d be symmetrical with it. Next, sight each interplane front
strut with its rear strut. They should be parallel.

Then, standing on one side of the aeroplane, sight all the front struts.
The one nearest to you should cover all the others. This applies to the
rear struts also.

Look for distortion of leading edges, main and rear spars, trailing
edges, tail-plane, and controlling surfaces.

This sort of thing, if practised constantly, will not only develop
an expert eye for diagnosis of faults, but will also greatly assist in
impressing upon the memory the characteristics and possible troubles
of the various types of aeroplanes.

MISHANDLING ON THE GROUND.--This is the cause of a lot of unnecessary
damage. The golden rule to observe is, PRODUCE NO BENDING STRESSES.

Nearly all the wood in an aeroplane is designed to take merely the
stress of direct compression, and it cannot be bent safely. Therefore,
in packing an aeroplane up from the ground, or in pulling or pushing it
about, be careful to stress it in such a way as to produce, as far as
possible, only direct compression stresses. For instance, if it is
necessary to support the lifting surface, then the packing should be
arranged to come directly under the struts so that they may take the
stress in the form of compression for which they are designed. Such
supports should be covered with soft packing in order to prevent the
fabric from becoming damaged.

When pulling an aeroplane along, if possible, pull from the top of the
undercarriage struts. If necessary to pull from elsewhere, then do so by
grasping the interplane struts as low down as possible. Never pull by
means of wires.

Never lay fabric-covered parts upon a concrete floor. Any slight
movement will cause the fabric to scrape over the floor with resultant
damage.

Struts, spars, etc., should never be left about the floor, as in such
position they are likely to become scored. I have already explained the
importance of protecting the outside fibres of the wood. Remember also
that wood becomes distorted easily. This particularly applies to
interplane struts. If there are no proper racks to stand them in, then
the best plan is to lean them up against the wall in as near a vertical
position as possible.

TIME.--Learn to know the time necessary to complete any of the various
rigging jobs. This is really important. Ignorance of this will lead
to bitter disappointments in civil life; and, where Service flying