Text 9309, 113 rader
Skriven 2013-07-19 17:10:48 av Roy Witt (1:387/22)
   Kommentar till text 9308 av Torbjorn Mohn (2:211/37)
Ärende: De Nar
==============
Torbjorn Mohn wrote to Roy Witt:

 >>>> Note that flight BA38 was a 737, not a 777. You lose, again.

 >>> Oops...... :
 >>> http://www.aaib.gov.uk/cms_resources.cfm?file=/1-2010%20G-YMMM.pdf

 >> You don't read my posts, remember?

 TM> Oh, sorry. I made a mistake. I'll try an not let it happen again. :-)

Damned straight you won't!

 >> Anyway, my source says he made a typo,
 >> 777 it was. But unlike what Ward said, it was an event, not a crash.

 TM> Well, since English is not my native language, may be I have
 TM> difficulties seeing the difference here?

No doubt, in my opinion.

 TM>  The report from The British Department of Transport, Air Accident
 TM> Investigation Branch, uses the term accident here.

Well, they do call it an 'accident investigation report' - due to the
lack of a better term, I suppose. I mean, that's what they do, although
the AAIB were back seat drivers as the USA's NTSB was more involved than
AAIB was.

 TM>  BH28 touched down 300m short of the runway, damaging the
 TM> undercarriage, injuring one passanger seriously. Crash, Accident ok,
 TM> but an EVENT?

"Boeing 777-236ER, G-YMMM, at London Heathrow Airport on 17 January 2008"

"This investigation was carried out in accordance with The Civil Aviation
(Investigation of Air Accidents and Incidents)"
                                    ^^^^^^^^^
Event-------------------------------|||||||||

I'll comprimise with ya and we'll call it an 'incident'...The airplane
certainly didn't crash, as the term is loosly stated in what you would
call it.

"Regulations 1996 The sole objective of the investigation of an accident
or incident under these Regulations shall be the prevention of accidents
and incidents. It shall not be the purpose of such an investigation to
apportion blame or liability"

"Crown Copyright 2010"

 TM> Explain to me when such an event becomes a crash then please.

that's easy, even for a non-native English speaker. When an aircraft and
all/or a portion of those aboard perish...

"Whilst on approach to London (Heathrow) from Beijing, China, at 720 feet
agl, the right engine of G-YMMM ceased responding to autothrottle commands
for increased power and instead the power reduced to 1.03 Engine Pressure
Ratio (EPR). Seven seconds later the left engine power reduced to 1.02
EPR. This reduction led to a loss of airspeed and the aircraft touching
down"

Note: "touching down" is not the same as crashed down. You know, she did
have her flaps and landing gear down, throttles back and looking to, errr,
touch down.

"some 330 m short of the paved surface of Runway 27L at London Heathrow.
The investigation identified that the reduction in thrust was due to
restricted fuel flow to both engines. It was determined that this
restriction occurred on the right engine at its Fuel Oil Heat
Exchanger (FOHE). For the left engine, the investigation concluded that
the restriction most likely occurred at its FOHE. However, due to
limitations in available recorded data, it was not possible totally to
eliminate the possibility of a restriction elsewhere in the fuel system,
although the testing and data mining activity carried out for this
investigation suggested that this was very unlikely. Further, the
likelihood of a separate restriction mechanism occurring within seven
seconds of that for the right engine was determined to be very low."

Furthermore, just to cover some previously visited information that also
pertains to the latest 777 'incident' :

`a i r s p e e d  l o w' and stall warning On the Boeing 777 the minimum
manoeuvre margin for the aircraft is displayed as an amber band on the
Primary Flight Display (PFD) airspeed tape. This indicates a speed margin
above the stick shaker speed and below the minimum manoeuvre speed. When
the aircraft's airspeed reduces below the minimum manoeuvre speed, and by
an additional 30% of this margin, an amber caution message, `a i r s p e
e d l o w', is displayed on EICAS. In addition the master caution lights
illuminate and an aural warning sounds. The stall warning system on the
Boeing 777 operates when the aircraft's computed angle of attack (AoA)
is too high and warns the flight crew that the aircraft is about to enter
or has entered a stall. The AoA at which the warning occurs is calculated
within the Warning Electronic Unit (WEU), which uses inputs from various
aircraft systems, including the Air Data Inertial Reference Unit (ADIRU).
When the aircraft's actual AoA equals or exceeds the calculated stall
warning AoA, the stick shakers attached to the control columns operate.'

Want more?

There's also a report on how the 'autothrottle' operates, which SFB and I
argued about, he being the loser in that arguement if I release the info
on that.



         R\%/itt


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