Over Weight landing on One enginer - RW Document
Posted: Sun Jun 21, 2009 2:01 am
LANDING GUIDANCE IN THE EVENT OF ENGINE SHUTDOWN
Recently Flight Operations requested guidance from Boeing for landing overweight following precautionary shutdown of an engine: should the aeroplane continue to circle until its weight is reduced below maximum landing weight, or should an overweight landing be performed?
Boeing’s position is that the decision to dump fuel or to land overweight is firstly an airline policy decision based on the economics of their particular operation, and secondly an operational decision that can only be made by the captain involved after considering the factors existing at the time.
Each option has advantages and disadvantages. Landing at higher weights reduces landing performance margins, but shortens the flying time with a malfunctioning system. On the other hand, dumping fuel retains performance margins, but may expose the aeroplane to additional system deterioration.
FAA certification requires that Boeing aeroplanes be designed for a 10 ft/s sink rate at maximum design landing weight, and a 6 ft/s sink rate at maximum design take-off weight. Typical sink rates at touchdown are approximately 2 – 3 ft/s, and a "typical" hard landing rarely exceeds 6 ft/s. Additionally, design landing loads are based on the worst possible landing attitudes resulting in high loading on individual gear. Consequently, Boeing aeroplanes have adequate strength margins and are capable of occasional operation at weights above the maximum certified landing weight.
Operation above maximum landing weights does impose larger than nominal stresses on the aeroplane and these may have an eventual effect on fatigue life.
However, Boeing has no statistical data on this, and believes that these effects can be minimised by taking advantage of this capability infrequently.
The Boeing maintenance manual recommends a special inspection any time an aeroplane is landed overweight, regardless of how smooth the landing. The inspection looks for obvious signs of structural distress such as wrinkled skin, popped fasteners, or bent components in areas which are readily accessible. Only if definite signs of overstressing are found does a more rigorous inspection need to be carried out. The initial inspection can typically be accomplished in 2 – 4 hours. The length of the overweight landing inspection is generally not a problem, since an aeroplane that has returned or diverted normally has a problem which takes longer to clear than the inspection itself.
Recently Flight Operations requested guidance from Boeing for landing overweight following precautionary shutdown of an engine: should the aeroplane continue to circle until its weight is reduced below maximum landing weight, or should an overweight landing be performed?
Boeing’s position is that the decision to dump fuel or to land overweight is firstly an airline policy decision based on the economics of their particular operation, and secondly an operational decision that can only be made by the captain involved after considering the factors existing at the time.
Each option has advantages and disadvantages. Landing at higher weights reduces landing performance margins, but shortens the flying time with a malfunctioning system. On the other hand, dumping fuel retains performance margins, but may expose the aeroplane to additional system deterioration.
FAA certification requires that Boeing aeroplanes be designed for a 10 ft/s sink rate at maximum design landing weight, and a 6 ft/s sink rate at maximum design take-off weight. Typical sink rates at touchdown are approximately 2 – 3 ft/s, and a "typical" hard landing rarely exceeds 6 ft/s. Additionally, design landing loads are based on the worst possible landing attitudes resulting in high loading on individual gear. Consequently, Boeing aeroplanes have adequate strength margins and are capable of occasional operation at weights above the maximum certified landing weight.
Operation above maximum landing weights does impose larger than nominal stresses on the aeroplane and these may have an eventual effect on fatigue life.
However, Boeing has no statistical data on this, and believes that these effects can be minimised by taking advantage of this capability infrequently.
The Boeing maintenance manual recommends a special inspection any time an aeroplane is landed overweight, regardless of how smooth the landing. The inspection looks for obvious signs of structural distress such as wrinkled skin, popped fasteners, or bent components in areas which are readily accessible. Only if definite signs of overstressing are found does a more rigorous inspection need to be carried out. The initial inspection can typically be accomplished in 2 – 4 hours. The length of the overweight landing inspection is generally not a problem, since an aeroplane that has returned or diverted normally has a problem which takes longer to clear than the inspection itself.