57-16-04 HAMILTON STANDARD: Applies to all Hamilton Standard Two-Flyweight Models 4U18 and 5U18 Governors.
Compliance required as indicated.
To prevent the possible occurrence of propeller reversal resulting from oil leakage caused by the mounting holes in the governor body being drilled beyond tolerances, the following must be accomplished:
A. Prior to the installation of new or overhauled governors of the above models, perform the following, except that it need be accomplished only once for each governor affected, and need not be accomplished if paragraph C is complied with:
1. Remove reverse solenoid valve assembly.
2. Thoroughly clean the solenoid valve mounting hole in the governor body as described in Hamilton Standard Service Bulletin No. 518.
3. Measure the depths of the hole to the deepest point.
4. Governor bodies having a hole exceeding 0.490 inch deep shall not be used until inspected as specified by paragraph C.
B. If the reverse solenoid is loosened or removed while in service, comply with paragraph A unless already accomplished.
C. As soon as practicable, but not later than next overhaul of all governors of the above models, comply with the inspection outlined in Hamilton Standard Service Bulletin No. 518. Governor bodies having a wall thickness between the solenoid attaching stud hole and the low pressure relief valve passage of less than 0.035 inch should not be returned to service. If the provisions of Service Bulletin No. 518 have been complied with, it will not be necessary to repeat.
(Hamilton Standard Service Bulletin No. 518 covers this same subject.)
This supersedes telegraphic instructions dated July 12, 1957.