CHAPTER 7—Skiplane Operations


Adequately preheat the engine, battery, and the cockpit instruments before startup and departure. Sometimes engine oil may require heating separately. Check the manufacturer’s recommendation for starting the engine when ambient temperatures are below freezing.

Batteries require special consideration. In cold climates a strong, fully charged battery is needed. With just a little cold-soaking, the engine may require three times the usual amperage to crank the engine.

Another consideration is the electrolyte freezing point. A fully charged battery can withstand temperatures of -60 to -90° F since the electrolyte’s specific gravity is at a proper level. Conversely, the electrolyte in a weak or discharged battery may freeze at temperatures near 32° F. If a fully charged battery is depleted by an unsuccessful start, it may freeze as it cools to ambient temperature. Later, when the engine is started and the battery is receiving a charge, it could explode.

After start, a proper warmup should be completed prior to a runup and high power settings. Perform the warmup according to the engine manufacturer’s recommendations. Some manufacturers recommend a minimum of 1,000 r.p.m. to ensure adequate lubrication.

If the skiplane is parked on heavily crusted snow or glaze ice with the skis frozen to the surface, it may be possible to start the engine and perform the runup in the parking area. Be sure the area behind the skiplane is clear, so as not to cause damage with the propeller wash. If a ski should become unstuck during the runup, reduce power immediately. Then use one of the following procedures to secure the airplane.

Tie down or chock the skiplane prior to engine start, warmup, and runup. Keep all ropes, bags, etc., clear of the propeller. After warmup is complete, and if no assistance is available, shut down the engine to untie and unchock the skiplane, then restart as quickly as possible. If a post, tree, boulder, or other suitable object is available, tie a rope to an accessible structural component in the cockpit, take the end around the anchor object, bring it back to the cockpit, and tie it off with a quick-release knot. When the warmup and runup are complete, release the knot and pull the rope into the cockpit as the skiplane begins to taxi.

If tiedowns or chocks are not available, build small mounds of snow in front of each ski. The mounds must be large enough to prevent the skiplane from taxiing over them during engine start and warmup, but small enough to allow taxiing when power is applied after the warmup is complete. If tiedowns or means to block the skis are not available, the runup can be accomplished while taxiing when clear of obstacles or other hazards. [Figure 7-4]

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