Care of Propellers.—The care of propellers is of the greatest importance, as they become distorted very easily.

1. Do not store them in a very damp or a very dry place.

2. Do not store them where the sun will shine upon them.

3. Never leave them long in a horizontal position or leaning up against a wall.

4. They should be hung on horizontal pegs, and the position of the propellers should be vertical.

If the points I have impressed upon you in these notes are not attended to, you may be sure of the following results:

1. Lack of efficiency, resulting in less aeroplane speed and climb than would otherwise be the case.

2. Propeller "flutter" and possible collapse.

3. A bad stress upon the propeller shaft and its bearings.