Complex sentence: The Super Frelons also took part in the Israeli invasion of Lebanon in June 1982 due to relatively high maintenance cost and poor performance capabilities compared to the IAF CH-53's, they were finally retired in 1991.
Split into simpler sentences: The Super Frelons also took part in the Israeli invasion of Lebanon in June 1982. Due to their relatively high maintenance cost and poor performance capabilities compared to the IAF CH-53's, they were finally retired in 1991.