(a) * * *
(3) Each turbine engine must comply with one of the following paragraphs:
(i) Section 33.68 of this chapter in effect on January 5, 2015, or as subsequently amended; or
(ii) Section 33.68 of this chapter in effect on February 23, 1984, or as subsequently amended before January 5, 2015, unless that engine's ice accumulation service history has resulted in an unsafe condition; or
(iii) Section 33.68 of this chapter in effect on October 1, 1974, or as subsequently amended prior to February 23, 1984, unless that engine's ice accumulation service history has resulted in an unsafe condition; or
(iv) Be shown to have an ice accumulation service history in similar installation locations which has not resulted in any unsafe conditions.
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