727-100 Lcn

[Airways Ed]

Would be grateful to learn what the 727-100's LCN (Load Classification Number) is both for rigid and flexible pavements.

Many thanks

[OverRun]

727-100 LCN?

The LCN system is probably older than the 727-100, and is likewise headed for the great graveyard in the sky; not without good reason some say. LCN depends on the aircraft weight, pavement type, and the actual thickness of runway/pavement provided. It is a bit of a chicken and egg situation. It has been replaced by the much better ACN/PCN system, and seems to be no longer used except for kangaroo ATPL exams, the military, and some obscure South American and African airports. These comprise much of Boeing's market of course ;)

Fortunately, as I dust off my Stratocruiser handbook and pull out my slide rule, some answers are here somewhere.

For flexible pavements (which are coloured black, and also called asphalt or bituminous), the LCN at 727-100 maximum takeoff weight of 160,000 lbs (72,570 kg) is between 55 and 100, depending on how thick the pavement is. Applying that oxymoron of note - the intelligent guess - for most runways the LCN should be at least 65-75. If the airport is in the middle of a swamp, it might need to be higher such as 80-90, and if it's built on an rock, it could be as low as 50.

If you are after the LCN of an apron for long term parking, and assuming the aircraft is parked up empty and has not got too much fuel inside, the LCN for the apron could drop to a typical figure of 40 or above.

For rigid pavements (which are coloured white, and also called concrete), the radius of relative stiffness comes into the equation, and using the intelligent guess, the LCN values typically rise slightly - add 5 to the values above as a rule of thumb.