57-13-05 HAMILTON STANDARD: Applies to All Hamilton Standard Aluminum Alloy Blades Used in Hydromatic (Noncounterweight Type) Propellers, With the Exception of Blades With Integrally Molded Chafing Rings (Refer Hamilton Standard Service Bulletin No. 508) and With the Exception of Those Blades Already Incorporating Corrosion Barriers Installed in Accordance With Service Bulletins Numbers 390, 414, and 414A, Provided This Corrosion Barrier is in Good Condition.
Compliance required as noted.
1. At each removal of propeller blade from hub after December 1, 1957, inspect for corrosion the shank area of blades not incorporating a corrosion barrier. Operators who have experienced corrosion in the shank area of any blade in the past 5 years and those who find corrosion during the above inspection must install the corrosion barrier except as outlined in 2.
2. Prior to September 1, 1957, or 450 hours of operating time after July 1, 1957, whichever comes first, for blades installed on P&W R2800 "B" type engines (Refer FAA Engine Listing) in C-46 aircraft.
Investigation of a recently failed blade revealed the existence of severe corrosion in the seal area at the shank. This blade did not incorporate a corrosion barrier as recommended by the manufacturer's Service Bulletins Numbers 390 and 414A. In order to minimize the possibility of additional blade failures due to corrosion in the shank area, disassemble the propeller and inspect this area in accordance with Hamilton Standard Service Bulletin No. 508. If no corrosion is present and none is suspected, install the corrosion barrier on each blade in accordance with the instructions contained in the bulletin. If corrosion, pitting, staining, or other conditions indicating chemical attack on the basic blade material are found, rework the shank area in accordance with the instructions contained in the bulletin. Remove from service any blade reworked below the minimum shank diameters tabulated in the bulletin. Install the corrosion barrier on each acceptable blade prior to assembly of the propeller.
(Hamilton Standard Service Bulletin No. 508 covers this same subject.)