J-P

My Feedback: (1)

Hi BAX

On the 16 of june I sent an e-mail to [email protected] for a gear failure on 2 brand news BLS 651 servos.

Have no reply to date.

Any information available?

Thanks,

Jean-Paul

Krysta

We are sorry, we have hunted through our email to Support and cannot find any from you. It may be a filter problem on our end, we are not sure.

You can either resend your inquiry, or you can ask your question here in the forum.


Sincerely,
Krysta
Product Development & Support Specialist
Futaba Service Center USA
[email protected]

J-P

My Feedback: (1)

Thanks Krysta
Send you again my e-mail
Jean-Paul

J-P

My Feedback: (1)

Hi BAX

I sent you 2 e-mails to [email protected], and [email protected], but don't have any answer.
So I post here my question:


When installing the servos on my new F3A pattern plane, I used the aluminium Futaba arms.

I don't know what happened, didn't had the feeling to overtight the furnished servo screw, but the next day, when unscrewing the arm to adjust the control length, I found the main gear broken.

Same thing happened on the other elevator BLS 651 servo .....

I was expecting it to be of metal, or strong plastic....

Instead it was like sand, breaking in pieces.

I have two other similar servos, and 2 BLS 153 with similar gear, so I'm a little bit scared about using these servos.

Did you had already similar defects reported, and what do you recommend?

__________________________________________________ __________

This was the first e-mail I sent you..

Second part

Without any answer from FUTABA, I decided to fly my brand new plane with two news BLS 651 I had.

Five days later after maybe 50 flights, when checking the plane before traveling to the National Championship, I found another BLS 651 FUTABA Gear broken......

My preflight saved me a 6000$ plane.....


I bought 2 BLS 651 at Graves Hobby Shop in Orlando, 2 at WAIGO in HongKong and 2 in France ........

On the one broken on the plane after 50 flights, I had just lightly tightened the screw...

So maybe the aluminium Futaba arm is the problem, or a bad series of gear......

Now I'm sitting in front of 3 broken servos, and have to wait for replacement parts, not available ....

During the French Championship, one of the Team Member reported a similar problem, and we were told somebody lost half a stab in flight, after an elevator failure during a contest.

So again my question :

Did you had already similar defects reported, and what do you recommend

Bax

My Feedback: (11)

Are those the stock screws that came with the servo, or other screws? Did you use any kind of thread-locking compound? We cannot tell much from the photographs.

J-P

My Feedback: (1)

Stock screws were used as you can see on the pics, no thread-locking compound.

After replacing the servos gear , I just gently tightened the screws, ..... Futaba stock screws, ...no Loctite or Zap, no stress was put on the control arm or the gear.


I received a few e-mails..... and it seems it already happened ... on both sides of the Ocean !

Here is an attempt of explanation I received last night :


" I had a similar problem with steel Bolts used on our - . We were getting them made in China. The heads of the bolts would fall off a day or two after we tightened them. The problem turned out to be a combination of poor steel, hydrogen embrittlement, and improper heat treating. I don't know what these gears are but it is quite possibly the same sort of thing. It looks like stress builds up in the gear and it is cracking. These are probably sintered parts so it may mean that they have poor heat treating as well. A sintered part is made from powdered metal. The powder is put into the mold and is melted and cooled. If they don't melt it properly it will not have strength and will be powder. If they don't heat treat it then it will have no strength and will break apart as well. I was thinking about this when you sent your earlier emails and now, with the report of more troubles then I think it is a manufacturing problem. Controlling metal parts made in - is a challenge. "


So it could be just a bad gears batch ......

If you have a few sets of gears your are confident in, I'll replace mine, and repair the other servos.

I had no problem in flight with the BLS 651, and it looks to be accurate.

Jean-Paul

Bax

My Feedback: (11)

Please be advised that we are the service and support center for Futaba in North America. We are not part of Futaba Corporation. You will have to contact the service center in your country for warranty assistance. For France:

Aviomodelli France
Z. I. Sud
84101 Orange Cedex
Telephone: +33 490-34-5906
Fax: +33 490-34-9410

J-P

My Feedback: (1)

I'm a little bit surprised to read your answer.

It don't help to know what happened with these gears.

Two of the broken servos come straight from Graves Hobby Shop in ORLANDO where I spend the winter.....

So I'm waiting a different answer.

Regards,

Jean-Paul

Bax

My Feedback: (11)

OK, we erred. Servos bought in the U.S. can be serviced by us. We'd not know why the output shafts are breaking unless they are being subjected to high loads. Flutter can cause problems, too, even if it's not severe enough to damage the control surface or the hinges.

If you wish to have the servos covered under the warranty, they need to be sent to us per the note in the thread at the top of this forum. We'd also like to see the servo arms and the screws used to hold them onto the servo.

J-P

My Feedback: (1)

Thanks for your last answer Bax

The only thing it could be interesting to know is why the output gear is breaking, and to advise people to check by unscrewing the servo arm if there is a potential crack in the gear.

I'll be in Muncie for the WC, arriving the 18 of july in Chicago and can show you the servos if you plan to attend at the WC, or send you the broken gears.

You will notice that you can break them in pieces with two fingers.

The screws used were the stock ones coming with the servo, and the arms are the blue aluminium Futaba ones.

These servos are new, two never flew, and on the one broken after 50 flights, I never experienced any kind of flutter.

I don't ask to have these servos exchanged. I just want some output gears of a different batch, because I think it's the problem, and I will replace them.

At this time they are out of stock at Tower Hobbies, but I'm ok to pay for these gears, must just cost a few dollars....

I can understand than this can happen, and it don't change my opinion about these servos I want to keep on flying with.

I hope my feedback will permit other guys to prevent an inflight failure.

Checking the slope on the elevators during my preflight check saved my stab, and maybe my plane...

Jean-Paul

J-P

My Feedback: (1)

Two other pics you can identify on the screws and Futaba arms.

Dre

My Feedback: (2)

J-P,

Yours is not an isolated incident. I had the same thing happen to me. The servo was being used on elevator halves in a pattern airplane and the spline gear on one servo sheared off during a snap - within a few flights of first use. Fortunately, I still had one elevator half and was able to land safely.

Non-metal servo arms were being used, the screw was factory and not over-tightened, and no thread locker was used.

Upon inspection I found the 651 spline gear to be very brittle relative to the ones made from the white nylon? that we normally see in servos (e.g., 9650). Tap the different gears on a glass table and the brittleness will be obvious from the sound.

Basis my experience and observations I will not use this servo.

Andre Bouchard

J-P

My Feedback: (1)

Hi M. Baxter

Did you found why these gears are breaking ?


Jean-Paul

Bax

My Feedback: (11)

Problems with that particular servo are actually quite rare. We'd have to see specifics to even have any idea why some might be failing. It's certainly not a common difficulty.