OOSC, Part II, Item 1. Brake Systems, a. Defective Brakes (5) (b) - 20 Percent Rule

Clarification is needed in Part II, number 1, section a.(5)(b) of the NAS OOSC. This section deals with brakes found to be beyond the maximum adjustment limit, but not by 1/4 inch or more. While instructing NAS Level I courses and conducting inservice training I have found the current language and explanation to be confusing to the students.

The current verbage is less than clear on how to deal with brake adjustments beyond the maximum limit by less than 1/4 inch. The minimum measurement used are in eights of an inch so this needs to be reiterated in the section. Language is also needed to clarify that all brakes found beyond the maximum adjustment limit need to be repaired if the 20 percent criteria is met.

The section needs to be changed to reflect the proposed language: 1.a.(5)(b) Two (2) brakes 1/8 inch (3mm) beyond the maximum adjustment limit are considered one (1) defective brake. (Example: Type 30 clamp type brake chamber pushrods measure - Two (2) at 2-1/8 inches (54mm). All brakes found beyond the maximum adjustment limit on a vehicle or combination of vehicles must be repaired if the total number of defective brakes is equal to or greater than 20% of the total number of brakes. OR 1.a.(5)(b) Brakes found beyond the maximum adjustment limit by less than 1/4 inch (6mm) - (Example 1/8 inch (3mm), shall be considered .5(1/2) a defective brake for determining the number of defective brakes per the NAS OOSC 20% defective brake criterion. All brakes found beyond the maximum adjustment limit on a vehicle or combination of vehicles must be repaired if the total number of defective brakes is equal to or greater than 20% of the total number of brakes.