I fly an Aerobird which is the top of the line in the Firebird series from HobbyZone. It is a great plane, but there is a weakenss in the motor mount on all of these planes. Read my post, see what happend to me and what you can do to prevent this from happening to your "bird".

Last week I took a good shot in a rough landing and the motor broke free of its mounting and shifted forward inside the plane. I have since learned that this is not uncommon. Also, while mine was dramatic, if it is only a small displacement, you might not notice it, but the motor can get out of the proper thrust line.

After some experimentation and excellent advice from other threads, I have begun to rebuild the Aerobird and repair the damage done by the forward shifted motor. A tip on how to prevent this on your plane is at the end.

Here is what I did.

Several people who had had this same problem put various types of plates behind the motor inside the body. Then I recalled seeing someone drill holes from the sides, right behind the motor and put a tie wrap there. This holds the body tight to the motor AND blocks it from shifting backward. That is what I did as part of my repair. The holes are 1/2" apart centered on the motor. I used an 8" tie wrap, but a 4-6" wrap would probably be better as they are a little less bulky.

Here are pictures of the damage and the repair.
http://www.shutterfly.com/osi.jsp?i...e21b33868c5a42d

The photos show a yellow tie wrap, but that was just for pictures. I cut this out and replace it with an orange one that looks much better on the plane.

After putting this tie wrap in place, there was no longer a need to put any kind of bracing plate by the prop area. This tie wrap really holds the motor solidly AND prevents it from moving forward.

Recommendation to all Firebird, Firebird XL, Fighterbird and Aerobird flyers and those with similar fuselage planes:

I love the Aerobird and think the whole "bird" series is fine. However a weak motor mount exists in all the planes. One good crash and the motor gets out of alignment, or breaks free, like mine. I would recommend this modification be done on ALL new "birds" BEFORE the motor mount is challenged and repairs have to be done. If the motor shifts far enough, it will hit the control board and wipe out all of the electronics. If it only shifts a little, the plane flies badly, commonly to the left or right and can't be trimmed properly.

You can do the drilling and insertion of the tie wrap without having to take the guts out of the plane. Just be careful to limit how far the drill bit goes inside the plane. There is enough room to do this, just be careful.

When you put the tie wrap in, it may have to slip under the noise suppression components that are soldered between the motor terminals. You can see them in the photo. A 4" tie wrap is not as wide as the 8" wrap I used, so it will fit more easily with less displacement of the components however I am confident that it will be strong enough to get the job done.

To avoid the electronics on the motor, you could shift the holes about 1/4 inch away from this part of the motor so you don't have to go below the components. Either way, just take your time and don't over tighten the tie wrap. Just make it snug, don't distort the body of the plane.

I plan to send a note to the manufacturer and advise that this should be done at the factory.

I hope you find this post and the photos useful. Thanks to everyone for their advice and tips.

Don't wait, do this mod now on your Firebird, XL, Fighterbird or your Aerobird, before you need it![img]i/expressions/face-icon-small-cool.gif[/img]