All propellers and governors must be reworked at periodic intervals. Each Manufacturer publishes this information in the form of a Service Bulletin. Quite often an A.D. Note will require this rework before the component reaches its published TBO limit. These limits are established for actual time in service as well as calendar time in service.
When propellers are overhauled the purpose is to recondition, repair, and or replace worn components to bring the propeller back to an airworthy condition. Both hubs and blades are dimensionally checked for wear. If blades are worn beyond tolerance they must be replaced. Hubs that are worn can be furthur inspected and possibly repaired for return to service. After the initial dimension check, aluminum hubs receive an eddy current inspection, all mounting studs are removed, and the hubs are caustic etched, penetrant inspected, and chromic anodized. Steel Hubs are magnaflux inspected, cadmium plated, and baked for stress relief.
Blades are refinished, leading edges are trimmed and polished, and the blade shanks are reworked for close inspection including eddy current and visual for unusual wear or scratches in those critical areas. On Hartzell blades the bores must be polished, etched and penetrant inspected, then alodined and painted. Older Hartzell blades must have bronze bushings removed before these inspections and then new bushings installed and machined to final dimension. All blades are etched, penetrant inspected, and chromic anodized. Final rework is spraying with Polane Paint.
All manufacturer's have an established list of parts that must be replaced at each overhaul. This list includes seals and o-rings, mounting studs and nuts, blade ball and needle bearings, and all hardware. A.D. Notes, Service Bulletins and Service Letters may also mandate replacement of specific parts. We have a computer print out of all pertinent information for each propeller and this sheet is a permanent part of our work order package. We install all new parts as required by each manufacturer.
The propellers are reassembled with new parts and set to the specified torque values and blade angle settings. Propellers are lubricated, all parts are safetied, and then the prop is static balanced. A final inspection is made, paperwork is checked and completed, and the propeller is returned to service with log book entry and Maintenance Release.
For quotations on your propeller, please e-mail your request to Prop Center and include a fax or telephone number, or e-mail address and we will get a return answer back to you.
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