Starglider
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What If G-YMMM Had Made It To The Runway?

Wed Jun 25, 2008 9:30 pm

Just a few hypothetical questions.
With the crash investigation now into its sixth month since G-YMMM / BA038 "touched down" on the grass approaching 27L at Heathrow on January 17 '08, i wonder, what if under the same circumstances, the T7 had made it to the runway intact?

With the yet to be determined cause(s) for the engines to roll back, would the aircraft have remained grounded to this day? Or, if after performing all conceivable fault isolation procedures had resulted in (as the investigation now officially stands) "could not duplicate fault", would the aircraft have returned to service?



Regards,
Starglider
 
tdscanuck
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RE: What If G-YMMM Had Made It To The Runway?

Wed Jun 25, 2008 10:09 pm



Quoting Starglider (Thread starter):
With the yet to be determined cause(s) for the engines to roll back, would the aircraft have remained grounded to this day? Or, if after performing all conceivable fault isolation procedures had resulted in (as the investigation now officially stands) "could not duplicate fault", would the aircraft have returned to service?

I think they'd swap engines and fuel pumps, do a detailed visual of the fuel system, and put it back in service. Hard to justify grounding an asset that expensive when you can't find anything wrong with it and you've replaced the components most likely responsible.

Tom.
 
GST
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RE: What If G-YMMM Had Made It To The Runway?

Wed Jun 25, 2008 10:13 pm

I'd expect they would have gone further and replaced all throttle controlling systems, but yeah, it would have returned to operations.
 
avioniker
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RE: What If G-YMMM Had Made It To The Runway?

Thu Jun 26, 2008 12:46 am

In an incident of this type (as opposed to the accident it was) it's normal for the manufacturer to take posession of the airframe until a resolution can be determined.
In other severe cases with other aircraft BAC has kept the plane for up to a year before returning it to the original owner and service.
The 747 pylon problems in 92 and 373EV in ANC comes to mind. Boeing kept the plane for a couple of months until they determined the ultimate cause (it wasn't the fuse pins) and a method to ensure it wouldn't happen again.
The regulations aren't specific but the consequences are. They're still settling the lawsuits over the 747 crashes after lost engines.
 Smile
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
GST
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RE: What If G-YMMM Had Made It To The Runway?

Thu Jun 26, 2008 9:15 am



Quoting Avioniker (Reply 3):
(it wasn't the fuse pins)

That had passed me by. What was it in the end?
 
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HAWK21M
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RE: What If G-YMMM Had Made It To The Runway?

Thu Jun 26, 2008 11:44 am

They'd probably replace both QECAs,check the fuel system,EECs & carry out a few Flight tests.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
avioniker
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RE: What If G-YMMM Had Made It To The Runway?

Thu Jun 26, 2008 5:38 pm

In the case of 473 it was some figure 8 drill holes in the center pylon hoop assy that led to cracking and failure in the area of the fuse pin bushings.
The #2 engine is canted in 2 degrees to take advantage of airflow at cruise speed but this also causes the engine inlet to oscillate in a figure 8 pattern which exascerbates any defect regardless of how minor.
When they did ultrasonic testing on the rest of the fleet they found the same thing on an awful lot of planes. The holes weren't obvious because of location and a number of them were in sandwich layers thus invisible. X rays didn't pick them up either.
The plane that led 473 out of ANC was found to have two of the fuse pins "crankshafted" because of the same problem that caused the pylon to flex much more than normal when it flew through the same windshear. It made it to JFK but no telling when the pins would have failed.
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One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
Starglider
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RE: What If G-YMMM Had Made It To The Runway?

Thu Jun 26, 2008 10:09 pm

Thanks for your replies. Perhaps the chances of finding the cause(s) for the mishap would have increased if the aircraft had been intact when compared to the actual damage inflicted.

Could the impact and subsequent damage to structure, components or wiring somehow have removed a failure mode, restoring an intermittent and possibly unrecorded fault of some kind back to a normal condition?


Starglider
 
GST
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RE: What If G-YMMM Had Made It To The Runway?

Thu Jun 26, 2008 10:31 pm



Quoting Starglider (Reply 7):

Could the impact and subsequent damage to structure, components or wiring somehow have removed a failure mode, restoring an intermittent and possibly unrecorded fault of some kind back to a normal condition?

I suppose its possible, but about as likely as an A380 being able to ride thermals and waves like an ASK-21.

The investigators are extremely good however, I'd put money on them finding the actual cause sooner or later, probably sooner.
 
Starglider
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RE: What If G-YMMM Had Made It To The Runway?

Sun Jun 29, 2008 10:02 am

To GST,

quote:
I suppose its possible, but about as likely as an A380 being able to ride thermals and waves like an ASK-21.
unquote

Or a B777 with 2 donks rolling back before you can count to 10 . . . . .

I agree, given time the investigators will present hard evidence to why this happened, 'most probable cause' just wouldn't be satisfactory to all parties involved.


Starglider

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