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Regulations

Section 3039    
GROUND CHECK PRIOR TO TAKE-OFF

C. TEMPERATURE LIMITATIONS (Cont'd)

2.(Cont'd)

If it is necessary to prolong the run-up at high manifold pressure because of questionable pick-up or questionable single mag operation, a period of colling [[cooling]] off should be allowed, completely throttled until head temperatures get down to a low figure (350° maximum).

D. USE OF FLAPS

In operating under normal field and weather conditions, no wing flaps shall be used during take-off operation. If the field is muddy or covered with snow, it may be possible to get off the ground in less distance by using 25% of flap depression.

Measurements of trail take-offs using varying degrees of flap depression up to 40% have proven that the plane can be lifted off the ground in less distance using between 20% and 40% flap depression, but that the climb over and obstruction when taking off from a hard surface is equally as good when using no flap. The added safety of better single engine performance with flaps up makes it advisable to make all normal take-offs with flaps up.

When unusual circumstances such as muddy or snow covered fields are encountered, it may be advisable to increase the life of the wings at take-off speed by using 25% flap depression, which, if handled correctly, should get the plane clear of the ground quicker and clear obstructions at the end of the field a little better than with flaps up.

More than 25% flap depression should not be used with full gross load because of the poorer single engine flying qualities of the plane with large flap depressions. In addition to the fact that the planes flying qualities or single engine are unfavorable affected flaps may be damaged by mud and slush from the wheels during the take-off ground run.

For these reasons flaps will not be used where it is certain that the plane will clear all obstructions by a safe margin, but flap depression up to 25% may be used in cases where additional lift during take-off will be distinctly advantageous.

1/15/46                            
DC-3 GROUND OPERATION