ASW-15 Spoiler Adjustment

Anyone have any experience tackling asymmetric dive-brakes on an ASW-15? The left side sticks up about 30mm more than the right side, and a mechanic and I spent the day fiddling with the adjustments (to no avail). We wrote Schleicher for the drawings, but does anyone have any insight?

Thanks.

Phil Chidekel

From memory, I believe both spoilers should go into over-center (one in each wing), if they is happening then the adjustment would be in the wing that has spoiler hanging open. Adjust the rod that goes between the over-center and the spoiler. I'd want to know why (how) it got so out of adjustment. Could have been an open spoiler hitting the side of the trailer as the wing is returned to the trailer.........look for bent pushrod.
Hope this helps,
JJ

On Wednesday, May 31, 2017 at 8:46:52 PM UTC-4, Phil Chidekel wrote:
Anyone have any experience tackling asymmetric dive-brakes on an ASW-15? The left side sticks up about 30mm more than the right side, and a mechanic and I spent the day fiddling with the adjustments (to no avail). We wrote Schleicher for the drawings, but does anyone have any insight?

Thanks.

Phil Chidekel

I have used the following process with good results:
1- With wings off, check that airbrakes close and lock correctly. When they go over center you will hear and feel a bit of a snap.
2- check for any binds or signs of interference that affect smooth operation. Also look for bad bearings or bent push rods.
3- Inspect the mechanism in the fuselage to verify that the two operating bell cranks for the brakes appear to be moving the same. Also verify that the mountings for these cranks are secure.
4- Assemble the glider.
5- Connect one airbrake push rod and lock brakes. Mark the position of the handle in the cockpit when it goes over center in the wing.
6- Disconnect first wing and repeat for second wing. This should give an indication which push rod needs adjusting. Lengthening make locking sooner. Depending upon handle position, shortening the rod on the brake that closes sooner may be the right action.
7 From recollection I believe both are supposed to lock within about 5mm.
Good hunting
UH

UH and JJ,

Thank you both for your responses.

There are two adjustments we have found: one is in the baggage compartment, and one is in the wing (accessible with the bottom spoiler removed).

The adjustment in the baggage compartment seems to be a "fine-tuning" of sorts--a way to calibrate the spoiler handle's position with the position of the pushrod. The adjustment in the wing seems to adjust the breakaway tension required to make the airbrake go over center. We have adjusted the breakaway tensions to be about equal--the brakes "pop" over-center within 5 pounds of tension of each other. This was the best we could do.

We tried lengthening the in-wing adjustment on the left (hanging out) side, and it didn't seem to change the timing of when the airbrake went over center; only the tension required. Is there another adjustment that we are missing? Or are we using what we have incorrectly.

We have checked for bent pushrods and the like... Apparently, this is a known issue on the -15. I'm almost sorry we opened the can of worms to begin with.

Thanks for your insight. Old gliders are cool--when they work.

Phil

On Thursday, June 1, 2017 at 7:38:58 AM UTC-4, wrote:
On Wednesday, May 31, 2017 at 8:46:52 PM UTC-4, Phil Chidekel wrote:
Anyone have any experience tackling asymmetric dive-brakes on an ASW-15? The left side sticks up about 30mm more than the right side, and a mechanic and I spent the day fiddling with the adjustments (to no avail). We wrote Schleicher for the drawings, but does anyone have any insight?

Thanks.

Phil Chidekel

I have used the following process with good results:
1- With wings off, check that airbrakes close and lock correctly. When they go over center you will hear and feel a bit of a snap.
2- check for any binds or signs of interference that affect smooth operation. Also look for bad bearings or bent push rods.
3- Inspect the mechanism in the fuselage to verify that the two operating bell cranks for the brakes appear to be moving the same. Also verify that the mountings for these cranks are secure.
4- Assemble the glider.
5- Connect one airbrake push rod and lock brakes. Mark the position of the handle in the cockpit when it goes over center in the wing.
6- Disconnect first wing and repeat for second wing. This should give an indication which push rod needs adjusting. Lengthening make locking sooner. Depending upon handle position, shortening the rod on the brake that closes sooner may be the right action.
7 From recollection I believe both are supposed to lock within about 5mm.
Good hunting
UH

Is the offending spoiler really hanging open 30mm...........that's a bunch, close to an inch! Did you mean 3mm? With a ship that has over-center mechanisms inside each wing, I would lock the spoiler in the bad wing and then adjust the link from the over-center to the spoiler. This rod has to effect the spoiler position. Take the bolt out and move the rod by hand to see what the spoiler does. When the spoilers in both wings are in over-center (closed & locked) and the spoiler caps are flush, put the wings back on the fuselage and adjust the rods inside the fuselage to where the Hotelier fitting easily snaps on the ball.
If one spoiler really is open 30mm.............something is bent, broken, loose somewhere.........find it before you fly it!
JJ

JJ,

The discrepancy is 9mm. Just re measured--I guess I'm a stupid American who needs to learn to speak metric.

I will fiddle with it some more.

Thanks.

Phil

Even 9mm is a lot, the DG-300 had a similar problem and it was found that the root rib was deforming under closing loads. Check the mounting of all spoiler controls.........looking for a loose rib or mounting pads, etc. Check the whole spoiler by trying to move it up-dowd, for-aft, Inboard-outboard to see if the pivot points are loose. Some sing very wong here!
JJ

Are you talking about the airbrakes in the closed position or the full open position? The only adjustment I've had to make to my 15B and another club member's 15 had to do with the airbrakes closed and locked position. In our cases one of the lower airbrake caps protruded slightly above the wing surface by about 3mm when closed and locked. In both cases adjusting the airbrake drive rod end in the wing by one half turn brought the caps flush with the wing surface just like the other ones. I experimented when doing mine and found that another half turn tighter or a turn looser and they wouldn't lock at all. We didn't need to disassemble anything to access and adjust this. We just slackened off the lock nut and removed the bolt that runs through the rod end so we could turn it as needed. The adjustment in the fuselage is is used to get both wings to lock at the same point - the manual says to check the point at which each wing locks individually and compare them. They should be within 5mm of each other. I expected that we would need to do this adjustment but the 15 checked at 4mm difference and my 15B (which had been about 2mm difference) was now less than 1mm. I checked multiple times because I had trouble believing things would work out so well. I've never thought to check how the left and right brakes compare when extended. Maybe I'll do that this weekend. My memory says that the control stop is in the fuselage and is in the part of the airbrake control system before the system splits to individual left/right subsystems.

Old gliders ARE cool when they work. Same goes for new gliders. I know a couple of people who paid a lot of money for new ships from well-respected German manufacturers and still had trouble. So far I've flown my old 15B over 800 hours and replacing the rudder cables is the most time consuming and troublesome thing I've had to do.