Section 12 Propellers

12.1.1 For details of design requirements, see Vol 2, Pt 4, Ch 1 Propellers

12.2.1 Castings are to be examined at the manufacturer's works.

12.2.2 All finished propellers are to be examined for material defects, and finish, and measured for dimensional accuracy of diameter and pitch. Propeller repairs by welding, where proposed, are to be in accordance with the requirements of Ch 9, 1 Castings for propellers of the Rules for Materials.

12.3.1 The bedding of the propeller with the shaft is to be demonstrated. Sufficient time is to be allowed for the temperature of the components to equalise before bedding. Alternative means for demonstrating the bedding of the propeller will be considered.

12.3.2 Means are to be provided to indicate the relative axial position of the propeller boss on the shaft taper.

12.4.1 The components of controllable pitch propellers are also subject to material tests, as in the case of solid propellers.

12.4.2 Examination of all the major components including dimensional checks, hydraulic pressure testing of the hub and cone assembly and the oil distribution box, where fitted, together with a full shop trial of the completed controllable pitch propeller assembly, is to be carried out.

12.5.1 After verifying that the propeller and shaft are at the same temperature and that the mating surfaces are clean and free from oil or grease, the propeller is to be fitted on the shaft under survey. The propeller nut is to be securely locked to the shaft.

12.5.2 Permanent reference marks are to be made on the propeller boss nut and shaft to indicate angular and axial positioning of the propeller. Care is to be taken in marking the inboard end of the shaft taper to minimise stress raising effects.

12.5.3 The outside of the propeller boss is to be hard stamped with the following details:
For oil injection method of fitting, the start point load, in Newtons, and the axial pull-up at 0ºC and 35ºC, in mm. For the dry fitting method, the push-up load at 0ºC and 35ºC, in Newtons.

12.5.4 A copy of the fitting curve relative to temperature and means for determining any subsequent movement of the propeller are to be placed on board.

12.6.1 The fit of the screwshaft cone to both the working and any spare propeller is to be carried out under survey. Generally, a satisfactory fit for keyed type propellers should show a light, overall marking of the cone surface with a tendency towards heavier marking in way of the larger diameter of the cone face. The final fit to cone should be made with the key in place.