# Bell Alert Service Bulletin 412CF-13-52: No revision named - Rights: © Bell Textron Inc. Filed by the FAA in regulations.gov docket FAA-2013-0639; AD 2013-15-02 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. - Document: [Bell Alert Service Bulletin 412CF-13-52](https://openairdocs.org/service-documents/bell/412cf-13-52.md) - Title as filed: U.S. DOT/FAA - Bell ASB No. 412CF-13-52 IR dated 2-04-13 - TR Blades - Pages: 4 - PDF: https://openairdocs.org/files/sha256/13/e0/13e08b28a0702443c3e3889bf91764a54e17de8efad2125f56240550d24fab13 - Page: https://openairdocs.org/service-documents/bell/412cf-13-52/file/13e08b28a070 ## Text Each page's text from the PDF; open the PDF at a page with #page=N. ### Page 1 ASB 412-CF-13-52 Page 1 of 4 ECCN EAR99 ALERT SERVICE BULLETIN 412CF-13-52 4 February 2013 MODEL AFFECTED: 412CF SUBJECT: TAIL ROTOR BL ADE P/N 212-010-750-ALL, INSPECTION OF HELICOPTERS AFFECTED: Seri al number 46400 through 46499. COMPLIANCE: Within the next 25 hours and every 25 hours thereafter DESCRIPTION: Bell Helicopter has recently examined a fractured tail rotor blade; the fracture originated from surface damage. This ASB introduces a 3X magnifying glass inspection of the tail rotor blade surface for damage every 25 hours. Any damage is to be investigated by removing paint an d inspecting skin condition with 10X magnification. Due to the crit ical nature of this inspection and requirements to fully comply, Bell Helicopter is adding a local in spection with 10X magn ification of blade between stations 20.00 to 35.00 from the leading edge to t he trailing edge. This is in addition to the 3X requirement for the full blade. Operator s are reminded that it is critical to investigate any paint and skin imperfections should the inspection warrant. If anomalies are noted during the 3X/10X inspec tions of the blade surface, remove the paint and check skin condition again with 10X magnification. Skin damage exceeding Maintenance Manual limits requires blade remova l from service. Applicability of this bulletin to any spare part sha ll be determined prior to its in stallation on an affected helicopter. APPROVAL: The engineering design aspects of this bulletin are FAA/ODA approved. ### Page 2 ASB 412-CF-13-52 Page 2 of 4 ECCN EAR99 CONTACT INFO: For any questions regarding this bulletin, please contact: Bell Helicopter Product Support Engineering - Medium Helicopters Tel: 450-437-6201 / 1-800-363-8028 / psemedium@bh.com MANPOWER: Approximately 1.0 man-hour is required to complete this bul letin. This estimate is based on hands-on time, and may vary with personnel and facilities available. WARRANTY: There is no warranty credit applicable for parts or labor associated with this bulletin. MATERIAL: Required Material: The following material may be required for the accomplishment of this bulletin and may be obtained through your Bell Helicopter Textron Supply Center. Part Number Nomenclature Qty 212-010-750-133 Bl ade A/R Consumable Material: The following material may be required to accomplish this bulletin, but may not require ordering, depending on the operator’s consumable material stock levels. This material may be obtained through your Bell Helicopter Textron Supply Center. Part Number Nomenclature Qty Reference * P-C-451 Abrasive Cloth or Paper, Aluminum Oxide A/R C-406 * C-XXX numbers refer to the consumables list in BHT-ALL-SPM Standard Practices Manual SPECIAL TOOLS: None required. ### Page 3 ASB 412-CF-13-52 Page 3 of 4 ECCN EAR99 WEIGHT AND BALANCE: Not affected. ELECTRICAL LOAD DATA: Not affected. REFERENCES: C-12-146-000/MY-001 Illustrated Parts Breakdown C-12-146-000/MF-001 Maintenance Manual C-12-146-000/MP-001 Component Repair and Overhaul Manual PUBLICATIONS AFFECTED: C-12-146-000/MF-001 Maintenance Manual. ACCOMPLISHMENT INSTRUCTIONS: 1. Prepare helicopter for maintenance. -NOTE- Removal of the tail rotor blades is not required for this inspection. 2. Clean each tail rotor blade by hand us ing mild soap and cheesec loth (C-486) in a spanwise direction. Dry thoroughly. 3. Carry out a detailed visual inspection of both sides of the entire blade with a 3X magnifying glass and a bright light. Ins pect the tail rotor blade skin, leading edge spar, doublers, grip plates and trailing edge for cracks, corrosion, nicks, dents and scratches. Refer to Maintenance Manual for damage limits. 4. Carry out a further detailed visual ins pection with 10X magnifi cation of the shaded area shown in Figure 1 between stations 20 .00 to 35.00 of both sides of the blade with a bright light. 5. If any blistering, peeling, flaking, bubbling or cracked paint is detected, remove the paint from the affected area by s anding in a spanwise direction only with an abrasive cloth or paper (C -406) 240 grit or finer and a final sanding using an abrasive cloth or paper (C- 406) 400-grit or finer. After paint removal, visually inspect the affected area for damage us ing a 10X magnifying glass. Damage beyond the limits of the Maintenance Manual requires blade removal from service. ### Page 4 ASB 412-CF-13-52 Page 4 of 4 ECCN EAR99 6. Only superficial corrosion that can be removed with aluminum wool or very fine grade abrasive pad (C-407) is permissible. Corrosion on the spar 0.003 inch deep or less is acceptable when polished out. Replace any blade that has corrosion on the spar greater than 0.003 inch. 7. If a nick, scratch or dent is found, visu ally inspect for crack using a 10X magnifying glass or higher, and measure the dept h of the damage. (A digital optical micrometer is one tool that can be used for this measurement). 8. Repair damage and/or co rrosion found on tail rotor bl ades in accordance with the Maintenance Manual. 9. Replace any blade that has a cr ack. No cracks are permitted. 10. If paint was removed during the above steps, carry out paint touch up/refinishing as per C-12-146-000/MP-001, Chapter 64. 11. Make an entry in the helicopter logbook a nd historical service record to indicate accomplishment of this ASB. Enter exact lo cation of blend repair (if applicable) in the historical service record. Location shall include blade station as well as distance from the leading edge. Figure 1 --- 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.