Straightened the Crooked Tail

I discovered a serious problem with my Bede BD-4C airplane as I was getting ready to install the top fuselage skin: the horizontal part of the tail was crooked. Specifically, the copilot’s side of the tail was about three inches higher (above the floor) than the pilot’s side. I did some careful measuring and figured out that the weldment that holds the horizontal stabilator was attached crooked to the end of the fuselage.

I rebuilt the gusset which forms the back of the fuselage, and one of the angles to which it attaches, reassembled everything, installed the tail, and found that the copilot’s side of the stabilator was still about 1.5 inches higher than the pilot’s side. I was thoroughly frustrated and completely flummoxed. By my measurements and calculations, the two ends of the stabilator should have been within 0.7 inches and the error was more than twice that amount. The shear amount of work involved in rebuilding the gusset again compounded my frustration.

This week, Steve from BedeCorp came to my “factory” to evaluate the problem and fix it. Many thanks to Jim Bede, Jr. for sending Steve. And many more thanks to Steve for figuring out what was wrong and actually getting it resolved!

Steve figured out that the weldment which attaches to the stabilator was sitting crooked on the plane. I had successfully fixed the problem that I had discovered; the weldment attached to the plane was straight. Here is a photo showing the problem. You can see the black weldment bolted to the fuselage; that one is straight. The curved weldment being held at an exaggerated angle holds the horizontal stabilator.

Bede BD-4C horizontal stabilator weldments
The weldment on fuselage is straight. The weldment that holds the horizontal stabilator is crooked.

With the weldment off of the plane, Steve determined that it has been incorrectly fabricated. There are two ears which hold the “hinge pin.” They should have been aligned and they were not. Here is a photo illustrating the situation. The hinge pin is a 3/8 inch rod running between the ears along the yellow line. Before the part was repaired, the ear in the red box was improperly attached so that the hinge pin ran along the green line instead of the yellow line.

Weldment with markings
The weldment had been incorrectly fabricated.

Steve cut the weld and removed the ear on the copilot’s side of the weldment. Under his direction, I built a jig to hold the weldment for repair. Steve then made a spacer so that the ear on the copilot’s side would be properly aligned with the one on the pilot’s side. A quick trip to S. S. Radiator & Welding Service in St. Peters got things fixed up properly. Here is a photo of the weldment, straight as it should be.

Bede BD-4C horizontal stabilator weldment
Stabilator weldment, repaired and straight

I have been grinning like a fool, now that this problem is fixed and I can finally make progress on my plane again. Pretty much everything I needed to do was blocked by what looked like the need to rebuild the tail end of the fuselage again.

I celebrated by bonding the top skin on the fuselage and attaching the vertical stabilizer.

Bede BD-4C with top fuselage skin and vertical stabilizer attached.
Bede BD-4C with top fuselage skin and vertical stabilizer attached.

If it seems like a long time since my last post, you’re right; it has been. I bonded the skins onto the bottom of the fuselage way back on April 7.

7 thoughts on “Straightened the Crooked Tail”

  1. what can be said art? Unfortunately the factory should have had a better quality control.I’m sure it was a big relief for you to see it was not your fault.!

  2. Sorry to hear that you had to chase a problem in their QC. Good to hear that they sent somebody down to fix it!

  3. I had in fact thought it seemed like a long time since the last post. I’m glad to learn things are straightened out.

    I confess until I read this post I had never come across the word “weldment” and had to look it up. (And my spell checker doesn’t know it either!) The things one learns from getting one’s hands dirty — or better yet, reading about friends getting their hands dirty!

    Good luck. May you soon have more progress to report.

  4. Like many others, I thought you were just taking a well needed pause. What if you had’t noticed the flaw? Did others leave the factory like that? Three cheers for the help they provided but it seems only fair.

  5. Art i’m glad you took it slow and did not bring a sledge hammer. I bet it was an immense relieve. Looks beautiful.

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