We have all read about Hartzell A.D. 97-18-02 that will affect thousands of older airplanes. Here are the inspection requirements that are required by the Service Bulletin #217 as specified in the A.D. Note.
This Bulletin provides for:
(1) Inspection of the retention area of double shoulder (X and V shank) blades which include fluorescent dye penetrant inspection and new procedures for eddy current inspection.
(2) Optical comparator inspection of the blade reteintion area.
(3) Dye penetrant inspection of the blade internal bearing bore radius.
(4) Magnetic particle inspection of all blade clamps.
(5) Magnetic Particle inspection of certain hubs.
All items except the eddy current inspections have been addressed in older Service Bulletins. Item No. 3 requires the old P/N A127 bushing be removed from the blade butt, the bore polished to remove scratches or corrosion ( also checked for maximum dimensions), penetrant inspect, alodine, and finally Polane Paint. A new bushing must be installed and machined to proper dimension. This procedure is required at each propeller overhaul. Here is a photo showing a blade with the bushing removed and you can see the scratches and wear found inside the blade bore.
All of the propellers listed in this Bulletin have propellers that were designed 40 to 50 years ago, and probably have not been inspected thoroughly. The most serious inspections are required on propellers with the 82 or 83 series hubs. Item No. 5 requires inspection of this type of hub. They have a solid blade bearing installed with split ring keepers that retain the bearing on the hub. ( Quite similar to valve spring keepers). This is quite a load on a small area. Older A.D. Notes require the use of updated P/N A969 retainers with A14B bearings.
An optical comparator is used to verify the correct shape and dimension of the blade butt. We have specifications for the correct height of each surface on the blade butt and must check for excessive wear or possibly an improper repair. This area must be shotpeened.
If this information has not fully answered your questions, please contact Prop Center, and we will answer every request for clarification. We are Eddy Current Qualified to perform these inspections. We are an F.A.A. Approved Propeller Repair Station No. PC7R081J and have the tooling in house to perform the rework as called out in this bulletin.
It is also possible to retrofit a later style propeller with an STC. Please check our STC pages for current popular applications.