La Qf Incident [Archive]

Bolty McBolt

29th Mar 2008, 03:25

744ER Max weight RTO at 120+ Kts due to T.O. config warning (Stab position)
Brakes got hot, wheels got hot.
Thermal fuse released the pressure in 4 of the tyres.

No big deal :ok:

displaced gangster

29th Mar 2008, 03:47

'"does anyone one know what caused the aborted takeoff in LA that blow the 4 tyres"

My best guess was that the Captain elected to reject the take-off.:cool:

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Yusef Danet

29th Mar 2008, 04:33

Max weight takeoff with 217 pax??

Short_Circuit

29th Mar 2008, 04:50

does anyone one know what caused the aborted takeoff in LA that blow the 4 tyres

RTO S/W in "RTO" & T/L back to idle during T/O roll.

Will do it every time.

Spanner Turner

29th Mar 2008, 08:05

RTO S/W in "RTO" & T/L back to idle during T/O roll.

Autobrake switch in RTO selection, aircraft has achieved a speed of at least 85 knots and THEN thrust levers are reduced to idle = autobrakes apply at full system pressure

:ok:

VH-XXX

29th Mar 2008, 08:51

Good call Yusef, hard to believe that the 744 ER, repeat ER would be at Max TOW with only that many pax!

twiggs

29th Mar 2008, 09:31

Good call Yusef, hard to believe that the 744 ER, repeat ER would be at Max TOW with only that many pax!

Ever heard of cargo?

Bolty McBolt

29th Mar 2008, 11:24

Ever heard of cargo?

Thank you twiggs I was going to mention it but I thought it to bleedin obvious.

LA often has a huge frieght backlog. It has and often does take months to ship a relief engineers tool box of 60kgs back to base due to no room..

I think you will find the A/C in question was around 400t+, not max but heavy all the same

Keg

29th Mar 2008, 23:41

Good call Yusef, hard to believe that the 744 ER, repeat ER would be at Max TOW with only that many pax!

Of course, silly us. 100 less passengers than full means it may have taken off at 402 tonne instead of 412 unless there was heaps of extra cargo!

An RTO at 402 tonne and 120 knots is still going to cause havoc on the tyres and a couple of plugs melting isn't outside the realms of possibility.

HireTheBetter

30th Mar 2008, 00:53

Can someone with time on type clarify when exactly the take-off config warning would begin to sound?

I would have thought that the take-off config warning horn would sound when the thrust levers are advanced beyond a certain thrust lever angle even prior to reaching the take off thrust position, hence a config warning horn should sound much sooner than then aircraft reaching 120 knots!!!

HTB

maui

30th Mar 2008, 00:57

Bolty

You quote a config warning at a speed of 120k+

Is the Config warn not set to blow as t/l position exceeds a set point?

Or are you suggesting the stab (previously set) had uncommanded movement later in the t/o roll?

Seems to me 120 is a bit late for a config based RTO.

Maui

Short_Circuit

30th Mar 2008, 01:05

Does the word "Defect" come to mind. :}

They can happen at any time! :sad:

Thats why we have engineers. :ok:

RTO S/W in "RTO" & T/L back to idle during T/O roll.

Simplified reply & a slip of the tongue. :uhoh:

Fact is, at 120kts and T/O inhibit doing its thing, then all the bells and

whistles go off telling you not to take off, what are you going to do.

A few seconds to think it over and you are committed to go, like it or not.

Well done skipper.

Bolty McBolt

30th Mar 2008, 01:57

You quote a config warning at a speed of 120k+

Is the Config warn not set to blow as t/l position exceeds a set point?

Maui
I believe you are correct in this.

As short circut mentioned, there was a defect which occured during T/O.
It appears that the stab position was lost and the Config warning sounded.

The question is
The stab has 3 position transducers that feed to their onside FCU. Why does the loss of 1 transducer cause a T/O config warning?
Anybody with access to their training notes?

To those in the know. V1 speed for this type aircaft at this weight, would be?
140kts?

Long Bay Mauler

30th Mar 2008, 01:57

I think that Skipper will get a Xmas card this year!!!!!

Think of all the money he saved by not dumping all that fuel and by not poisoning all the dolphins.............

Geoffo will be grateful:D

Brian Abraham

30th Mar 2008, 02:51

Think of all the money he saved by not dumping all that fuel and by not poisoning all the dolphins.............

Geoffo will be grateful
I'd have thought it more than likely that Geoff would bill the crew for new tires and expenses involved in not running to schedule. :E

Mstr Caution

30th Mar 2008, 03:02

The question is
The stab has 3 position transducers that feed to their onside FCU. Why does the loss of 1 transducer cause a T/O config warning?
Anybody with access to their training notes

On the B744

The Left stab position sensor provides position indication to the left/Cpt's stab trim position.

The right stab position sensor to the right/Fo's stab trim indicator.

Hence you can get a position disagree visible between the two indications

The centre sensor provides data to the takeoff config warning system.

So a loss of centre data or a error from the centre stab positon indicator will cause a takeoff config warning anytime during the roll.

I believe most large commercial jets require the three independant sensors for certification requirements whether boeing or airbus, but someone more knowledgeable may be able to correct me if not the case.

MC:8

lemod

30th Mar 2008, 03:14

HireTheBetter

CONFIG STAB warning occurs when
Stabilizer not within greenband when
aircraft is on the ground, airspeed is less than
V1, three or more Fuel Control switches in
RUN, and engine 2 or 3 thrust in takeoff
range.

Bolty McBolt

30th Mar 2008, 03:18

So a loss of centre data or a error from the centre stab positon indicator will cause a takeoff config warning anytime during the roll.

I am fairly sure the Left transducer system was the offending item

Short_Circuit

30th Mar 2008, 03:20

From memory, don't quote me.

Left stab pos synchro to left indicator

Right stab pos synchro to right indicator

L/R/C stab pos RVDT to L/R/C Flap Cont Units

FCU's passes stab pos to L/R/C FCC.

Each FCC needs independent pos ind for cat III ops.

No idea what feeds T/O Warning other than FCU Stab Pos. My guess all.

maui

30th Mar 2008, 04:17

Incredibly bad luck to have the signal loss/malfunction in that 40 odd seconds between standing the t/l up and 120 knots.

M ;)

Mstr Caution

30th Mar 2008, 04:31

Bolty McBolt & Short Circuit:

My previous comments were from the top of my head !!

I think you may be correct, I think the L & R sensors provide respective Cpt / Fo indications & in the event of either failing the other will provide data on the B744.

As for config warning I think SS is correct, any of the sensors will provide the config warning via the EIU. Older Boeings like 757 I think it's the centre only.

I havent flown a B744 for some time, but is it possible to get an unscheduled trim movement that would cause a takeoff config warning?

MC:8

solocmv

30th Mar 2008, 08:57

The Facts!

Hello All,

This information strait from the radio.

a) It was a mid air drama.
b) The senior pilot noticed that four tyres had blow during the take off run
and decided to stop.
c) All the passengers will be home safley late this afternoon.

I hate it when people just won't listen, all the fact are there. There is no reason for all you cleaver pants to come out of the woodwork.

Cheers,

Solocmv.

Short_Circuit

30th Mar 2008, 10:01

a) It was a mid air drama.
b) The senior pilot noticed that four tyres had blow during the take off run
and decided to stop.
c) All the passengers will be home safley late this afternoon.

a) it was still on the ground. :ugh:
b) the tyres deflated during the stop or after the aircraft stopped. :ugh:
c) all the passengers were safe and went home eventually. :hmm:

What is your point? :confused:

The radio was wrong :eek:

Cartmen

31st Mar 2008, 21:53

Just a point for discussion, the Boeing QRH Non-normal Manouvres section suggests only stopping for a unsafe T/O config warning up to 80kts.

I'm not questioning the Captain/Handling Pilots decision, he was there on the day, but by chance we discussed this scenario on my route check a few weeks ago. The training Capt checking me referred to the QRH and suggested continuing above 80kts.

Short_Circuit

1st Apr 2008, 00:31

It's a long way to fly with no stab trim and fuel burn would
have been a big issue with elevators cranked up all the way home.
And then the holes in the cheese line up, A/P's all fall over and you have
to hold the stick back for 8 hours or divert etc etc.
RTO good choice.