pdf Gfa ad 370 issue 2 Popular

INSPECTION AND POSSIBLE REPLACEMENT OF THE WING MAIN SPAR, ROOT END STUB FITTINGS 

Applicable to all Grob single seat gliders, all numbers and all models. Grob Twin Astir gliders, worldwide, have been subjected to the inspection and replacement of their wing root, spar stub end fittings (refer G.F.A. AD 346). In Australia this uncovered 5 out of 18 gliders with cracked pins, the last one having less than 120 hours total flight time. The cracks are considered to be the result of poor welding and manufacturing techniques. The British CAA has issued AD 006-10-88 which asks for inspection of the pins for cracking at the toe of the fillet welds on the stub end fittings on all Grob G109 series powered sailplanes. The above events make it impossible to ignore the probability that single seat Astir stub end fitting spigots may have some manufacturing induced cracking at the welds joining the vertical plates to the pins. This was confirmed when Australian single Astirs inspected to AD 370 Issue 1 indicated that a large percentage were cracked. Resulting from the above, Grob have issued LBA approved Service Bulletins TM 306-29/TM 320-5 detailing the Inspection and/or Replacement requirements for the stub end fitting spigots fitted to the single Astir series sailplanes. The new requirements introduced in AD 370 Issue 2 replace and supersede those previously given in Issue 1 of this AD. Issue 2 also provides the terms for continued service for those single Astir found crack free on their initial inspection. The following LBA approved Grob Service Bulletins TM 306-29 and TM 320-5 form part of this AD including the APPENDIX A: Spigot Magnetic Particle inspection procedure.