Help B777-300ER
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Join Date: Feb 2001
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Help B777-300ER
What causes more flap track wear and tear?
Extending flaps at limit speeds without speed brakes
OR
Using speed brakes to decelerate as each stage of
flap is extended, i.e. reducing speed to minimum
before extensions using speed brakes.
Extending flaps at limit speeds without speed brakes
OR
Using speed brakes to decelerate as each stage of
flap is extended, i.e. reducing speed to minimum
before extensions using speed brakes.
Join Date: Jan 2008
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Extending the flaps close to the limit speed does cause wear on the flaps, but under normal conditions you should be 10 to 15 kts below each limit speed anyway.............not a problem.
99% of the time I never need speedbrakes to slow while configuring unless caught out, they are not necessary.
CX used to say not to use flap 15 or 20 to slow the aircraft on the GS, they said use the speedbrake instead but that seems to have gone now.
99% of the time I never need speedbrakes to slow while configuring unless caught out, they are not necessary.
CX used to say not to use flap 15 or 20 to slow the aircraft on the GS, they said use the speedbrake instead but that seems to have gone now.
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I just re read you post.
I'm pretty certain Boeing want you to use the speedbrake to slow down and not the flaps.
Thus the CX policy of not using F20 to maintain speed on the GS.
I'm pretty certain Boeing want you to use the speedbrake to slow down and not the flaps.
Thus the CX policy of not using F20 to maintain speed on the GS.
From the B777 FCTM:
"Ideal descent planning is to allow an idle / minimum thrust setting throughout the entire descent sequence and initial stages of flap extension. Progressive flap extension is ideally made when approaching the minimum flap manoeuvre speed. Speed and configuration anticipation will help avoid excessive thrust activity at each intermediate flap manoeuvre speed..."
"...Speed Brakes are the primary means of producing drag, both for profile correction (vertically) and immediate speed reduction.
• Premature flap extension is not to be used to achieve drag. Only in tight / urgent situations combined with full speed brake use, should extension be considered close to flap limit speeds.
• Flap extension is used to facilitate speed reduction either in the normal course of approach speed reduction, or at the request of ATC..."
The Gear Down/F20 technique 2 dots below the GS is a "one-size fits all" profile recommended by Boeing, but it's not always the most efficient way to fly the aircraft. For example, what if you're intercepting the GS at 4,500ft as happens in HKG?
There's nothing wrong, per se, with using a higher flap setting (F15 or 20) if extra drag is required to contain the speed down the GS. However, in that case the preference would be to reduce back to the F15/20 flap manoeuvring speed rather than barreling down the GS at some higher speed. That may not be appropriate if ATC speed control is in force.
"Ideal descent planning is to allow an idle / minimum thrust setting throughout the entire descent sequence and initial stages of flap extension. Progressive flap extension is ideally made when approaching the minimum flap manoeuvre speed. Speed and configuration anticipation will help avoid excessive thrust activity at each intermediate flap manoeuvre speed..."
"...Speed Brakes are the primary means of producing drag, both for profile correction (vertically) and immediate speed reduction.
• Premature flap extension is not to be used to achieve drag. Only in tight / urgent situations combined with full speed brake use, should extension be considered close to flap limit speeds.
• Flap extension is used to facilitate speed reduction either in the normal course of approach speed reduction, or at the request of ATC..."
The Gear Down/F20 technique 2 dots below the GS is a "one-size fits all" profile recommended by Boeing, but it's not always the most efficient way to fly the aircraft. For example, what if you're intercepting the GS at 4,500ft as happens in HKG?
There's nothing wrong, per se, with using a higher flap setting (F15 or 20) if extra drag is required to contain the speed down the GS. However, in that case the preference would be to reduce back to the F15/20 flap manoeuvring speed rather than barreling down the GS at some higher speed. That may not be appropriate if ATC speed control is in force.
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Phlap1,
did someone teach you this during training? If so, I would challenge the guy. Energy wise (certainly during a LDA or CDApproach) it is nonsense.
You could however extend flaps at placard speed, but not only does it increases flap/slat wear it is also risky. You might get overspeed (or at least getting the warning) in case of entering unexpected changes in meteo conditions (T, wind).
Can't add much more than what you can read in previous comments.
Another thing people forget is that speedbrakes/spoilers are only effective at higher speeds ( 240kts and more, the higher the better). When you have problems configuring during an approach and you cannot trade thrust or altitude for speed, the most effective speedkiller would be to use the gear.
did someone teach you this during training? If so, I would challenge the guy. Energy wise (certainly during a LDA or CDApproach) it is nonsense.
You could however extend flaps at placard speed, but not only does it increases flap/slat wear it is also risky. You might get overspeed (or at least getting the warning) in case of entering unexpected changes in meteo conditions (T, wind).
Can't add much more than what you can read in previous comments.
Another thing people forget is that speedbrakes/spoilers are only effective at higher speeds ( 240kts and more, the higher the better). When you have problems configuring during an approach and you cannot trade thrust or altitude for speed, the most effective speedkiller would be to use the gear.
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5star not true on the 777. the speedbrake is very effective maintaining 180 kts or so down the glideslope with flap 5. So effective that you don't even need full speedbrake
.
I know the A330 is totally different, friends that fly it say their speedbrake is totally useless trying to hold speed down the slope with config 2, they need to take the gear.
But the mighty 777 has no probs.
You either take flap 15/20 to hold the speed or use flap 5 and speedbrake. It's up to you, your situation and your company SOP's.
.I know the A330 is totally different, friends that fly it say their speedbrake is totally useless trying to hold speed down the slope with config 2, they need to take the gear.
But the mighty 777 has no probs.
You either take flap 15/20 to hold the speed or use flap 5 and speedbrake. It's up to you, your situation and your company SOP's.
