LOT Polish Airlines Flight 7 increased engine wear, since the engines were under greater load. NK-8-4 engines were not reliable enough. Warranty service life was only 5000 hours, and about half of LOT engines failed after 2000–3000 hours. Because of this, Polish pilots often called the Il-62 "flying coffins". In spite of the low reliability, the airline decided to increase overhaul life intervals to reduce the frequency of repairs, which were carried out in Soviet factories and quite expensive. LOT sent a letter to the Ilyushin Design Bureau containing the results of a test in which it was found that the engines could operate normally
Three letter rule Three letter rule In English spelling, the three letter rule (or short word rule) is the observation that one- and two-letter words tend to be function words such as "I", "at", "he", "if", "of", "or", etc. As a consequence of the rule, "content words" tend to have at least three letters. In particular, content words containing fewer than three phonemes may be augmented with letters which are phonetically redundant, such as "ebb, "add, "egg, "inn, "bee, "awe, "buy", "owe", etc. Many content words would be homographs of common function words if not for the latter's "redundant" letters: e.g. "be/bee", "in/inn",