scope:

The SIN applies to all level crossings fitted with Frauscher wheel sensors as part of the Vamos Miniature Stop Light (MSL) system.

NOTE: Frauscher wheel sensors used for other purposes are outside the scope of this SIN. 

Purpose 

The purpose of this Special Inspection Notice (SIN) is to replace spring washers with Nord-Lock washers on the M24 fixing which secures the Frauscher wheel sensor rail claw to the rail at Vamos level crossings. This is to reduce the likelihood of 'phantom strike-out' events occurring. 

Following a wrong side failure event with a Vamos level crossing in 2022 it was identified that the rail claw used to secure the RSR123 wheel sensors to the rail could become loose. If a 'strike-out' wheel sensor and rail claw assembly becomes loose the resulting error condition can lead to a 'phantom strike-out' event and, potentially, a wrong side failure. 

NR/SIN/211 mandated that the torque of the rail claw is inspected and the M24 nut is tightened to 200Nm to reduce the potential for the assembly to become loose. 

NR/SIN/212 (this SIN) is intended to further reduce the potential for the assembly to become loose by mandating that the spring washer in the assembly is replaced with the more reliable Nord-Lock washer (NLX24). The requirement to tighten the M24 nut to 200Nm remains unchanged.