Maintenance for 14SF Propellers (DHC-8, ATR42, ATR72)
this article as a .pdf.
Many times erosion will start between the blade collars and the blade heater. If this problem is not corrected erosion will cause the coating to wear out to the point that moisture will penetrate into the foam core rejecting the blade.
If this condition starts to happen PRC is recommended to be put over the eroded area to stop this condition.
If pitting is occurring to the point it starts to show fibreglass this could be cause for moisture to enter the blade and could cause fibreglass erosion or even moisture to enter the blade, once moisture starts to enter the blade foam area it starts to delaminate the blade and this moisture may never come out of the foam, causing blade rejection.
If the erosion film over the de-icer heater is loose or starts to get pin holes it should get changed this is like a protective film over the heater for protection.
Keep the erosion coating intact on the airfoil portion of the blade. Sunlight causes the fibreglass to degrade.
Blade Retaining Rings
The blade retaining rings helps keep the blade secure in the hub. The retaining rings are coated with a Teflon type paint which reduces friction between the retaining ring surface and the blade, quite often this coating will wear and can cause for either damage to the retaining ring and blade shank. There is minimal repair limit for either component.
The area between the blade retaining ring and the blade hub is a common place where oil and dirt to accumulate and if this is not clean on a regular basic this will cause retaining ring and blade shank corrosion.
There are 7 quarts of Turbine oil in the hub this oil should get replace at 500 hour intervals. This should reduce that amount of corrosion setting in on the internal parts of the hub. There is a corrosion preventative compound that can be added. See service bulletin 61-115
Quick over view
Fill pin holes with paint to stop blade erosion
Replace de-icer film when film starts to erode, come loose or has pin holes.
Just behind blade collar paint may start to wear, add PRC to reduce wear.
Watch for Teflon wear, oil, grease and dirt mixture between retaining ring and Hub. If propeller is not used for 1 year or more remove all retaining rinds and clean rings shims and hub then reinstall rings.
Change oil if propeller is not going to going to be used.