Main Gear: The 4 AN4 bolts that hold the axle failed in tension. The wheel was found off in the brush but the tire, wheel, brakes and axle were undamaged. The airplane slid for 290' on the left strut minus axle. This ground it down about 2" to the mid point of the axle bolt pattern. Examination of the attach tabs indicated that the right one was fine but the left one was delaminated from the gear hoop. I built a simple puller to remove the studs from the attach tabs and removed the gear. This was pretty easy. The top part of the attach tab was fine only the bottom (45 plies) were debonded. Both studs were bent, the right one just a little. Once the gear was out. I found that the bending of the left stud and the MKMGA sleeve had crushed the tab around the lower part of the rear hole. The upper part of the hole was fine. I pulled off the lower 45 ply part of the tab (both front and rear part of the tab) and ground out the chrushed uni. I was able to insert the new MKMGA into the existing hole and fill the crushed foam area inside between the tabs around the MKMGA with flox. I let that cure and removed the MKMGA, leaving a hole exactly where the MKMGA used to be. A little of the uni from the upper 45 ply layer was missing also. I built up the inside part with uni which was layed in vertically and rests ontop of the remaining uni that runs on top ot the gear hoop (45 ply upper laminate). Then I layed up a 45 ply layer on the rear tab around the bottom of the hoop to near the mid point. Once this was cured, I re-drilled the hole for the MKMGA using the hole in the flox as a guide for my spot face. I put a 1/4" drill bit in the spot face hole to re-drill the pilot hole, then drilled the 5/8" hole with the spot face. Then I layed up the 45 plies on the forward tab and used the spot face simularly from the rear hole to re-dril the forward hole. I then floxed the MKMGA back in the hole keeping the exposed part of the MKMGA the same as it was before I removed it. I then reinforce the bid over the MKMGA between the studs. I was very fearful that after re-drilling both holes for the MKMGA that the gear would not fit in the fuselage. However, it went right in with a few taps with a hammer on a wooden block and a nut on the studs.
On the lower gear leg, I measured the thickness of the strut. I then ground the outside of the strut away so that it was half it's thickness at the bottom. This tappered to full thickness at a point 8" up the strut. I built a form out of thin aluminum to contain the uni I would lay back in. This went along the extended inside surface of the grear leg. I filled foam in below the end of the strut about 3" the same thickness as the remaining strut (1/2 the original). I covered this with duct tape. I then cut 96 S-glass uni strips varying in length from 6" to 11". I layed these in to the form with the lower ends all 3" below the remaining strut and the other end tappering up to a point 11" up or 8" up from the remaining end. After this cured, I removed the form and the foam. I drilled the 2 axle attach holes just where they had been before. I then ground a tapper on the inside just as I did on the outside. The original gear material was in the shape of a chisle point. I glued a form on to contain the uni and then I laid up the innner 96 plies simularly as the outside. Once cured I ground this to the same shape as the original strut. I drilled the four attach holes back thru the inner part of the strut using the 2 holes that were there and the axle base as a guide. At this point I layed the gear down horizontal (this is prior to the tab repair above) and used a digital level to make the MKMGA's level with each other. I temporarily mounted the axle to check the toe in. I ground the uni until it was right. Then I layed up the torsional uni layers per plans starting about 2" above the uni added. I put safety wire thru to mark the four attach holes and after cure drilled the holes thru the torsional layers. I then cut out the gear leg to fit the matco brakes and mounted the axle using flox to make a final adjustment to the toe in. |
