Reviewing SR-111

These new insights (below at bottom by "beanspiller") say nothing much more than what we had either known, deduced or suspected. In particular:

A. Even though Boeing would have been pressing hard for the IFEN system to clearly be found wholly culpable, it does not matter where a fault is initiated because Kapton properties of wet and dry arc tracking are still what they are - it remains uniquely a most explosive wiring insulation. I would be rather surprised if the TSB came out with any statement of vindication for BMS-51 wiring insulation. And as far as I know, the Tefzel and Kapton were mixed in the same bundles, and that was most probably over the full length of the IFEN power-cable runs forward to the cockpit busses - including through that focally vulnerable point of the cockpit bulkhead.

B. "...instead of in conduit as required by law" - Just because the wiring was not in accordance with "best practice" doesn't mean that it catches fire. The actual point of ignition was most likely at a high chafe (and wiring flex) point - and it was later found that the front doors' ceiling-stowages provided those.

"It was very obvious that

> this piece of metal had been exposed to a very high heat to look like

> this. When I asked where it was from, I was told it was part of the

> door frame from the front passenger door behind the cockpit."

But there also remains the matter of the bus-tie sensing relays that had recently caused fires and failures (including on HB-IWF).

 

C. They would be hard-pressed denying that a fire starting anywhere might not have been propagated by the metallized mylar insulation - and that smouldering itself starting electrical arc-tracking fires in bundles anywhere, as wiring insulation became compromised by burning or charred by adjacent intense heat sources.

D. It is becoming fairly clear, if this gent (below) is correct and the TSB takes a primarily IFEN causation line, that STC'd add-ons must in future be approved in writing by the airplane manufacturer - both at the design and post implementation stage. It's just not sufficient for some FAA bean-counter many thousands of miles away to rubber-stamp "sign off" on it (or leave it to regulatory locals under parochial pressures (BASL)). The two main issues are design suitability and actual in-aircraft implementation (requiring an airframe by airframe inspection and sign-off).

E. That there was a fire of many thousands of degrees Celsius clearly indicates the involvement of the crew's high pressure oxygen system. For that to be involved (and have produced those fan-shaped patterns within the ceiling linings of the crown area), the stainless steel (or aluminum) oxy-piping to the RH jump-seat would have had to have been impinged upon by a Kapton arc. As soon as you have a resulting pinhole in that Stainless Steel tube, it ceases to melt due to the instantaneous highly localized cooling effect of the high-pressure oxygen escaping. And of course that blow-torch then creates the fan-shaped burn patterns - and would have been the sudden development that caused both pilots to simultaneously upgrade the emergency. Probably up to that point the situation might have been retrievable if they had gotten the power off the wire.

F. "Everyone from the cockpit, back to the middle of first class were unconscious upon impact." I am not sure that they could say this with any certainty - or why it would be so. Drop-down masks would have provided breathable oxygen and the g forces probably didn't get over about +3g (major discomfiture/inability to rise from seat [only]). I'd not heard, beyond my own speculation, that visible fire had affected the forward cabin to the extent it would have become uninhabitable.

G. The pilot's final loss of control was most probably a classic "loss of control in IMC (instrument meteorological conditions)" - except that in this case the obscuration would have been a mix of in-cockpit smoke haze and the external environment (night and cloud conditions, lack of "lights-on-the-ground" cues in the RH turn away from Halifax through West, North and East). It has already been acknowledged that the MD-11's standby artificial horizon needs re-wiring because of the lack of integrity of its own power source (emerg battery buss). So even though that AH was centrally located (i.e. offset from each pilot's own panel) and so would have been hard to "fly off", it is quite likely that it also ceased to function. The question of whether it froze, toppled (i.e. tumbled uselessly as gyros tend to do when they lose rigidity) or, worse still, froze without an OFF FLAG - is all a matter of conjecture. Whether deploying the ADG might have assisted is also doubtful (if the wiring was fire-affected). Whatever transpired to bring about that final loss of control, it is very likely that Cpt Zimmerman had first sprung from his seat to battle the very obvious and visually alarming outbreak of fire in the aft flight-deck ceiling. It's likely that he then quickly succumbed to the toxic fumes, either because of the rapid emptying of the crew oxygen (by the blowtorch) or because he had to go off oxygen to reach the seat of the visual fire. First Officer Loewe would have been so distracted by these events that I doubt that he would have actually "needed" the final straw of a STBY AH failure for him to lose control. Here I emphasize that there would have been reduced controllability anyway due to the LSAS flt control pitch stability system being disabled (and in addition the #2 engine had flamed out due to the electrics for its fuel pump being killed by either the fire or the checklist). Once a large fuel-laden jet's attitude gets dynamically past a certain angle of bank and pitch, the ability to recover (in the height available - or even at all) reduces - in part due to the much greater likelihood of sudden (or continuing) pilot disorientation. This is due to the increasing g forces and the vertigo-inducing effects of roll-rates in IMC flight [lack of any visual horizon or orienting features such as lights on the ground that are wholly distinguishable from stars in the night sky].

H. It's no doubt a case of SR-111 having been downed by:

1. Dubious wiring maint and insulation standards, marketing add-ons and initial design features (wire routing, buss connectivity, use of flammable thermal/acoustic mylar throughout the aircraft beneath the cabin lining, directly over wire bundles and in the presence of propagating airflows designed to dry out pools of aircon condensation)

2. The completely inappropriate checklist and training-inculcated "culture" of inflight trouble-shooting.

3. Unrealistic simulator scenarios that engendered false expectations of eventual checklist successes against fires of unknown origin.

4. Inadequate fire-detection and extinguishing provisions

5. The corporate belief (SR, Boeing, FAA, BASL) that ostensibly high standards (and "quality") can insulate against happenstance and error.

6. A continuing blinkered approach to the susceptibility (i.e. vulnerability coupled with a lack of redundancy) of aircraft wiring.

7. Reliance upon a computer-based interpretation, display (via synoptics screens ) and resolution of disassociated system failures (themselves all subject to failure). This has been likened to putting one's faith in a fire-engine that is itself on fire.

8. Failure to recognize the value of a Virgin Bus approach - to resolve the lack of redundancy through "escape-routing" a "fail-operational" survival course of action for incidents involving chaotically system-disabling (and auto-propagating) electrical fire.

In summary, this chap's insights into just what conclusions may be drawn (by the TSB) likely won't affect the known facts of the matter. Notwithstanding that the crew of SR-111 were eventually overwhelmed by cascading events, they clearly acted dutifully - and in accordance with their flawed training. The failure to filter out corrosive contaminants can eventually lead to a blockage failure in any system, particularly if fault-clearing procedures are unrealistic, open-ended - and basically optimistic. Getting bogged down in time-consuming procedural trouble-shooting is now generally accepted as "no way to combat a fire". However, short of the panacea solution of "Land ASAP", there has been no real addressing of the fire-in-the-air scenario since SR-111. If there had been a third flight-crew member actively involved in resolution of the situation, there may have been a different outcome. Fire in the air remains the greatest threat to an underway airliner. Steps need to be taken to provide crews with a reliable fall-back solution. It must already be apparent to authorities, aircrews and the traveling public that many happy outcomes of airborne electrical fire are attributable to nothing more than luck. Despite the patchwork quilt of band-aid electrical AD's since SR-111, the risk exposure remains virtually unchanged. If you explained that to passengers very literally and then polled them, I'm sure that they'd find that fact appalling. Fortunately, for the industry, passengers are disinclined to consider such stark facts, because they have always felt statistically secure.

JS

The intended Swissair MD-11 "FIX" (status now unknown)

and here    here    and    here


 

----- Original Message -----

From: "beanspiller_ca" <rburnell@accesswave.ca>

To: <sr111@yahoogroups.com>

Sent: Tuesday, August 13, 2002 9:21 PM

Subject: [SR111] RE Wiring

 

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> Ok here goes. The cause of the crash has been identified, but will not

> be released for some time. How do I know this..?? I have a friend who

> was involved in the aircraft reconstruction in Shearwater. He has

> informed me, that the cause was wiring, but it was not the Kapton

> wiring. It was the wiring for the inflight entertainment system. It

> seems that all the A/V equipment was stored in Galley 8 just ahead of

> the leading edge of the port wing. The wiring exited the cabin

> through the ceiling, and ran along the top of the cabin bulkhead, and

> down into the first class section and to the LCD screens in the back

> of the headrests in the first class section. The investigators

> discovered that all of this wiring was laid bare in the space above

> the cabin, instead of in conduit as required by law. This explains why

> the flight data and cockpit voice recorders stopped working 6 and a

> half minutes before impact. The aircraft hit the water inverted, and

> on an approximate angle of 79 degrees. The temperature in the cockpit

> was approximately 3000 degrees fahrenheit. It was so hot, that kevlar

> was burnt. Everyone from the cockpit, back to the middle of first

> class were unconscious upon impact. It is not known if or when this

> will be released. It still has to be accepted by the CTSB. I have also

> seen pictures of some of the debris. I was shown a pic of a piece of

> metal that was very blued and heat distorted. It was very obvious that

> this piece of metal had been exposed to a very high heat to look like

> this. When I asked where it was from, I was told it was part of the

> door frame from the front passenger door behind the cockpit. I hope

> this helps some people. I'm putting my neck on the line printing this,

> but you have a right to know.

>

> Beanspiller_ca

>

>

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