Starting fairly high level as I'm sure others will chime in:
Sole source suppliers
- it is best to ensure that your design is fairly robust and forgiving to variation from the supplier.
- if possible, ask for their inspection and monitoring data or at least have an effective IQA plan in place.
- shortages could be a problem so be very diligent around business continuity plans: floods, earthquakes, political upheaval for OUS, etc are a fact of life, how will you deal with this? (for example, excess inventory?)
- have a robust and well documented policy in your contract that explains the supplier change notification process and a robust validation process for any changes.
- How can you design a sole source parts out? this is long term but may be the only real protection you may have.
Critical Components, multiple suppliers: I assume these are 'off the shelf' parts?
- if off the shelf then again making sure your design is robust to variation
- if not off shelf, then ensure that you have identified all of the important characteristics, you have a good MSA with the supplier and yourself, the supplier(s) processes are capable, use SPC or other process controls as appropriate.
- have a robust and well documented policy in your contract that explains the supplier change notification process and a robust validation process for any changes.