Quote:
Originally Posted by Mr Quatro
Southwest airlines has a strange take off policy that i have witnessed. They take off in a hurry and then head straight up at a larger angle than the other airlines that take off before and after they do.
|
this is sometimes required by noise abatement or obstacle clearance procedures in effect for specific airports. What makes southwest standout is that they operate one single fleet type, where other airlines operate a variety of fleet types. So, you may see what appears to be exaggerated climb performance from a 737-400 when compared to that of say, an MD-80 or a 747 or even a Cessna 172 performing the exact same noise abatement procedure because climb performance will be significantly different between models.
Quote:
Originally Posted by Mr Quatro
I wonder if this could add to more stress on the engines after a lot of these tak off's?
|
not likely. The engine parameters used in the calculation of takeoff power are dictated by the manufacturer and account for weight and atmospheric conditions. For example, given the "known data" of aircraft weight, atmospheric pressure, humidity, density and temperature, the manufacturer's data would provide a given N1 Power setting to be used for takeoff and can be computed manually or electronically. Lets assume the manufacturer's data said to use an N1 Speed of 92% for takeoff given the current atmospheric and weight conditions; that would be the N1 speed used, and by all available information provided by the company that built the engine, it would be within the capabilities of the engine to handle it.
climbing more steeply (or conversely - adopting a more shallow climb) would not change the N1 speed by any measurable amount (if at all). Only the indicated airspeed and rate of climb resultant from the available amount of power would be affected, and these shouldn't have any bearing on the structural integrity of the engine components.
given that you have this type of fan blade failure in two CFM-56 type engines would normally point to a manufacturer defect.
however, the CFM-56 is in use aboard a number of different air-frames with both civil and military operators.
given that both failures occurred with the same airline would be an indication that either the in house maintenance is the origin of the issue, or some flight procedure specific to southwest is the origin of the issue. So your takeoff theory is not very far off base. but "flight procedures" can encompass everything from startup to shut down and all phases of the flight in between.
An error in manufacturing could impact the entire CFM-56 type, or only a specific run produced during a specific time range. (of which southwest may be the sole purchaser for a specific run)
the other end of the investigation needs to answer the question - what is Southwest doing to its CFM-56 engines, that numerous other operators are not?