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B737NG engine fire just below V1

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B737NG engine fire just below V1

Old 28th Jun 2007, 01:07
  #81 (permalink)  
 
Join Date: Aug 1999
Location: Ft Lauderdale, Fl
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Thumbs up Hello

You said just below V1, well I would continue.

I havent read most of the responses on this thread but will.

As for the current thinking on aborts/stops. The TO should be divided into 2 regimes, low speed and high speed. The deciding factor is 100 knots, this is now industry standard is being taught by Airbus and Boeing.

Most of the overuns have been with good engines operating and most fire warnings are for a BLEED LEAK which can be best handled in the air rather than off the runway.

For me, I dont abort unless its for an engine failure before V1.
Reel Marine is offline  
Old 28th Jun 2007, 01:55
  #82 (permalink)  
 
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How can you be sure that your assumptions of the condition of the runway won't allow for a succesful aborted takeoff before V1?
Can you make that decision in 2 seconds?
Fire warning - one, two - did you continue or reject?

Do you then brief it in your take off emergency briefing or is it something you decide if it happens, that you will continue before V1?

How do you know how bad the fire is to the engine and that the engine is not severely damaged by the outburst of a fire and then producing no thrust?

What is your new decision speed if you don't want to use the one calculated for you by the fmc, V1-1kts V1-2kts V1-3kts V1-10 kts V1-20 kts?

Where does your SOP allow you to disregard calculated FMC speeds and use one made up in your head?
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Old 28th Jun 2007, 04:22
  #83 (permalink)  
 
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Arrow

Guest27, let's suppose that you decide to abort the takeoff near V1, as the book states you can.

If your V1 speed is 156 knots with reduced flaps and you clearly see the end of the runway as you are near this speed as you abort the takeoff, there is NO guarantee, even if done perfectly, that your plane will stop on the runway, no matter what book theory claims. Yesterday, our flaps 5, V1 was 156 with a V2 at 166 knots. By the way, a mechanic told us that this airline no longer changes brake shoes when you feel an irritating chatter coming to a stop at low taxi speeds and write it up. They merely bleed air from the lines, somewhere near the anti-skid valves. Thi$ certainly has no effect on the operation.... This is just one component. Some of our mechanics have been told by a supervisor to avoid unnecessary line checks, because they might find a problem. $$

The people who approve and design the FAR$ often have never flown a high-performance aircraft, or not for many years. They are quite safe behind their desks with a view of a busy boulevard in Washington, DC, just as safe as your company Dispatchers.

In the US, an abort assumes that we can Begin the maneuver by V1 and still stop, not finish it by V1. Because of an inherent contradiction in the FARs and the fact that certification test aborts are done by well-trained test pilots in a brand-new plane and on a perfectly dry runway, lots of people might die if you abort at V1.

The engines, whether tail-mounted or wing-, will not normally let a real fire go from the engine into the fuselage or wings.
Do you want to be willing to hurt/kill some children riding in the back when there could be just a bleed valve etc leaking hot air and the plane will probably rotate and climb at V2+10 with no problem, or after a warning which results when an MEL Dispatch Deviation Guide (DDG) procedure was not done correctly (maybe a computer fault)? How many years have your mechanics been repairing your aircraft?

Maintenance 'out$ourcing'?

Last edited by Ignition Override; 28th Jun 2007 at 04:37.
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Old 28th Jun 2007, 06:07
  #84 (permalink)  
 
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Originally Posted by Old Smokey
Actually, it would surprise me if the B717 did not have an aural fire warning inhibit after V1 (or Vr for non-FMC inserted V speeds aircraft via Air Ground sensing), ....
....On post #44 in this thread I responded to FatDog that I was referring entirely to the pre-V1 case, as that is what this thread is about.
Oops, missed post #44. My apologies for making a redundant post.

Side issue, but the inhibit in question applies to V1 in all cases, whether a "magenta" or "white", that is, FMC calculated, or pilot entered.
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Old 28th Jun 2007, 10:00
  #85 (permalink)  
 
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How can you be sure that your assumptions of the condition of the runway won't allow for a successful aborted takeoff before V1?
I can't, that's the whole point. I can't tell for sure if I'll stay on the runway or run off the end. I know for a fact that the odds are stacked against me.
Do you then brief it in your take off emergency briefing or is it something you decide if it happens, that you will continue before V1?
Yes, it will be in my briefing. V1 minus 5 and we go
How do you know how bad the fire is to the engine and that the engine is not severely damaged by the outburst of a fire and then producing no thrust?
To the first part, I don't know. The rest will show up on the engine instruments.
Where does your SOP allow you to disregard calculated FMC speeds and use one made up in your head?
My SOP allows me to deviate from any published procedures in the interest of safety. I have to justify it later. The fact is, I don't know if I can stop. I know I can continue (performance wise). If I GO and land safe, all is well. If I stop and stay on the runway, all is well. If I stop and run off the end, they still can't touch me since I've followed my SOP to the letter, but to me it's not the smartest or safest course of action (given the circumstances).
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Old 28th Jun 2007, 10:57
  #86 (permalink)  
Warning Toxic!
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I know if I was sitting at the back as a passenger on a take-off from as limiting a contaminated runway as you like, if the choice is available to the pilot, I would like him to stop and take my chances with an over-run than struggle into the air on one with an active fire warning going. Period. You can produce all the scenarios you like about how difficult it is, but it has been factored into the calcs and if stopping at V1 is open to you and you're burning, you're a darn fool not to! The firewire is pretty foolproof and failsafe- if it is blowing the warning, you must assume there is a genuine problem.

Realistically, on a twin, your acceleration is bewildering. Speed is building up so fast that at a few knots below V1, you don't have thinking time. You must go into automatic and not take a shoot-from-the-hip decision trying to factor in runway state/length/wind/slope. It's just that sort of decision making process that gets you into big trouble! Then you must imagine sitting in a witness box at a Coroners Court explaining your decision to go against rules and regulations.
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Old 28th Jun 2007, 12:37
  #87 (permalink)  
 
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The people who approve and design the FAR$ often have never flown a high-performance aircraft, or not for many years. They are quite safe behind their desks with a view of a busy boulevard in Washington, DC, just as safe as your company Dispatchers.
I don't see that the FARS have anything to do with this.

The decision is a pilot decision.

the go-no-go recommendations are based on statistics (100kts and greater) and not about V1, a pilots decision simply considers V1
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Old 30th Jun 2007, 17:37
  #88 (permalink)  
 
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By the way...

The Dornier 328 does have an inhibit function on its fire warning tone. (It uses a tone generator rather than an actual bell.) You get the Master Warning and the Fire Warning lights but the tone doesn't sound until you have passed a certain time/height boundary. (I'm not currently flying the type so that I cannot tell you the exact values but there is probably a 328 pilot here who can say what they are.)

This particular set-up could trigger an abort with a warning below 80 knots but a go with a warning between 80 knots and V1 if it was not noticed as a fire warning, since part of the usual brief is something like ".... abort for any red warning below 80 knots, abort for fire, blocked runway or loss of control between 80 and V1..."

I would have thought that if you had briefed for an abort for a fire below V1 then you should follow the brief and abort. Otherwise wouldn't you simply want to nominate a different V1 to suit the circumstances? The ideal is that a chosen V1 should allow a safe abort, isn't it? If one briefs one way and then acts in another way, well, that sort of makes a nonsense of doing the brief in the first place. Think of the poor old FO who would have to think, "This is Captain X who will probably want to abort," or else, "This is Captain Y who will probably want to go," and then hope he guesses right on the day. You could call that bad CRM!
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