# Schweizer Service Bulletin C1B-032: No revision named - Rights: © Schweizer. Filed by the FAA in regulations.gov docket FAA-2011-0593, the docket of AD 2011-12-16. Not covered by OpenAirDocs’ CC0 dedication. - Document: [Schweizer Service Bulletin C1B-032](https://openairdocs.org/service-documents/schweizer/c1b-032.md) - Title as filed: U.S. DOT/FAA - Schweizer SB C1B-032 - Pages: 4 - PDF: https://openairdocs.org/files/sha256/c8/9d/c89de373831f275d1bb99a8c9f79eed352ba6f40623ecbf60822c936e72bf14d - Page: https://openairdocs.org/service-documents/schweizer/c1b-032/file/c89de373831f ## 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) C1B-032 SCHWEIZER 21 Dec 2010 CHWEIZER SERVICE 269 SERIES BULLETIN MANDATORY MANDATORY MANDATORY SUBJECT: INSPECTION AND MODIFICATION OF TAILBOOM SUPPORT STRUT EXPANDABLE BOLT MODELS AFFECTED: • Model 269C-1 helicopter with serial No. 0156 and subsequent. • All Model 269C-1 helicopters with Aft Cluster Fitting Modification Kit SA-269K-106 installed. TIME OF COMPLIANCE: Part 1: Prior to next flight. Part 2: Within next ten flight hours. REFERENCE: Schweizer S-300CB, Model 269C-1 Helicopter Basic HMI PREFACE: Schweizer Aircraft received a report that a tailboom support strut expandable bolt came loose and departed the helicopter. An investigation concluded that the locknut holding the expandable bolt in place worked loose during flight. • This service bulletin contains two parts: • Part I requires the operator to immediately verify that there is sufficient drag torque on the left-hand and right-hand locknuts, and that both locknuts are properly torqued. • Part II provides instructions to modify both expandable bolts to allow the addition of a secondary safety mechanism. • Both parts of this service bulletin must be complied with. WARNING FAILURE TO COMPLY WITH THIS SERVICE BULLETIN MAY LEAD TO LOSS OF CONTROL OF THE HELICOPTER AND SUBSEQUENT INJURY, DEATH AND/OR PROPERTY DAMAGE. FAA APPROVAL: The technical aspects of this Service Bulletin are FAA approved. PARTS REQUIRED: MS24665-132 Cotter Pin (Alternate MS24665-151) - 2 req'd . Page 1 of 4 S-240 SCHWEIZER AIRCRAFT CORP. 1250 Schweizer Road Horseheads, NY 14845 ### Page 2 (OCR) C1B-032 21 Dec 2010 PROCEDURE: NOTE There are two aft cluster fittings, each with an expandable bolt. The following procedure is to be performed at each location. PART I: a. See Figure C1B-032-1 and note locations of aft cluster fittings and expandable bolts. b. Loosen MS21043-3 locknut and verify drag torque of at least 2 in-lbs. Verify locknut cannot be rotated on bolt using only finger pressure. 1. If sufficient drag torque has been verified, re-torque locknut to 23 in-Ibs. 2. If locknut does not have sufficient drag torque, remove and discard locknut. Replace with new MS21043-3 locknut. Torque locknut to 23 in-Ibs. c. Record compliance with Part I of this service bulletin in the helicopter records. PART II: a. Remove ADB221-1A expandable bolt from helicopter. b. Modify expandable bolt as follows: 1. Remove washers and bushings from bolt. Retain all parts. 2. Secure bolt in drill vise. 3. Using a drill press, drill 0.070-0.080-inch diameter hole through threaded portion of bolt, centered 0.083-0.093-inch from end of bolt. 4. Chase threads of bolt to remove any burrs. CAUTION It is critical that the correct expandable bolt hardware stackup be achieved. c. Reassemble washer and bushings onto bolt per appropriate HMI, Section 11. d. Install expandable bolt per appropriate HMI, Section 11. e. Install washer and MS21043-3 locknut on bolt. Verify drag torque of at least 2 in-Ibs. Verify locknut cannot be rotated on bolt using only finger pressure. If locknut does not have sufficient drag torque, remove and discard locknut. Replace with new MS21043-3 locknut. Page 2 of 4 ### Page 3 (OCR) C1B-032 21 Dec 2010 f. Torque MS21043-3 locknut to 23 in-Ibs. g. Install MS24665-132 or MS24665-151 cotter pin on expandable bolt. h. Record compliance with Part Il of this service bulletin in the helicopter records. WEIGHT AND BALANCE Weight and Balance are not affected. Page 3 of 4 ### Page 4 (OCR) C1B-032 21 Dec 2010 TAILBOOM CENTER ATTACHMENT FITTING LOCKNUT, WASHER (TORQUE LOCKNUT TO 23 IN. LBS, INSTALL COTTER PIN) TAILBOOM AFT SUPPORT CLUSTER STRUT FITTING ADB221-1A EXPANDABLE BOLT (DETAIL A) STRUT INSTALLATION WHEN 269A2234-5 / 269A2235-5 AFT CLUSTER FITTINGS OR KIT SA-269K-106 IS INSTALLED TYPICAL LEFT SIDE AND RIGHT SIDE DRILL 0.070-0.080 INCH DIA. HOLE 0.083-0.093 DETAIL A Figure C1B-032-1. Tailboom Support Strut Expandable Bolt Inspection and Modification Page 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.