# Robinson Service Bulletin 72: No revision named - Rights: © Robinson. Filed by the FAA in regulations.gov docket FAA-2013-0159, the docket of AD 2014-23-16. Not covered by OpenAirDocs’ CC0 dedication. - Document: [Robinson Service Bulletin 72](https://openairdocs.org/service-documents/robinson/sb-72.md) - Title as filed: U.S. DOT/FAA - Robinson Service Bulletin SB-72 - Pages: 3 - PDF: https://openairdocs.org/files/sha256/e4/e4/e4e4a81e8fe1a9e11cc07c6b67606bf5f9e404a5f650f9b07d9610c4cfa6e645 - Page: https://openairdocs.org/service-documents/robinson/sb-72/file/e4e4a81e8fe1 ## 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) ROBINSON HELICOPTER COMPANY 2901 Airport Drive, Torrance, California 90505 Phone (310) 539-0508 Fax (310) 539-5198 Page 1 of 3 R44 SERVICE BULLETIN SB-72 DATE: 30 April 2010 TO: R44 and R44 II owners, operators, and maintenance personnel SUBJECT: Main Rotor Blade Bond Inspection ROTORCRAFT AFFECTED: R44 helicopters with C016-2 main rotor blades, and R44 II helicopters with C016-5 main rotor blades. TIME OF COMPLIANCE: At next 100-hour inspection, annual inspection, or by 31 July 2010, whichever occurs first, and at each 100-hour and annual inspection thereafter. BACKGROUND: Debonding of rotor blade skins can occur when the bond line is exposed due to erosion of the blade finish, or when corrosion occurs on the internal aluminum tip cap. Proper inspection and protection (refinishing) of bonded areas is required. Debonding resulting from improper inspection and maintenance could cause a catastrophic accident. COMPLIANCE PROCEDURE NOTE To facilitate inspection, blade may be teetered down, collective tully raised, and cyclic stick positioned to apply maximum up pitch. 1. Refer to Figures 1 and 2. Remove both main rotor blade tip covers and clean the blades. 2. Using 10x magnification, visually inspect uncovered skin-to-tip cap bond joints. Using a 1965-or-later United States quarter-dollar coin, tap test skin-to-tip cap bond joints on both upper and lower surfaces. If corrosion, separation, or voids are detected, blade is unairworthy. Tap test tutorial video is available at: www.robinsonheli.com/support.htm. 3. Using 10x magnification, visually inspect any exposed skin-to-spar bond line for gaps (empty space between skin and spar). Blade is unairworthy if any gap, including "pin hole(s)", is detected in the bond line. 4. Refer to Figure 2. Mark outboard 135 inches of blade lower surface as shown to identify skin-to-spar bond joint area. (OVER) ### Page 2 (OCR) R44 SB-72 Page 2 of 3 5. Verify no visible dents within the bond joint area. Blade is unairworthy if bond joint area is dented. 6. Tap test the lower skin-to-spar bond joint and verify no voids exist. Blade is unairworthy if a void is detected. 7. Refinish all exposed bare metal per R44 SL-32B. 8. Install blade tip covers, ensuring cover edges are flush with blade profile. 9. Make appropriate maintenance record entries. Approximate Cost: Parts: $5 for Kl-200 Kit if ordered by 31 July 2010. KI-200 Kit includes: 1 ea MT332-44 tool 1 ea SAN30001 Sharpie® marker Labor: Less than 1 man-hour. GAP in bond line requires blade replacement (example). PIN HOLE in bond line requires blade replacement (example). SKIN-TO-SPAR BOND LINE, located Bond Line (adhesive) 1.15 inch from leading edge of blade (requires inspection and evaluation if exposed, see text) EXPOSED SPAR METAL (example) REMOVABLE TIP COVER EXPOSED PAINT PRIMER (example) SKIN-TO-TIP CAP CRITICAL BOND JOINT 1.03 inches for P/N C016-2 - YELLOW PAINT 1.65 inches for P/N C016-5 MOO In MEN 1.37 inches for P/N C016-2 & C016-5 FIGURE 1. TIP AREAAND LOWER SURFACE (Example, Blade with Excessive Paint Erosion) ### Page 3 (OCR) R44 SB-72 Page 3 of 3 Hold MT332-44 (R44-series) tool against main rotor blade surface and leading edge while moving it spanwise. - 0.078-inch diameter Holes Marked Lines Insert felt tip of Sharpie® (brand) 30000-series "FINE POINT PERMANENT MARKER" thru holes in tool and mark two spanwise lines along lower surface from tip inboard 135 inches. FIGURE 2 MARKING LOWER SKIN-TO-SPAR BOND JOINT AREA THE DESIGN ENGINEERING ASPECTS OF THIS BULLETIN HAVE BEEN SHOWN TO COMPLY WITH APPLICABLE FEDERAL AVIATION REGULATIONS AND ARE FAA APPROVED. --- 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.