Boeing amend 737 de-icing procedures & propose aircraft mods after near-stall inciden
Thread Starter
Join Date: Apr 2002
Location: FUBAR
Posts: 3,348
Likes: 0
Received 0 Likes
on
0 Posts
Hey Dude, don't know which procedures your " independant preferred receiver" of you the "independant service provider" (I hesitate to use the word employer) is using but I have never seen any of yours messing with flaps when they have been de-icing around me, and certainly the only mention of flaps we have is to consider large accumulations of slush/crud when deciding to retract (or not) after landing, and to delay deploying them until after de-icing (or approaching departure runway if taxi-way severely contaminated.)
Cycling horizontal stab is another thing, but it seems with the new procedure (which we have adopted) that will now be a thing of the past.
Cycling horizontal stab is another thing, but it seems with the new procedure (which we have adopted) that will now be a thing of the past.
Join Date: Jan 2000
Location: FL410
Posts: 860
Likes: 0
Received 0 Likes
on
0 Posts
Cycling of flaps is only achieved in Freezing conditions (<+3C), not Icing conditions (<+10C), when deicing has occurred, etc... Only with a set of worst criteria.
It is to ensure freedom of movement of controls and high lift devices and so on, secondly this also allows a flight control check if a jet has been parked for several days in sub temperatures on first flight back into service (we all seen the jets parked up and rotated throughout winter use).
Now I would like to suggest that any such check should be done only immediately prior to departure, such as at a holding point, therefore not halving the holdover time by up to 50% as riven by independent research. Unfortunately this seems not the case in practise.
It is to ensure freedom of movement of controls and high lift devices and so on, secondly this also allows a flight control check if a jet has been parked for several days in sub temperatures on first flight back into service (we all seen the jets parked up and rotated throughout winter use).
Now I would like to suggest that any such check should be done only immediately prior to departure, such as at a holding point, therefore not halving the holdover time by up to 50% as riven by independent research. Unfortunately this seems not the case in practise.
Join Date: Jul 2010
Location: EU
Posts: 42
Likes: 0
Received 0 Likes
on
0 Posts
Recycling of flaps is definitely an operator specific item.
My first 737 company never mentioned it.
Second 737 company said it should be done if temp less than -18C.
Third 737 company has it in adverse weather supp, but no mention of a temp.
My first 737 company never mentioned it.
Second 737 company said it should be done if temp less than -18C.
Third 737 company has it in adverse weather supp, but no mention of a temp.
Join Date: Sep 2013
Location: UK
Posts: 730
Likes: 0
Received 0 Likes
on
0 Posts
It used to be 737 post de-icing procedure to cycle the ailerons and elevators to full deflection in both directions in the before take off checks to drain de-icing fluid out of the balance cavities until just a few years ago, when the procedure was removed because the drain holes were drilled larger. I wonder if that old practice also had an unknown benefit of moving any slush off the control mechanisms, so masking the issue and it only coming to light recently. I still cycle the controls three times anyway - it might be un-necessary, but it costs me nothing.
Join Date: Dec 2012
Location: Gatwick
Posts: 452
Likes: 0
Received 0 Likes
on
0 Posts
Snow and frost tends to form on the upper surfaces, underwing frost is normally down to cold soak fuel freezing the moisture in the air it is in contact with, so highly unlikely for any to form on underneath of the stab? just saying....
Join Date: Sep 2013
Location: UK
Posts: 730
Likes: 0
Received 0 Likes
on
0 Posts
I thought we were discussing ice accumulation on the PCUs, not stab frost. The three cycles of the elevator was for clearing fluid that had got inside the elevator balance cavities, nothing to do with the stab.
As for flap cycling, it appeared on my company's Freezing Conditions before take off checklist a year or so ago. Flap selection is deferred until entering the runway, but I can't remember off hand when the cycle is required, before taxy or immediately before flap selection. I think it's the latter, which would be more prudent.
As for flap cycling, it appeared on my company's Freezing Conditions before take off checklist a year or so ago. Flap selection is deferred until entering the runway, but I can't remember off hand when the cycle is required, before taxy or immediately before flap selection. I think it's the latter, which would be more prudent.
Join Date: Apr 2013
Location: up front on the right
Posts: 39
Likes: 0
Received 0 Likes
on
0 Posts
Supp Proc
Boeing 737-800 FCOM 1 Supplementary Procedures SP 16.6
Before Taxi
Flaps ............................................................ .................Check F/O
Move the flaps from Flaps up to Flaps 40 back to Flaps up (i.e., full
travel) to ensure freedom of movement.
If taxi route is through ice, snow, slush or standing water in low
temperatures or if precipitation is falling with temperatures below
freezing, taxi out with the flaps up. Taxiing with the flaps extended
subjects the flaps and flap drives to contamination. Leading edge devices
are also susceptible to slush accumulations.
Call “FLAPS ___” as needed. C
Flap lever ................................................ Set flaps, as needed F/O
Before Taxi
Flaps ............................................................ .................Check F/O
Move the flaps from Flaps up to Flaps 40 back to Flaps up (i.e., full
travel) to ensure freedom of movement.
If taxi route is through ice, snow, slush or standing water in low
temperatures or if precipitation is falling with temperatures below
freezing, taxi out with the flaps up. Taxiing with the flaps extended
subjects the flaps and flap drives to contamination. Leading edge devices
are also susceptible to slush accumulations.
Call “FLAPS ___” as needed. C
Flap lever ................................................ Set flaps, as needed F/O
Join Date: Jan 2000
Location: FL410
Posts: 860
Likes: 0
Received 0 Likes
on
0 Posts
Adverse Weather Conditions
Before Taxi Procedure
Do the normal Before Taxi Procedure with the following modifications:
GENERATOR 1 and 2 switches ........................................................ ON
Normally the IDG’s will stabilize within one minute, although due to cold oil, up to five minutes may be needed to produce steady power.
Flight controls ............................................................ .................... Check
An increase in control forces can be expected at low temperatures.
In freezing conditions:
CAUTION: The flap position indicator and the leading edge devices annunciator panel should be closely observed for positive movement. If the flaps should stop, the flap lever should be placed immediately in the same position as indicated.
Flaps ............................................................ .............................. Check
Move the flaps from Flaps Up to Flaps 40 back to Flaps up (i.e., full travel) to ensure freedom of movement.
If remote de-icing is planned or if the taxi route is through slush or standing water in freezing conditions, or if precipitation is falling in freezing conditions, taxi out with the flaps up. Taxiing with the flaps extended subjects the flaps and flap drives to contamination. Leading edge devices are also susceptible to slush accumulations.
Flap lever ................................................. Set takeoff flaps, as needed
Before Taxi Procedure
Do the normal Before Taxi Procedure with the following modifications:
GENERATOR 1 and 2 switches ........................................................ ON
Normally the IDG’s will stabilize within one minute, although due to cold oil, up to five minutes may be needed to produce steady power.
Flight controls ............................................................ .................... Check
An increase in control forces can be expected at low temperatures.
In freezing conditions:
CAUTION: The flap position indicator and the leading edge devices annunciator panel should be closely observed for positive movement. If the flaps should stop, the flap lever should be placed immediately in the same position as indicated.
Flaps ............................................................ .............................. Check
Move the flaps from Flaps Up to Flaps 40 back to Flaps up (i.e., full travel) to ensure freedom of movement.
If remote de-icing is planned or if the taxi route is through slush or standing water in freezing conditions, or if precipitation is falling in freezing conditions, taxi out with the flaps up. Taxiing with the flaps extended subjects the flaps and flap drives to contamination. Leading edge devices are also susceptible to slush accumulations.
Flap lever ................................................. Set takeoff flaps, as needed
Join Date: Aug 2000
Posts: 1,501
Likes: 0
Received 0 Likes
on
0 Posts
None of those procedures are in our manuals, but operators may get Boeing to include operator spesific procedures in the FCOM, but Boeing do not take any responsibilty for those procedures.
Join Date: Apr 2013
Location: up front on the right
Posts: 39
Likes: 0
Received 0 Likes
on
0 Posts
That was actually from the Generic Boeing Manual. It may be the other way around though - some companies have certain procedures scrapped or modified based on their operational needs.
Join Date: Jun 2000
Location: last time I looked I was still here.
Posts: 4,507
Likes: 0
Received 0 Likes
on
0 Posts
Before taxi.
Flaps ............................................................ .............................. Check
Move the flaps from Flaps Up to Flaps 40 back to Flaps up (i.e., full travel) to ensure freedom of movement.
If remote de-icing is planned or if the taxi route is through slush or standing water in freezing conditions, or if precipitation is falling in freezing conditions, taxi out with the flaps up. Taxiing with the flaps extended subjects the flaps and flap drives to contamination. Leading edge devices are also susceptible to slush accumulations.
This always gave me trouble. My limited common sense wanted to adjust this; but had some resistance from F/O's & LTC's. The above statement is what was on my checklist. It was snowing at the gate, but de-icing was quite a distance from the apron; thus we needed to taxi a long way before being sprayed. I suggested we taxi out with flaps up and after de-icing do the F40 exercise thingy. Oh no. It was met with horror. I surmised that to open the flaps in snow, and then close then again, could trap snow in the gaps which would be compressed and not be influenced by the de-icing fluid. It was insisted that we exercise the flaps before taxi, de-ice and then taxi with flaps up to the holding point.
Opinions please. Am I mad, or what?
Flaps ............................................................ .............................. Check
Move the flaps from Flaps Up to Flaps 40 back to Flaps up (i.e., full travel) to ensure freedom of movement.
If remote de-icing is planned or if the taxi route is through slush or standing water in freezing conditions, or if precipitation is falling in freezing conditions, taxi out with the flaps up. Taxiing with the flaps extended subjects the flaps and flap drives to contamination. Leading edge devices are also susceptible to slush accumulations.
This always gave me trouble. My limited common sense wanted to adjust this; but had some resistance from F/O's & LTC's. The above statement is what was on my checklist. It was snowing at the gate, but de-icing was quite a distance from the apron; thus we needed to taxi a long way before being sprayed. I suggested we taxi out with flaps up and after de-icing do the F40 exercise thingy. Oh no. It was met with horror. I surmised that to open the flaps in snow, and then close then again, could trap snow in the gaps which would be compressed and not be influenced by the de-icing fluid. It was insisted that we exercise the flaps before taxi, de-ice and then taxi with flaps up to the holding point.
Opinions please. Am I mad, or what?
Join Date: Sep 2013
Location: UK
Posts: 730
Likes: 0
Received 0 Likes
on
0 Posts
We are deiced flaps up (unless they were contaminated on previous ldg, in which case they're left at 15 until deiced). I just couldn't remember whether the C/L said to do the run check before taxi or at the hold point immediately before selecting TO flap, likewise the controls check. I'll be delaying the checks to the hold point so that the list can be done in order but such that I'm not shedding the diecing fluid by sloping the controls until the last safe moment...
If remote deicing, then I'd run the before taxi c/l after deicing, before the second taxi. Keeps everyone happy!
If remote deicing, then I'd run the before taxi c/l after deicing, before the second taxi. Keeps everyone happy!
Join Date: Sep 2013
Location: UK
Posts: 730
Likes: 0
Received 0 Likes
on
0 Posts
Capt, you're sadly right. Too many trainers force line shags to strictly follow unrealistically literal (mis)interpretations of SOPs, which themselves are oft flawed or poorly written.
Join Date: Aug 2000
Posts: 1,501
Likes: 0
Received 0 Likes
on
0 Posts
Not mad, but smart! I remember this procedure was in our books, but was only to be done in extremly cold wx, ie -30 celsius-ish. Same with the nose wheel steering left right, and idle for several minutes to let the IDGs stabilize. And having the ground crew heating the engines before starting.
I believe the full flap exercise is to make sure the flaps are not frozen in any way, but for that very reason I would deice before trying to move them.
We taxi to and from deice with flaps up, and only set take off flaps right before lining up. This way we don't expose the untreated areas to icing conditions before we take off.
I believe the full flap exercise is to make sure the flaps are not frozen in any way, but for that very reason I would deice before trying to move them.
We taxi to and from deice with flaps up, and only set take off flaps right before lining up. This way we don't expose the untreated areas to icing conditions before we take off.
