# Grob Service Bulletin TM 306-29: No revision named - Rights: © Grob. Filed by the FAA in regulations.gov docket FAA-2007-28435; AD 2011-01-03 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. - Document: [Grob Service Bulletin TM 306-29](https://openairdocs.org/service-documents/grob/tm306-29.md) - Title as filed: U.S. DOT/FAA - Service Bulletin - Pages: 4 - PDF: https://openairdocs.org/files/sha256/a1/f0/a1f097addd907eed11deb33be59e0df533f2a893e2c9cf539082e7733abf9a29 - Page: https://openairdocs.org/service-documents/grob/tm306-29/file/a1f097addd90 ## Text This text is OCR from a scan. OCR can misread letters and numbers. Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 (OCR) Service Bulletin GROB TM 306-29 ASTIR CS GROB- TM 320-5 SPEED ASTIR II LUFT UND RAUMFAHRT Subject: Inspection and replacement of spar spigot assemblies Concerning: Model: ASTIR CS TCDS No.: 306 - Series: - S/N: ASTIR CS 1001-1536 ASTIR CS 77 1601-1844 ASTIR CS Jeans 2001-2248 CLUB ASTIR II 5001-5061 (Suffix "C") STANDARD ASTIR II 5001-5061 (Suffix "S") G 102 CLUB ASTIR III 5501 & up (Suffix "C") G 102 CLUB ASTIR IIIb 5501 & up (Suffix "Cb") G 102 STANDARD ASTIR III 5502 & up (Suffix "S") Model: SPEED ASTIR II TCDS No.: 320 - Series: - S/N: SPEED ASTIR II 4001-4027 SPEED ASTIR IIB 4028-4107 Urgency: See Actions Procedure: As a result of the replacement action of the G 103 TWIN ASTIR spar spigot assemblies, the Gliding Fede- ration of Australia issued a directive to inspect the similar main spigots of single-seater sailplanes. Because the reports of ostensibly discovered cracks are increasing, GROB has decided to issue this Ser- vice Bulletin as a pure precautionary measure. Actions: The following actions are to be taken: 1. Inspection of the main spigot assembly Before the next flight, inspect both spar spigot assemblies for cracks using a suitable procedure (magnifying glass with a minimum 10 times magnifi- cation, dye penetrant, magnetic particle). Important: When carrying out the crack inspection, ensure that any gap between the spigot plates and the spigot is not interpreted If no crack is discovered and if the distance bet- ween spigot plates and swivel bearing is (refer to figure on page 3): • b ≤ 10 mm: Carry out Action 2 not later than 31 December 1992 • b > 10 mm: Carry out Action 2 not later than 30 June 1991 12.07.1991 ENS 10A 1001990 COTION BEARSEITET PREPARED B . Altmanr MUSTERGEPRUFT / APPROVED BY SEITE / PAGE 1 of 4 ### Page 2 (OCR) Service Bulletin GROB TM 306-29 ASTIR CS • GROB- TM 320-5 SPEED ASTIR II LUFT- UND RAUMFAHAT If a crack is discovered and if the distance between spigot plates and swivel bearing is b ≤ 10 mm, the crack may initially be blended out (refer to page 4 for procedure): * Removal of crack is possible: Warning: After blending, check that dimension Carry out Action 2 not later than 31 December 1992 b is still ≤ 10 mm. • Removal of crack not possible: Carry out Action 2 immediately If a crack is discovered and if the distance between spigot plates and swivel bearing is b › 10 mm, Action 2 must be carried out immediately. 2. Replacement of the spar spigot assembly Replace the spar spigot assembly in accordance with Installation Instruction No. 306-29/320-5. The modifications must be performed in conformance with the follow- ing drawings: New Drawing Replacement for Drawing No. Issued | Title Drawing No. Issued Title 102-1909/1910|30.08.1990| SPIGOT ASSY 102-1012/1013 |15.02.1975| SPIGOT ASSY | LH / RH 102C3-1012/1013|26.11.1980| RH/LH 104-1909/1910|30.08.1990|SPIGOT ASSY 104-1003/1004 |20.09.1979| SPIGOT ASSY ILH/RH 104-1012/1013 |30.05.1978|RH/LH Weight and Ene y weallation of the of g. have to be determined after Balance: new spar spigot assemblies. Remarks: Action 1 can be carried out by a competent person who is versed in the operation of the inspection methods and has to be certified in the logbook. Action 2 may only be carried out by an aviation workshop with authorization for GRP repairs. The proper execution has to be certified in the logbook by an authorized inspector. Mattsies, 11 October 1990 LBA approved: 0 5. Dez. 1990 Dipl. Ing. J. Altmann (Airworthiness engineer Certification staff) Approval of translation has been done by best knowledge and judgement. -In any case the original text in German language is autoritive.- Note: If in the meantime you have sold your glider, we would that you kindly pass this information immediately to the new owner and forward his address and aircraft s/n to us. ERSETZT AUSGABE / ISSUE EDITION BEARBEITET / PREPARED BY MUSTERGEPRÜFT / APPROVED BY 11.10.1990 J. Altmann ### Page 3 (OCR) Service Bulletin GROB TM 306-29 ASTIR CS GROB- TM 320-5 SPEED ASTIR II LUFT- UND RAUMFAHRT Definition of the distance b DATUM / DATE ERSETZT AUSGABE / ISSUE EDITION BEARBEITET / PREPARED BY MUSTERGEPRÜFT / APPROVED BY SEITE / PAGE 11.10.1990 J. Altmann 3 of 4 ### Page 4 (OCR) Service Bulletin GROB GROB- TM 306-29 ASTIR CS LUFT- UND RAUMFARRT TM 320-5 SPEED ASTIR II Comments to crack inspection max. 5 mm deep To perform the crack inspection the section of the wrapping around the main spigot has to be removed (max. 15 mm) and the adhesive material removed to expose the welding seam (max. 5 mm deep, see figure). Be very careful not to scratch or otherwise damage the spigot or plate. If the weld seam is continuous around the plate, the complete toe of the welding seam has to be inspected. Grooves or nicks in the surface of the welding seam which are not part of a crack must be polished out and the crack inspection performed again. Procedure for blending out a crack A crack may be blended out if the following conditions are fulfilled: * crack on one side not deeper than 0.75 mm polished * cracks on both sides not deeper than 0.5 mm each Blending out should be done with grinding caps or equivalent. The grinded surface has to be polished. Sketch mentioned below shows a cross section of blending out a crack. SPIGOT PLATE CrACk SPIGOT Finally apply a coating of resin to the exposed area (wood and metal). DATUM / DATE ERSETZT AUSGABE / ISSUE EDITION BEARBEITET / PREPARED BY MUSTERE APPROVED BY SEITE / PAGE 19.12.1990 11.10.1990 J. Altmann 4 of 4 --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain, except the copies of manufacturers’ service documents, which belong to their rights holders.