APS brake discs are state-of-the-art CNC machined from a one-piece forging.
When the metal is forged it creates a directional grain flow that follows the contour of the disc. This allows for a much stronger disc that has a reduced risk of the cracking and catastrophic failures associated with the inferior welded design.
The APS "Black Steel" advantage is a proprietary heat treatment with a two-fold purpose. The heat treatment strengthens the steel by bonding the carbon, oxygen and nitrogen in the top layer of the metal. This is not a coating that can wear off. The steel itself is transformed. The heat treatment gives the steel its aesthetically pleasing black appearance and provides a surface with a high resistance to the corrosion and oxidation associated with the extreme thermal cycling experienced in aircraft braking systems. This makes it an excellent choice for agricultural aircraft that work in a harsh, chemical environment, as well as anyone who leaves their plane outside for most of its life.
WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov.
Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.
The main hole in the center is 4". The bolt holes are 1/4" and the friction surface is 0.21".