In the following passage, some words have been deleted. Read the passage carefully and select the most appropriate option to fill in each blank.

A giant plane carrying 43 passengers was (1) ______ to crash-land when its landing gear got (2) ______. Only the skill of the pilot was able to (3) ______ a major tragedy. Expert mechanics laboured (4) ______ hours before they could find the (5) ______ of the mechanical failure.