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ways, including ground handling, takeoff, landing, and
flight operations. Some manufacturers provide recommended
procedures and performance data in the
Airplane Flight Manual (AFM) and/or Pilot’s
Operating Handbook (POH).
Title 14 of the Code of Federal Regulations (14 CFR)
part 61 does not require specific pilot training and
authorization to operate skiplanes; however, it is
important to train with a qualified skiplane flight
instructor.
Since most skiplanes operate in a wide variety of conditions,
such as landing on frozen or snow-covered
lakes and sloping glaciers, with varying qualities of
snow, it is important to know how performance is
affected. Use the performance data provided by the
manufacturer.
CONSTRUCTION AND MAINTENANCE
Modern airplane ski designs are a compromise for the
various forms and conditions of snow and ice. For
example, a long, wide ski is best for new fallen, powdery,
light snow, whereas a sharp, thin blade is best
for hard-packed snow or smooth ice. Many ski
designs feature a wide, flat ski with aluminum or steel
runners on the bottom. Airplane skis may be made
from composites, wood, or aluminum, and some have
a polyethylene plastic sheathing bonded or riveted to
the bottom surfaces. Ski designs fall into two main
categories: plain and combination. Plain skis can only
be used on snow and ice, while combination skis also
allow the wheels to be used to land on runways.
PLAIN SKI TYPES
• Wheel Replacement—Wheels are removed and
ski boards are substituted. [Figure 7-2]
• Clamp-On—Skis that attach to the tires and
benefit from the additional shock absorbing
qualities of the tires.
• Roll-On or Full Board—Similar to the clamp-on
type except the tires are bypassed and do not carry
side or torque loads. Only the tire cushioning
effect is retained with this installation.
COMBINATION SKI TYPES
• Retractable Ski—Can be extended into place for
snow operations or retracted for non-snow operations.
This is accomplished by either a hydraulic
pump or crank.
Figure 7-1. Skiplane.
Figure 7-2. Wheel replacement ski.
Ch 07.qxd 8/25/04 11:20 AM Page 7-1
7-2
• Penetration Ski—The wheel extends down partially
below the ski, allowing the skiplane to
operate from both snow and non-snow surfaces.
This type of ski gives poor ground clearance on
non-snow surfaces and causes extra drag when
on snow. [Figure 7-3]
The plastic polyethylene sheathing on the bottoms of
the skis may be punctured by sharp objects, including
ice. It also may shatter from impacts in extremely cold
temperatures. Replacing the bonded type sheathing is
very difficult in the field. If the sheathing is riveted,
machine screws may be used to secure loose sheathing,
but the screw holes must provide for expansion and
contraction. Follow the manufacturer’s recommendations
for patching limited sheathing damage. If
damage is extensive, the entire ski bottom may need
new covering.
Shock cord bungees used in ski rigging deteriorate
rapidly when left under tension. When parking the
skiplane overnight, detach the bungees at the lower
fitting and allow them to hang free. Reattaching the
bungees normally requires two or more people.
Hydraulic ski retracting mechanisms usually function
well in cold environments, but the small, abrupt change
of ski attitude occurring at touchdown imposes a severe
load on the external hydraulic lines leading to the skis.
These lines are a more prevalent source of trouble than
the internal parts.
Use low temperature oils and greases to lubricate friction
points. For lubrication requirements, see the
AFM/POH or the ski manufacturer’s manual.
The condition of the limiting cables and their fastenings
is important to safety in flight. Be sure there is no
fraying, kinking, rusting, or other defective condition
before each flight.
OPERATIONAL CONSIDERATIONS
In the air, skiplane flight characteristics are similar to
those of airplanes with standard landing gear, except
for a slight reduction in cruising speed and range.
Leaving the skis in the extended position in flight produces
no adverse effect on trim, but may cause a slight
loss of speed. Consult the operator’s manual for
skiplane performance data, and weight and center of
gravity considerations.
The AFM/POH skiplane supplement may provide limitations
including limiting airspeeds for operation with
skis in flight and for other wheel/ski configurations.
These speeds may be different from the wheel-type
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