On Friday, August 23, 2013 12:33:01 PM UTC-7, wrote:
On Thursday, August 22, 2013 7:45:37 PM UTC-4, Eric Greenwell wrote:

wrote, On 8/22/2013 1:47 PM: Hi, I'm considering buying an ASH26 which has had a major wing repair. If there are any owners here I would be very grateful if they could share the frequencies quoted in their delivery documentation It might be more valuable to have them show you the pictures and videos of the proof loading tests done after the repair. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) - "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm http://tinyurl.com/yb3xywl



If the repair has been done iaw the manufacturer's repair instructions there should be no reason to do any test loading of the repaired part. I have heard of this being done only once and, if I recall correctly, it was JJ after he did a wing root rebuild with spar splice on his Genesis.

FWIW

UH

The problem with doing a spar cap repair is none of the manufactures repair manuals deal with it, Schleicher only mentions that cap repairs at the wing tip should be 100 to 1 and at the root 400 to 1. I wrote to one of Genesis-2 design team members and got his OK to go ahead with my repair scheme. The prior owner of my ship tried to land on a county road and caught the left wing tip on a steel fence post. That ground looped him head-long into the fence at touch-down speed! The next post penetrated the D-tube back to the spar right in front of a 5" inspection hole located behind the spar. The wing flexed back, the carbon spar snapped and 5 feet of the left wing tip, fell to the ground.

As the left wing tip was being severed, the cockpit was slamming into the barbed-wires! All 4 strands broke through the canopy, ripped the compass off the top of the instrument panel and then hit the pilot in the face! His life was saved because the fuselage was going down into the road-side ditch as the wires ripped through the cockpit and rode up and over his face! Need I say that county roads make a poor choice for a landing?

The ship was out of production and no replacement wing was available. The insurance company 'totaled' the ship and put it up for salvage bid. The spar repair was complicated because the caps are made from grouping 1/8" carbon rods with over 100 at the root and 26 at the tip. Spar taper is achieved by dropping a carbon rod every 3", or so. I decided on 200 to 1 and removed the outer skin some 5' inboard which made the scarf start just outboard of the wing tank (thank God). Using a carbide disk in my hand saw. I set the depth to 1/8" and removed the first row of carbon rods. Then (moving outboard) I set the depth to 1/4" and removed the second layer........then 3/8", etc.

I set the gig on my 25' level table using the good right wing with a saddle at the root, tip and near the break. Saddles were made for both sides of the 'good' wing. Reverse the saddles and lay in the parts to set up the top spar cap repair on the broken wing. Replacement rods were run as long as possible, remembering the 'drop a rod' every 3" must continue in the repair area and the rod bundle must be wrapped in a cloth bundle. With the wing perfectly aligned, we laid in something like 50 rods, all wet out and set in flox mixture, wrapped in 92110 fiberglass cloth. I covered this with aluminum wrap and set a 2X4 on top with lead weights to keep things in place. As much wing skin was replaced as could be accomplished from top side then we
carefully raised the wing and laid it upside down using the other side wing saddles.

OK, the wing is back together and straight, but is it as strong as it once was? I asked Stan Hall (RIP) and he told me there is only one way to know for certain. TEST IT. The wing in flight carries its own weight and sees as a load only the fuselage with everything in it, mainly the pilot. That is the weight I used X 5.3 G's. The wing was assembled upside down on saw-horses and some 2600# of sand was laid on, two bags at a time working both wings together.

Now I know my wing repair is strong enough, because I have tested it to the maximum stress it should ever see (if the ship is flown within manufactures limits)
JJ