The S1915-1 is an aircraft-grade noise suppression capacitor, also referred to as an RFI (radio frequency interference) or alternator noise filter. It is used in aircraft electrical systems to reduce electrical noise generated by components such as alternators, generators, ignition systems, and other DC electrical loads.

It is typically installed in the aircraft electrical bus or near the alternator output to stabilize avionics performance and prevent interference in radios, navigation systems, and instrument displays.

This part is commonly found in Cessna airframe electrical systems and is cataloged as a filter/capacitor assembly rather than a generic electronic capacitor due to its certified aviation use.

Key features include:

Aircraft RFI / EMI noise suppression capacitor
Used to reduce alternator and electrical system interference
Installed in aircraft electrical bus or alternator circuit
Improves radio and avionics signal stability
Certified aviation OEM component (Cessna/Textron designation)
Designed for vibration, temperature, and continuous aircraft operation
Encased filter-capacitor construction
Supports avionics noise reduction (COM/NAV systems)
Replacement part used in certified maintenance environments
Often cross-referenced as an “Alternator Noise Filter” or “RFI Filter”