Section 238.227 - Suspension systemOn or after November 8, 1999-
(a) All passenger equipment shall exhibit freedom from truck hunting at all operating speeds. If truck hunting does occur, a railroad shall immediately take appropriate action to prevent derailment. Truck hunting is defined in § 213.333 of this chapter.(b) Nothing in this section shall affect the requirements of the Track Safety Standards in part 213 of this chapter as they apply to passenger equipment as provided in that part. In particular- (1)Pre-revenue service qualification. All passenger equipment intended for service at speeds greater than 90 mph or at any curving speed producing more than 5 inches of cant deficiency shall demonstrate safe operation during pre-revenue service qualification in accordance with § 213.345 of this chapter and is subject to the requirements of either § 213.57 or § 213.329 of this chapter, as appropriate.(2)Revenue service operation. All passenger equipment intended for service at speeds greater than 90 mph or at any curving speed producing more than 5 inches of cant deficiency is subject to the requirements of § 213.333 of this chapter and either § 213.57 or § 213.329 of this chapter, as appropriate. 78 FR 16125 , Mar. 13, 2013