SERVICE BULLETIN SB274 B-40755A SPRAY HEAD ASSEMBLY REPLACEMENT

Full document text

SERVICE BULLETIN June 27, 2019 SB274 TITLE B-40755A SPRAY HEAD ASSEMBLY REPLACEMENT TO: FAA-Approved Propeller Repair Stations, Aircraft Manufacturers, STC Holders, Owners, and Operators MODELS AFFECTED The following model propellers are affected by this service bulletin: TABLE 1 4HFR34C778 Aircraft Affected The following aircraft models with the McCauley propellers installed listed in Table 1, are affected by this service bulletin: TABLE 2 Textron Aviation, Inc. Model 208B REFERENCE PUBLICATION MPC-26 - Owner/Operator Information Manual, Airplane Maintenance Manual REASON McCauley is introducing a new revision of the spray head assemblies installed as part of the C778 Caravan STC prop kit. Reports from the field indicate the rubber tubes that transfer TKS fluid from the slinger ring to the spray head nozzles can become separated from the spray head assemblies. The addition of a flare to the spray head assembly will help retain the rubber tube. The revised spray head assembly is identified as B-40755A, where the "A" that follows the part number identifies the new revision of the B-40755 part number. DESCRIPTION This service bulletin provides instructions to replace the B-40755 spray head assembly with the new B-40755A spray head assembly. For replacement parts and warranty consideration contact Customer Support via email at: productsupport@txtav.com, or by phone. Domestic (1-800-621-7767) or International (+1-316-831-4021) for any additional information. June 27, 2019 Page 1 of 2 TO OBTAIN SATISFACTORY RESULTS, PROCEDURES SPECIFIED IN THIS SERVICE INFORMATION MUST BE ACCOMPLISHED IN ACCORDANCE WITH ACCEPTED METHODS AND PREVAILING GOVERNMENT REGULATIONS. MCCAULEY PROPELLER SYSTEMS CANNOT BE RESPONSIBLE FOR THE QUALITY OF WORK PERFORMED IN ACCOMPLISHING THIS SERVICE INFORMATION. McCauley Propeller Systems PO Box 7704 Wichita, Kansas 67277-7704 COPYRIGHT © 2019 McCauley Propeller Systems SERVICE BULLETIN SB274 COMPLIANCE MANDATORY: This service bulletin must be accomplished within the next 25 flight hours or 30 Calendar days, whichever occurs first. NOTE: Accomplishment of this service bulletin should be done immediately if flight into known or forecasted icing conditions is anticipated. NOTE: All spray head assemblies must be replaced to the new B-40755A assembly. ACCOMPLISHMENT INSTRUCTIONS CAUTION: ALL FOUR SPRAY HEAD ASSEMBLIES MUST BE REPLACED TO THE B-40755A ASSEMBLY. MIXING THE B-40755 WITH THE B-40755A SPRAY HEAD ASSEMBLIES IS NOT PERMITTED. NOTE: All work must be performed by an authorized repair station. NOTE: Read and understand all of the instructions that follow before work is started on the propeller. 1. Remove the spinner shell and fillet assemblies per MPC26, McCauley Owner/Operator Manual: • Make an alignment mark on the spinner and an adjacent blade with a soft colored pencil. NOTE: This index mark is to insure accurate restoration of the spinner position to reduce the distortion of any dynamic balance already completed on the propeller assembly. • Remove the screws and washers from the spinner and fillet assemblies. • Remove the spinner from the bulkhead and fillet assemblies. • Remove the spinner support and shims from the spinner. • Remove the screws and washers that attach the fillets to the bulkhead and then remove the fillets. 2. Remove the (3) screws that hold the (4) B-40755 spray head assemblies in place and remove the assemblies. If balance weights and holder are installed in spray head assembly locations, remove the weights and holder with the spray head. Make note of the position and number of the weights. Discard the B-40755 spray head assemblies. 3. Install B-40755A spray head assemblies in the same locations as the removed B-40755 heads. Use the existing screws to reinstall any balance weights and holder and torque the screws to 30 to 36 in-lbs. Where no balance weights and holders were present, use (3) A1635-4 screws to install the spray head assembly and torque the screws to 30 to 36 in-lbs. Install A-1640-5 lockwire if lockwire was previously installed. If lockwire was not previously installed, apply A-1664-1 sealant to the threads of the screws and an A-1664-27 blue sentry stripe screw head to the weight or spray head assembly as applicable. 4. Reinstall the spinner shell and fillets: • Use the existing screws and washers to install the fillet assemblies in the same locations they were installed previously. • Torque the screws to 20 to 25 in-lbs. • Use shims to suit 1/2-hole misalignment. Push hard on the shell to align the holes and install (4) approximately equal spaced screws and washers. Relax the force and install the remaining screws and washers. • Torque the screws to 20 to 25 in-lbs. 5. Make a propeller logbook entry stating compliance with the service bulletin. SB274 Page 2 June 27, 2019