by Len Buffinton –
Fear not! Here are the basics of simple repair and maintenance of your Schempp-Hirth style air-brakes / spoilers.
If you have watched the video on “spoiler repair“, you have already learned how to take apart the spoiler and put it back together. This is simply a written, step by step recounting of the same information.
To begin, the spoiler needs to be in the extended position (sticking upward).
1) Grasp the top portion of the spoiler firmly, right at the pilot points. With a gentle, but firm motion, pull upward on this section. Use your other hand to control the “pop” off pressure when pulling on the spoilers.
Once the cap pops off the first pivot arm, repeat the process for the other pivot arm(s). Lay the cap aside, noting its original orientation. Make certain you understand how it comes off, mark the front and fuselage side with tape if necessary.
With the top portion off, you can clearly see the mechanism. Exercise the spoilers slowly as you watch how it all operates. If you are having an issue with the spoiler binding when it closes, you should be able to determine why at this point. If it operates perfectly, then the issue is probably with the spoiler cap binding in the opening when it closes, or catching on the second “plate” when it comes together.
2) Removing the second “plate” is simple, but be careful not to lose the little black “pins” that hold it all together. It’s a smart idea to place a white sheet or towel under the wing when working. Place your finger over the pin, and gently work the plate off the pivot arm being careful not to bend the plate. It may take a little wiggling, bit it will come right off. Place the little pivot “pin” aside. Repeat the process for the other(s).
Once again, you can move the mechanism back and forth to check for binding.
3) If you need to take more parts off, the pivot arms and slide mechanism are the only ones left. The outer pivot arms, the one(s) that are not attached to the slide mechanism, will pop off with FIRM pressure. You must first examine the way it attaches so you know which way to pop it off. Sometimes a flat blade screwdriver will help with this. To remove the pivot arm with the slide mechanism attached, you will need to undo the clevis inside the wing. Once that is accomplished, its pops off like the other one did. The slide mechanism is fitted into a slide channel on the end of the spoiler box, note which way it assembles.
All the parts, ready to be put back together again.
These are pretty simple devices, and there is not much that can go wrong. Usually, a little tweaking here and there will get them back to operating smoothly, however, every once and a while, you will notice the “pins” loosening up. When they do, that’s what causes the binding when the spoiler is retracted. The top and bottom plates are hitting. The pins should be pressed in all the way. If they continue to loosen up, a small drop of CA in the pin hole will help.
The last piece of advice I can offer is about the slide mechanism. If you study the way it operates, you see there is a small brass pin that sticks out from the pivot arm.
Spoiler slide, notice the "pin" that helps to pull open the blades
This pin has been known to break off. Also, if the pivot pin that holds the slide mechanism to the pivot arm loosens, the slide arm can “override” this brass pin, causing all sorts of binding. I have had this happen a few times in my HKM 28. The cure was to swap the two pivot arms (they are identical) and reassemble the mechanism but swapping the pivot arms.
As you have seen, these spoilers are fairly simple devices. With a little care and maintenance, they can work smooth and trouble free for a very long time.
