747-200 Flap Ld Relief
Thread Starter
Joined: Sep 2000
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From: NorthTijuana, USA
747-200 Flap Ld Relief
Tell me how FLAP LD RELIEF works.
Flaps 30 you're good at 180 kts, but the LD RELIEF kicks back to Flap 25 if you're above 169 kts. ??? Does it care if you're accelerating or slowing? What's the "logic", and what's the "Q" switch?
Thanks
Flaps 30 you're good at 180 kts, but the LD RELIEF kicks back to Flap 25 if you're above 169 kts. ??? Does it care if you're accelerating or slowing? What's the "logic", and what's the "Q" switch?
Thanks
Usual disclaimers apply!
Joined: Nov 1999
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From: EGGW
The q switch(es) is(are) measuring airspeed. It depends on the airplane line no.
The later -200 a/c had 2 or 3 q switches 1st s/w activated at 25 units repositions to 20 and back to 25 with reducing a/spd. With flap lever at 30 2n/d s/w is activated and the flaps are driven to 25 units or 20 units depending on a/spd., reducing spd repositions flaps back to 25 or 30 units.
The actual a/spds I'd have to go look up!
The later -200 a/c had 2 or 3 q switches 1st s/w activated at 25 units repositions to 20 and back to 25 with reducing a/spd. With flap lever at 30 2n/d s/w is activated and the flaps are driven to 25 units or 20 units depending on a/spd., reducing spd repositions flaps back to 25 or 30 units.
The actual a/spds I'd have to go look up!
Joined: Jun 2001
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From: UTC +8
Typically, Flaps limit speeds are 180kts for Flaps 30, and 205kts for Flaps 25.
The Flap Load Relief System is not active when trailing edge flaps are lowered electrically, and Flaps 30 limit speed would then be 160kts.
The Flap Load Relief System is not active when trailing edge flaps are lowered electrically, and Flaps 30 limit speed would then be 160kts.
Thread Starter
Joined: Sep 2000
Posts: 29
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From: NorthTijuana, USA
I appreciate all the input.
What's not clear is - the flaps 30 limit speed is 180 kts, BUT if you're over 169 kts, the FLAP LD RELIEF kicks the flaps back to Flap 25.
So is the "limit" really 169?
Must be something I'm missing.
What's not clear is - the flaps 30 limit speed is 180 kts, BUT if you're over 169 kts, the FLAP LD RELIEF kicks the flaps back to Flap 25.
So is the "limit" really 169?
Must be something I'm missing.
Joined: Jun 2000
Posts: 476
Likes: 2
Flap load relief light illuminates to indicate the IAS is approaching the limit for the selected flap setting.....common misconception.....it does not indicate the flaps have blown back.....YET!
If F30 is selected the TE flap will blow back to F25 at 183 kts IAS
As the speed reduces the flap will then run automatically to F30 at 165 kts.
If F25 is selected the TE flap will auto run back to F20 at IAS 208 kts and auto extend back to the F25 posn at 191 kts IAS..........
It is written in a confusing manner, if you think of it as I have written above then hopefully all will be clear.......I did say hopefully!
If F30 is selected the TE flap will blow back to F25 at 183 kts IAS
As the speed reduces the flap will then run automatically to F30 at 165 kts.
If F25 is selected the TE flap will auto run back to F20 at IAS 208 kts and auto extend back to the F25 posn at 191 kts IAS..........
It is written in a confusing manner, if you think of it as I have written above then hopefully all will be clear.......I did say hopefully!
fire wall
