B737 Classic - Exceedance of LED Extension speed
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B737 Classic - Exceedance of LED Extension speed
To my knowledge there is no specific mention in Vol 1 or 2 of a maximum speed with leading edge devices extended. It is alluded to in the QRH for Alternate Flap selection where arming of the Alternate Flaps Master Switch takes place at a max speed of 230 knots. However, in that excellent publication, 737 Cockpit Companion, at page 9 it states max speed LED extended 230 knots.
In the real aircraft and also for the 737-200, if the speed exceeded 230 knots during acceleration during flap retraction to flaps up, it was not unusual to see the LED amber light stay on because the LED were prevented from complete retraction due excessive speed. The fix of course was to reduce speed to below 230 knots and the LED would come fully in and the LED light would extinguish. Has anyone experienced this event in normal operations?
In one particular 737-300 simulator I operate, the events described above are well demonstrated along with the low frequency vibration that can warn the pilot of an LED still hanging out due excess speed. However on another simulator-a 737-400 type, it doesn't matter how fast you go - 260-270 knots or more, the LED will always retract normally - in other words excess speed does not affect LED retraction in that particular Level 5 simulator.
My understanding from the technicians that run the -400 simulator is as there is no published limit in Vol1 or Vol 2, for LED extension the LED simulator software ensures that the LED will always retract fully in spite of high speed (above 230 knots for instance). Does this mean that the fidelity of the -400 simulator is not true compared with the same event in the 737-300 simulator of another operator?
If the speed exceeds 230 knots in the real aircraft while the LED are in the process of retracting, I have observed that the LED will stay stuck out until the speed is reduced. That said, would it be correct to say that 737-400 simulator should correctly reflect the aircraft experience?
Otherwise I would have thought that crews trained on the 737-400 simulator would assume that there is no problem with high speed LED retraction as the LED will always come in as normal?
In the real aircraft and also for the 737-200, if the speed exceeded 230 knots during acceleration during flap retraction to flaps up, it was not unusual to see the LED amber light stay on because the LED were prevented from complete retraction due excessive speed. The fix of course was to reduce speed to below 230 knots and the LED would come fully in and the LED light would extinguish. Has anyone experienced this event in normal operations?
In one particular 737-300 simulator I operate, the events described above are well demonstrated along with the low frequency vibration that can warn the pilot of an LED still hanging out due excess speed. However on another simulator-a 737-400 type, it doesn't matter how fast you go - 260-270 knots or more, the LED will always retract normally - in other words excess speed does not affect LED retraction in that particular Level 5 simulator.
My understanding from the technicians that run the -400 simulator is as there is no published limit in Vol1 or Vol 2, for LED extension the LED simulator software ensures that the LED will always retract fully in spite of high speed (above 230 knots for instance). Does this mean that the fidelity of the -400 simulator is not true compared with the same event in the 737-300 simulator of another operator?
If the speed exceeds 230 knots in the real aircraft while the LED are in the process of retracting, I have observed that the LED will stay stuck out until the speed is reduced. That said, would it be correct to say that 737-400 simulator should correctly reflect the aircraft experience?
Otherwise I would have thought that crews trained on the 737-400 simulator would assume that there is no problem with high speed LED retraction as the LED will always come in as normal?
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Unfortunately we experienced what you described in your first two paragraphs out of Gatwick about 15 years ago in a -200. Exactly as described. When the speed was reduced below 230, they retracted with a what seemed like a bit of a bang. We discontinued the flight and landed back doing a flapless. No damage apart from to pride.
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Rainboe. Interesting one, that. If the LED did not initially retract because you were too fast, but they did finally retract when you reduced below 230 or thereabouts, would it have been necessary to do a flapless, when the LED had already returned to normal operation? On the other hand perhaps it was a prudent decision to be balanced against high touch-down speeds and increased risk of tyre failure or hot brakes.
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Their logic probably went to that a bang isn't very normal is it, if the LED's still should be operating normally.
I suppose you could take the Flaps to 1 and see what happens, you can also use a 10000' runway and the brakes will be no issue
I suppose you could take the Flaps to 1 and see what happens, you can also use a 10000' runway and the brakes will be no issue
