B737 QRH Questions
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B737 QRH Questions
i have several, but will do one subject at a time:
QRH
B737:300 CFM56-3 22K
Performance Inflight-General:
Advisory information:
Slush/Standing Water Takeoff:
page PI.20.4
Weight adjustment table: i can understand.
V1(MCG) Limit Weight table: ??? (question 1)
V1 Adjustment (KIAS) ??? (question 2)
1. example:
7000 ft available length: at sea level:
3mm= 59.6
6mm= 62.6
13mm= 66.9
an increase of contamination allows a higher V1(MCG) limit weight on a given runway distance.
2. example:
Weight: 60K at sea level:
3mm= -16
6mm= -10
13mm= 2
also with an increase of contamination, less reduction to V1 and even a increase of 2 knots if it is 13mm!
i could sit here in a dark room and surmize as to the reasons behind this, or simply ask if there is someone out there with some "endorsed" reasons why this is so?
i can think of the increase of slush on runway will increase time to accelerate to any certain V1. but since V1 is a speed (and not a distance) at which one should stop or continue, i can't quite see how the increased slush will cause an increase in V1(MCG) weight or V1 adjustment unless the slush actually helps you to stop.
i first heard that suggestion in Korea, but find it hard to swallow.
then on top of that, do we then go to the slippery runway chart and do some more adjustments, since it should perhaps be considered slippery if there is slush on it, where the V1 adjustment (KIAS) chart makes more since with a decrease of speed with a decrease in braking action.
any help will be greatly appreciated.
more later
QRH
B737:300 CFM56-3 22K
Performance Inflight-General:
Advisory information:
Slush/Standing Water Takeoff:
page PI.20.4
Weight adjustment table: i can understand.
V1(MCG) Limit Weight table: ??? (question 1)
V1 Adjustment (KIAS) ??? (question 2)
1. example:
7000 ft available length: at sea level:
3mm= 59.6
6mm= 62.6
13mm= 66.9
an increase of contamination allows a higher V1(MCG) limit weight on a given runway distance.
2. example:
Weight: 60K at sea level:
3mm= -16
6mm= -10
13mm= 2
also with an increase of contamination, less reduction to V1 and even a increase of 2 knots if it is 13mm!
i could sit here in a dark room and surmize as to the reasons behind this, or simply ask if there is someone out there with some "endorsed" reasons why this is so?
i can think of the increase of slush on runway will increase time to accelerate to any certain V1. but since V1 is a speed (and not a distance) at which one should stop or continue, i can't quite see how the increased slush will cause an increase in V1(MCG) weight or V1 adjustment unless the slush actually helps you to stop.
i first heard that suggestion in Korea, but find it hard to swallow.
then on top of that, do we then go to the slippery runway chart and do some more adjustments, since it should perhaps be considered slippery if there is slush on it, where the V1 adjustment (KIAS) chart makes more since with a decrease of speed with a decrease in braking action.
any help will be greatly appreciated.
more later
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Stator Vane,
I don’t deal with the B737-300, but the general principle of the same for most Boeings. As the depth of the contaminant increases your Accelerate GO weight decreases, but your Accelerate STOP weight increases. The Accelerate STOP is the driving factor, thus you V1=V1MCG weight increases. (Try picturing a wheel ploughing through slush, it builds a wedge in front of the wheel which assists in stopping.)
You don’t go to the slippery runway chart, this is based on a totally different MU factor and generally gives you no stopping ability.
Which system are you following, the FAA or CAA?
Mutt.
I don’t deal with the B737-300, but the general principle of the same for most Boeings. As the depth of the contaminant increases your Accelerate GO weight decreases, but your Accelerate STOP weight increases. The Accelerate STOP is the driving factor, thus you V1=V1MCG weight increases. (Try picturing a wheel ploughing through slush, it builds a wedge in front of the wheel which assists in stopping.)
You don’t go to the slippery runway chart, this is based on a totally different MU factor and generally gives you no stopping ability.
Which system are you following, the FAA or CAA?
Mutt.
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Mutt;
thank you for your reply.
as to your either FAA or CAA question, i just quoted the Boeing QRH that has been issued to me in BRU.
i have heard the wedge statement before, but have never seen any "official" statement to that effect. only word of mouth. whereas if it were a genuine article, it should be printed somewhere with some endorsement on it either FAA, CAA or Boeing or Stella Artois.
whatever gain in stopping ability the slush adds, must have an effect on the time and distance it takes to get to V1 at which point one begins to stop OR go.
and since i have had one bite on the line, i will stretch my welcome and bring up another question:
why the limitation for flaps below 20,000?
is it more CL/CG and airflow and pitch control/maybe stabilizer airflow disturbance at that altitude when slow enough to use flaps, or simply an aerodynamic load stress on the flaps themselves?
thanks again!
thank you for your reply.
as to your either FAA or CAA question, i just quoted the Boeing QRH that has been issued to me in BRU.
i have heard the wedge statement before, but have never seen any "official" statement to that effect. only word of mouth. whereas if it were a genuine article, it should be printed somewhere with some endorsement on it either FAA, CAA or Boeing or Stella Artois.
whatever gain in stopping ability the slush adds, must have an effect on the time and distance it takes to get to V1 at which point one begins to stop OR go.
and since i have had one bite on the line, i will stretch my welcome and bring up another question:
why the limitation for flaps below 20,000?
is it more CL/CG and airflow and pitch control/maybe stabilizer airflow disturbance at that altitude when slow enough to use flaps, or simply an aerodynamic load stress on the flaps themselves?
thanks again!
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Stator Vane,
There are different versions of the Boeing QRH depending on the certification authority, hence my question. As FSB are conducting the training for Korean, I guess that you are operating under the FAA system! The CAA and FAA treat runway contamination differently, I’m only familiar with the FAA system.
The wedge idea is the genuine article, it is explained in detail by Boeing, unfortunately I don’t have their manuals at home with me.
As for the Flaps, check out FAR 25.335 (e)(3) regarding structural loading, the ruling allows for bands between 0-20,000 feet and 20,000 – 50,000 feet. Therefore the flaps are tested in the lower band, the manufacturers then set this as a limitation and wont bother testing above that level due to the costs involved.
Mutt.
There are different versions of the Boeing QRH depending on the certification authority, hence my question. As FSB are conducting the training for Korean, I guess that you are operating under the FAA system! The CAA and FAA treat runway contamination differently, I’m only familiar with the FAA system.
The wedge idea is the genuine article, it is explained in detail by Boeing, unfortunately I don’t have their manuals at home with me.
As for the Flaps, check out FAR 25.335 (e)(3) regarding structural loading, the ruling allows for bands between 0-20,000 feet and 20,000 – 50,000 feet. Therefore the flaps are tested in the lower band, the manufacturers then set this as a limitation and wont bother testing above that level due to the costs involved.
Mutt.
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Mutt;
i checked the part 25 reference you gave and maybe i have a Reader's Digest Condensed Version since i could see no reference to 20,000 feet.
will take the book with me and look for it between BRU/BCN/BRU/FCO today.
thanks again for the response.
still a doubting thomas about the slush on the runway.
i have been web surfing and haven't found anything to clarify that yet.
i checked the part 25 reference you gave and maybe i have a Reader's Digest Condensed Version since i could see no reference to 20,000 feet.
will take the book with me and look for it between BRU/BCN/BRU/FCO today.
thanks again for the response.
still a doubting thomas about the slush on the runway.
i have been web surfing and haven't found anything to clarify that yet.
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Stator Vane,
Firstly the answer to your V-speed question is as follows: Most of the existing wet runway performance adjustments are based on an assumption that the wet braking mu is one half of the dry mu. However at higher weights and speeds the dry mu starts to decrease so the margin between the dry mu and the wet mu (which is established at lower wts and speeds) gets smaller because the wet mu is constant.
Thats straight from Boeing.
As for the flaps, how about For some airplanes there may be an altitude placard for flaps down operation since it may be possible to exceed limit loads when applying maximum roll capability. Tie that up with FAR 25.341 and 335 and hopefully you will get your answer
Mutt
Firstly the answer to your V-speed question is as follows: Most of the existing wet runway performance adjustments are based on an assumption that the wet braking mu is one half of the dry mu. However at higher weights and speeds the dry mu starts to decrease so the margin between the dry mu and the wet mu (which is established at lower wts and speeds) gets smaller because the wet mu is constant.
Thats straight from Boeing.
As for the flaps, how about For some airplanes there may be an altitude placard for flaps down operation since it may be possible to exceed limit loads when applying maximum roll capability. Tie that up with FAR 25.341 and 335 and hopefully you will get your answer
Mutt
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Stator Vane,
The interpretation of the FARs varies according to manufacturer as I discovered this morning. A quick review of some AFM’s shows that Boeing uses 20,000 feet as a flap limit height in the 707/737/747/757/777 (I don’t have data for the 727/767). Airbus uses it with the A300. MDD and Lockheed don’t use it on the DC8/MD90/MD11/L1011.
I believe that the Boeing interpretation uses the Gust Envelope (25.341) to define a cutoff point for their testing envelope. My justification for that statement is as follows:
Positive and negative rough air gusts of 66fps at the speed Vb shall be considered at altitudes between sea level and 20,000 feet. At altitudes above 20,000 feet, the gust velocity may be reduced linearly from 66fps at 20,000 feet to 38fps at 50,000 feet.
Positive and negative rough air gusts of 50fps at the speed Vc shall be considered at altitudes between sea level and 20,000 feet. At altitudes above 20,000 feet, the gust velocity may be reduced linearly from 50fps at 20,000 feet to 25fps at 50,000 feet.
Positive and negative rough air gusts of 25fps at the speed Vd shall be considered at altitudes between sea level and 20,000 feet. At altitudes above 20,000 feet, the gust velocity may be reduced linearly from 25fps at 20,000 feet to 12.5fps at 50,000 feet.
Therefore IMHO this gust envelope combined with a desire to save flight-testing costs leads to the flap limitation.
Mutt.
The interpretation of the FARs varies according to manufacturer as I discovered this morning. A quick review of some AFM’s shows that Boeing uses 20,000 feet as a flap limit height in the 707/737/747/757/777 (I don’t have data for the 727/767). Airbus uses it with the A300. MDD and Lockheed don’t use it on the DC8/MD90/MD11/L1011.
I believe that the Boeing interpretation uses the Gust Envelope (25.341) to define a cutoff point for their testing envelope. My justification for that statement is as follows:
Positive and negative rough air gusts of 66fps at the speed Vb shall be considered at altitudes between sea level and 20,000 feet. At altitudes above 20,000 feet, the gust velocity may be reduced linearly from 66fps at 20,000 feet to 38fps at 50,000 feet.
Positive and negative rough air gusts of 50fps at the speed Vc shall be considered at altitudes between sea level and 20,000 feet. At altitudes above 20,000 feet, the gust velocity may be reduced linearly from 50fps at 20,000 feet to 25fps at 50,000 feet.
Positive and negative rough air gusts of 25fps at the speed Vd shall be considered at altitudes between sea level and 20,000 feet. At altitudes above 20,000 feet, the gust velocity may be reduced linearly from 25fps at 20,000 feet to 12.5fps at 50,000 feet.
Therefore IMHO this gust envelope combined with a desire to save flight-testing costs leads to the flap limitation.
Mutt.
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Stator Vane,
The idea of the ploughing effect isn’t just word of mouth, Boeing explains exactly how they calculate contaminated runway data, unfortunately it isn’t information that is normally given to pilots.
The technical term for it is “Displacement Drag” which together with “Impingement Drag” forms your Slush Drag coefficient for the airplanes specific gear arrangement. I wish that there was an easier way for me to explain this, but I cant find one, so here goes……
Your acceleration with slush / standing water is:
a= g/w [Thrust – Drag – Friction – Fslush]
Fslush = 1/2Ρ Vg2 Cdslush Atire where
P = Slush density equal to a specific gravity of 0.85
Vg = Ground speed feet per second
Cdslush = Displacement Drag and Impingement Drag
Atire = (Σb_main + Σb_nose) x slush depth (Σb = avg tire width)
So the depth of slush has a direct impact on your acceleration, the opposite is true for stopping.
This is taken from a 42 page Boeing presentation on the subject of Contaminated Runways. If you want more information, you can either ask Boeing for it or send me your snail mail address.
Rgds.
Mutt
[email protected]
The idea of the ploughing effect isn’t just word of mouth, Boeing explains exactly how they calculate contaminated runway data, unfortunately it isn’t information that is normally given to pilots.
The technical term for it is “Displacement Drag” which together with “Impingement Drag” forms your Slush Drag coefficient for the airplanes specific gear arrangement. I wish that there was an easier way for me to explain this, but I cant find one, so here goes……
Your acceleration with slush / standing water is:
a= g/w [Thrust – Drag – Friction – Fslush]
Fslush = 1/2Ρ Vg2 Cdslush Atire where
P = Slush density equal to a specific gravity of 0.85
Vg = Ground speed feet per second
Cdslush = Displacement Drag and Impingement Drag
Atire = (Σb_main + Σb_nose) x slush depth (Σb = avg tire width)
So the depth of slush has a direct impact on your acceleration, the opposite is true for stopping.
This is taken from a 42 page Boeing presentation on the subject of Contaminated Runways. If you want more information, you can either ask Boeing for it or send me your snail mail address.
Rgds.
Mutt
[email protected]
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Mutt,
Is it available as a PDF or in any other e-format? Alternatively, do you have a Boeing contact, please?
------------------
Stay Alive,
[email protected]
Is it available as a PDF or in any other e-format? Alternatively, do you have a Boeing contact, please?
------------------
Stay Alive,
[email protected]
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Mutt;
due to limited resources and basic abilities, all i have found thus far was a quote in "handling the big jets" by Davies.
on page 194 i found a comforting line:
"the determination of slush effect on aircraft performance has been done mostly under simulated conditions... naturally there are many problems which are not readily solved and a pilot may well be forgiven if he questions the accuracy of slush accountability."
i am not alone it seems.
sounds a bit similar to the thread on reducing thrust to the limit based on text book figures.
thanks again for all your time and efforts.
my email is: [email protected]
due to limited resources and basic abilities, all i have found thus far was a quote in "handling the big jets" by Davies.
on page 194 i found a comforting line:
"the determination of slush effect on aircraft performance has been done mostly under simulated conditions... naturally there are many problems which are not readily solved and a pilot may well be forgiven if he questions the accuracy of slush accountability."
i am not alone it seems.
sounds a bit similar to the thread on reducing thrust to the limit based on text book figures.
thanks again for all your time and efforts.
my email is: [email protected]
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4dogs,
You could ask your local Boeing rep to dig you up a copy of the Flight Operations Performance Engineers - Operations Course Notes.
Alternatively, email me in around 10 days time when I have finished my days off and I will snail-mail a copy to you.
Stator Vane.
Flying the Bigjets is correct, the haven’t flight tested your 737 under these conditions. NASA carried out tests in the 1960’s using a Convair 880, the results of these tests have formed the basis for calculating the effects of contaminants. Unfortunately it is one of those things that are never really explained to people.
Safe flying.
Mutt
[email protected]
You could ask your local Boeing rep to dig you up a copy of the Flight Operations Performance Engineers - Operations Course Notes.
Alternatively, email me in around 10 days time when I have finished my days off and I will snail-mail a copy to you.
Stator Vane.
Flying the Bigjets is correct, the haven’t flight tested your 737 under these conditions. NASA carried out tests in the 1960’s using a Convair 880, the results of these tests have formed the basis for calculating the effects of contaminants. Unfortunately it is one of those things that are never really explained to people.
Safe flying.
Mutt
[email protected]
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Quote from
Boeing 727 Flight Crew Training Manual
Maneuvers - Cruise - Airwork
Flap Usage
Flaps are intended for use during takeoff, traffic pattern work and landing. Thus, flap systems are designed to withstand limited attitude and airspeeds and limited time exposure within these flight regimes. Use of flaps during enroute descents is not recommended and can result in operational problems and higher maintenance costs.
Flaps placard speeds at high altitudes have not been verified or FAA approved. The flaps are designed to accommodate the FAR maneuver requirement of 2.0 g's or a derived gust velocity of 25 feet per second at flap placard speed. These are for limited loads and ultimate loads are 50% higher. Thus with flaps extended the airplane has less tolerance to gust and maneuver accelerations than in the clean configuration.
At higher altitudes (above 20,000 feet) where aerodynamic damping diminishes, lateral control capability with the outboard ailerons active (flaps down), results in excessive ro]] rates.
Because of the above, flap extension is limited to altitudes below 20,000 feet.
- end quote
BTW: I don't know if they have covered the subject(s) but do take a look at Boeings Aero magazine on http://www.boeing.com/commercial/aeromagazine/
[This message has been edited by dusk2dawn (edited 30 June 2001).]
Boeing 727 Flight Crew Training Manual
Maneuvers - Cruise - Airwork
Flap Usage
Flaps are intended for use during takeoff, traffic pattern work and landing. Thus, flap systems are designed to withstand limited attitude and airspeeds and limited time exposure within these flight regimes. Use of flaps during enroute descents is not recommended and can result in operational problems and higher maintenance costs.
Flaps placard speeds at high altitudes have not been verified or FAA approved. The flaps are designed to accommodate the FAR maneuver requirement of 2.0 g's or a derived gust velocity of 25 feet per second at flap placard speed. These are for limited loads and ultimate loads are 50% higher. Thus with flaps extended the airplane has less tolerance to gust and maneuver accelerations than in the clean configuration.
At higher altitudes (above 20,000 feet) where aerodynamic damping diminishes, lateral control capability with the outboard ailerons active (flaps down), results in excessive ro]] rates.
Because of the above, flap extension is limited to altitudes below 20,000 feet.
- end quote
BTW: I don't know if they have covered the subject(s) but do take a look at Boeings Aero magazine on http://www.boeing.com/commercial/aeromagazine/
[This message has been edited by dusk2dawn (edited 30 June 2001).]
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dusk2dawn:
thank you for your information.
ends up being one of those "just because!" things.
mutt:
i also would like a cc of that doc if possible: [email protected].
i have tried to find such info on web but can't seem to have much success.
why is it so much easier to stumble on pictures of girls than this need to know information?
thanks again all;
thank you for your information.
ends up being one of those "just because!" things.
mutt:
i also would like a cc of that doc if possible: [email protected].
i have tried to find such info on web but can't seem to have much success.
why is it so much easier to stumble on pictures of girls than this need to know information?
thanks again all;
Guest
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have you been watching the changes in the QRH in the Uncommanded Rudder and Uncommanded Yaw or Roll sections?
fortunately i have not encountered that.
still the way it is now, i cannot see their point in having the two different check lists as they are now except it be for some legal "cover OUR ass" needs on Boeing's part.
should be memory item!?
can you imagine the real event?
FO: "Captain, the aircraft is rolling past 60 degrees of bank! are you doing that on purpose?"
CP: "No, i was looking in my flight bag for my sunglasses."
FO: "did you find them?"
CP: "yes, but i can't reach them. they're laying on the overhead panel!!??"
CP: "let's have the 'Uncommanded sunglasses on the overhead panel' checklist please"
FO: "i'd love to sir, but i can't reach the QRH! it just went under my rudder pedals"
CP: "does the Back Course function work for the Localizer if the aircraft is inverted?"
FO: "don't know. haven't done that in the sim yet."
CP: "better get the 'after crashing into the trees' checklist ready. we might need it."
FO: "better call crew planning too!"
fortunately i have not encountered that.
still the way it is now, i cannot see their point in having the two different check lists as they are now except it be for some legal "cover OUR ass" needs on Boeing's part.
should be memory item!?
can you imagine the real event?
FO: "Captain, the aircraft is rolling past 60 degrees of bank! are you doing that on purpose?"
CP: "No, i was looking in my flight bag for my sunglasses."
FO: "did you find them?"
CP: "yes, but i can't reach them. they're laying on the overhead panel!!??"
CP: "let's have the 'Uncommanded sunglasses on the overhead panel' checklist please"
FO: "i'd love to sir, but i can't reach the QRH! it just went under my rudder pedals"
CP: "does the Back Course function work for the Localizer if the aircraft is inverted?"
FO: "don't know. haven't done that in the sim yet."
CP: "better get the 'after crashing into the trees' checklist ready. we might need it."
FO: "better call crew planning too!"
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Its amazing what you find when you aren’t looking for it, this is taken from a Boeing Airliner magazine:
Several operators have asked Boeing why the Airplane Flight Manual has a limitation restricting the use of flaps above 20,000 feet. The reason for the limitation is simple; Boeing does not demonstrate or test (and therefore does not certify) airplanes for operations with flaps extended above 20,000 feet.
There is no Boeing procedure which requires the use of flaps above 20,000 feet. Since flaps are intended to be used during the takeoff and approach/land phases of flight, and since Boeing is not aware of any airports where operation would require the use of flaps above 20,000 feet, there is no need to certify the airplane in this configuration
Now if only I had found that 2 weeks ago!!!!!!!
Mutt.
Several operators have asked Boeing why the Airplane Flight Manual has a limitation restricting the use of flaps above 20,000 feet. The reason for the limitation is simple; Boeing does not demonstrate or test (and therefore does not certify) airplanes for operations with flaps extended above 20,000 feet.
There is no Boeing procedure which requires the use of flaps above 20,000 feet. Since flaps are intended to be used during the takeoff and approach/land phases of flight, and since Boeing is not aware of any airports where operation would require the use of flaps above 20,000 feet, there is no need to certify the airplane in this configuration
Now if only I had found that 2 weeks ago!!!!!!!
Mutt.
