Testing on the ground had shown that the service propulsion system (SPS) engine had a small chance of exploding when burned for long periods unless its combustion chamber was "coated" first by burning the engine for a short period.
tˈɛstɪŋ ɔnðə ɡɹˈaʊnd hæd ʃˈoʊn ðætðə sˈɜːvɪs pɹəpˈʌlʃən sˈɪstəm ˌɛspˌiːˈɛs ˈɛndʒɪn hæd ɐ smˈɔːl tʃˈæns ʌv ɛksplˈoʊdɪŋ wɛn bˈɜːnd fɔːɹ lˈɔŋ pˈiəɹɪədz ʌnlˈɛs ɪts kəmbˈʌstʃən tʃˈeɪmbɚ wʌz "kˈoʊɾᵻd" fˈɜːst baɪ bˈɜːnɪŋ ðɪ ˈɛndʒɪn fɚɹə ʃˈɔːɹt pˈiəɹɪəd.