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Snow Ski Installation

Proper tricycle installation Ready to fly

Proper installation of the MMP Snow Skis is important for maximum performance.

Brief installation procedures:

  1. Install main gear skis parallel to wing.
  2. Nose gear ski should be slightly nose high.
  3. Do not use a tail ski. It will likely catch on ice, and can rip your rudder off of your airplane. Possibly even the entire tail.
  4. You must clean and dry all oils off of your axles before installing skis.
  5. Ensure you have proper axles. And ensure that they are tight and cannot rotate under load.
  6. Don't over tighten set screws. Don't remove screws from lock block once the screw tips have been deformed on the axles. Or, it may strip the aluminum lock block.
  7. Carefully oversize axle holes to 1/4" if needed. A tight fit is necessary.

Detailed installation procedures:

  1.  MMP Snow Skis should always be installed parallel to the wing! Especially in the Tail Dragger configuration. Due to the leaf spring design, if they are installed with the tips nose high, the springs will influence the airframe into a nose-down condition on takeoff and landing. It will also cause unnecessary trim changes in the air! They are self centering skis, NOT free floating bungee skis, and should NOT be installed nose high.
  2. The only exception is the nose gear ski on tricycle configurations. Due to the spring coil in most nose gears, the nose landing gear wire tends to flex rearward. When this happens the ski tends to rotate slightly nose down, reducing flotation. So, a slight nose up installation of the nose ski only, is desirable. When setting the nose gear skis up on the bench. Simply prop up the front of the ski, very slightly, with something like a pen or a piece of wood. It should not be tipped much, just a little bit nose high. 
  3. A tail ski is not recommended (or supplied) as it can easily grab snow and ice and tear the rudder off of the plane, or worse. And that is a bad thing. The tail wheel will provide ample steering, and the rear of the fuselage will provide plenty of flotation that is necessary on the snow. 
  4. Your axles NEED to be CLEAN, and DRY, when the skis are installed. The set screws are relying on a tight, slop-free, friction fit, to hold the skis tightly on the axles. Oil reduces friction. 'Nuff said. Any fuel and oil dripping, and soaking, on axles is something that can undermine the skis otherwise premium performance! Remove all wheel and axle lubricants and contamination before installing skis! 
  5. Make very certain that your AXLES ARE TIGHT! Use of (5/32") axles with a large mounting stud, and nut, is highly recommended when using aluminum or fiberglass landing gear. If the ski holds tight, but the axle spins, you have undermined the design! Screws do not constitute proper axles. See photo below. 
  6. The set screws are 8-32 grade 8 hardware on the newer skis, and 6-32 stainless steel on the older ones. Both of the screw tips will deform slightly to the contour of the axle when tightened onto the axles. This helps them to grip the axle. Therefore, do not back the screws all the way out into the aluminum threads, once they have been installed tightly onto an axle. Or, you can subsequently damage the threads in the lock block. Don't over torque the set screws. if you do accidentally over-torque, and snap off a lock block screw, these skis have been designed with enough aluminum material so that the screw can be extracted, and if the threads are damaged in doing so, they will accommodate an oversized set screw. They can also be drilled for a new screw, in a new location entirely. This is an intentional design feature. Repair-ability. 
  7. If your plane falls in a weight range where you prefer using 1/4 inch axles, the MMP skis are designed to accommodate being carefully oversized to match the 1/4 inch axles. BE CAREFUL, and make as close of a tolerance fit as possible. Sloppy over-sizing of the axle holes is a perfect way to reduce the tight friction fit required to hold the skis tightly on the axles!