The report also states they had 54 computer messages warning them about various system failures. The plane also became tail heavy, and safety experts said that may have posed the greatest risk.
If the plane got too far out of balance, the jetliner would lose lift, stall and crash.
The pilots managed to return the crippled plane to Singapore on Nov. 4 and land safely, with 450 passengers aboard.
Qantas grounded all of its six A380s shortly after the incident and four days later, the company said checks had revealed suspicious oil leaks in three engines on three different grounded A380s.
Meanwhile, Qantas said up to half of the Rolls Royce engines used on its super jumbo jets may have to be replaced.
Two other carriers, Singapore Airlines and Lufthansa, also use the same type of engines.
The Associated Press contributed to this report.