[Claude Parent]

I had a scary situation happen to me a few days ago in which my right side horizontal stabilizer broke off the tail boom and fell to the ground and has not been found yet.
I am attaching a few pictures of what I found still attached to the tail boom but the right side stab was gone and luckily fell off clear of the tail rotor.
My helicopter is an older Exec 90 converted to Jet Exec. I don't know how many total hours are on the helicopter. The failure happened after I completed a tail rotor balance and was doing a few circuits after the balancing. I looked at the building plans for the Exec 90, 162 and Talon and it looks like they are all the same as far as how the horizontal stab is built and attach the the tail boom. The drawings of all three versions show there's an outer and an inner tube and the inner tube is extended inside the outer tube and is attached with the two inboard, top and bottom rivets, the left side of the stabilizer has rivets that locks the inner and outer tubes together but the right side does not have these extra rivets. What happened to my ship is that metal fatigue got the best of the outside tube and broke but without the extra (inside the tail boom rivets) my right side stabilizer was free to tall right off the tail and luckily fell clear of the tail rotor. I am posting this as a PSA so this does not happen to anyone else. I will add this on my annual inspection list to check for cracks on the outside H stab at the first two inboard rivets. I have now added rivets to the right stab spar inside the tail boom so it is not possible for the stab to slide away should the outer tube fractures. I can't figure why the left side stab has rivets to lock the inner and outer tubes and the right side does not.
Any idea what happened here?


together but the right side does not ?????

[Lyle Swallows]

Wow! i am glad you escaped unscathed!
i just looked at my assembly since it is removed and i see the same issue you see, no cracks but no rivets or bolts to secure the inner spare on the inside of the tailboom. perhaps they didnt include any more rivets to make removal through the tailboom skin doubler easy without oblinging the hole? eitherway i'm going to install a bolt to secure the inside of mine and allow removal for future inspection.

i'm amazed no one has added a small angled bracket at the trailing edge to the 3rd bulkhead to alleviate any additional bending stress on the horizontal spar, i'm thinking like Robinsons have.

[Claude Parent]

Actually, someone did install a small support to the trailing edge of the hstab on his Rotorway, I saw a post on the Rotorway Owners Group showing the installation with pictures, here's a couple of pictures

[Sam Oliver]

Well.   That's disconcerting!  Did you notice it when it came off, or not until you were back on ground?

I'll go out later today and look at the stabilizers on my late model Talon Kit.  They are not yet installed so I can give them a good look see.   Spray a bunch of Anti-corrosion fluid down inside those tubes.

I wonder what caused somebody to put a brace on the trailing edge.

I'm no longer on Facebook (I just couldn't take it anymore), so if anybody sees any enlightening post over there, Please share it here as well.

I don't know if we have any aeronautical engineers on here, but I wonder if these stabilizers have a "flutter" issue.

[Claude Parent]

I had no idea the right stab was missing until I landed and walked around the heli, I was doing circuits at the airport so speed was relatively low. I am in the process of repairing and I want to try a small Gurney flap and the aft inboard angle bracket to support the back of the stab as pictured above in this post. I found the heli somewhat pitchy at higher speed so I will try the flap and see if it improves the handling. The balancing equipment is installed and it will be the first thing when I am flying again.

[Jared Hartzell]

Thank you for sharing this @Claude Parent , I had no idea this could happen (especially at low airspeed). While we regularly check the rivets every preflight to make sure they're not loose, this one is entirely new... Though it's difficult to tell from the pics, was the hole possibly not deburred/chamfered to prevent stress risers or cracks from propagating? I regularly fly at higher airspeeds than most and I haven't found it necessary to install a trailing edge support but it may not be a bad idea.