t=1853457
. I was using a 6V 1700mah NiMh battery
Was this an AA size battery of a smaller sub AA or AAA?, minimum AA size required for a .40 size model.
Smaller NiMH simply can not handle the loads imposed on models larger than a .15.
Even an AA NiMH pack will hardly handle an HS-485HB under load as would then have been the case, from your other thread:
. Stalled Out.
also from your other thread:
. Just read your first post on the flutter of your elevator Flutter is the fastest way to destroy any model or servo.
. Flutter - Curing flutter by Ed Moorman
. Flutter - Cause, Cure & Misconceptions - with video.


Could go on at length but suggest best course is to email direct:
Hitec Warranty & Service - homepage.
Note: Hitec USA only services North/South America and Canada.
"Hitec USA customer service department is available Monday through Friday*
from 7am- 4:30 pm Pacific time. Reach us at 858.748.8440 or
service@hitecrcd.com any time you have a question"
If you are from a country that is outside North and South America, please contact the
Hitec distributor in your country for service.

Much more information available under sub sections
"Battery Care, Performance & DIY Battery Packs."
"Glitches & Jitter in Receiver, Servo & ESC - Causes and Cures"
"Servo - Alterations, Calculators, Databases, Leads, Repairs, Convert to an ESC or winch & FAQ."
below
"Radio Systems, Accessories, Alterations and FAQ" at
Alan's Hobby, Model & RC FAQ Web Links
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Old Mar 18, 2013, 03:59 PM
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Rcflyyer1's Avatar
United States, FL, Sarasota
Joined Dec 2010
331 Posts
Quote:
Originally Posted by A.T. View Post
. I was using a 6V 1700mah NiMh battery
Was this an AA size battery of a smaller sub AA or AAA?, minimum AA size required for a .40 size model.
Smaller NiMH simply can not handle the loads imposed on models larger than a .15.
Even an AA NiMH pack will hardly handle an HS-485HB under load as would then have been the case, from your other thread:
. Stalled Out.
also from your other thread:
. Just read your first post on the flutter of your elevator Flutter is the fastest way to destroy any model or servo.
. Flutter - Curing flutter by Ed Moorman
. Flutter - Cause, Cure & Misconceptions - with video.


Could go on at length but suggest best course is to email direct:
Hitec Warranty & Service - homepage.
Note: Hitec USA only services North/South America and Canada.
"Hitec USA customer service department is available Monday through Friday*
from 7am- 4:30 pm Pacific time. Reach us at 858.748.8440 or
service@hitecrcd.com any time you have a question"
If you are from a country that is outside North and South America, please contact the
Hitec distributor in your country for service.

Much more information available under sub sections
"Battery Care, Performance & DIY Battery Packs."
"Glitches & Jitter in Receiver, Servo & ESC - Causes and Cures"
"Servo - Alterations, Calculators, Databases, Leads, Repairs, Convert to an ESC or winch & FAQ."
below
"Radio Systems, Accessories, Alterations and FAQ" at
Alan's Hobby, Model & RC FAQ Web Links
It was an AA battery pack that I used on the model. I have also flown the model for a great amount of time with this battery pack without fault. This was the first flight of the day, but I will call or email Hitec about this. Thanks for the links
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