Thanks, Jos, I share your frustration about not knowing the full
story (yet). Even when the immediate safety checks have been done it
will still be something of an act of faith that they will completely
preclude a repetition. I expect we'd all like to know very precisely
what happened before we could have full confidence that any
particular fix will prevent it from happening again. I also expect
that eventually we will reach that level of understanding and can go
back to trusting our beautiful little aeroplanes.
90kts was presumably the ground speed as taken from a radar trace.
Airspeed could easily have been +/- 30kts, maybe more, away from that
figure, given the effect of both wind and a possible steep dive.
Would a stab turn 90 degrees when its centre of pressure would be so
far aft of the torque tube? I would have expected it to continue to
point in roughly the right direction until and unless it came right off.
By the way, the Gasco seminar at Farnborough on 8 August is going to
include a tour of the investigation hangers where they do the
forensic analysis on recent wrecks. I believe that is where G-HOFC is
being examined.
Regards
Willie Harrison
On 23 Jun 2007, at 14:13, Jos Okhuijsen wrote:
>
> Hi William H.
>
>> We still can't avoid the question: why did this happen WHEN it
>> did? Mark makes a good point about slop, in any case, slop would
>> normally built up slowly. David's information about speed seems to
>> rule that out as a trigger event. Just a thought, but if one of
>> the stabs became disengaged, for any reason (sideways movement,
>> loss of TP14D pin - secured by a single small split pin) from the
>> TP12/13 drive flange, presumably the other stab would instantly be
>> countering all of the mass in the TP19 weights, thereby creating a
>> sudden and huge mass imbalance - enough to cause catastrophic
>> flutter?
>
> Somebody from the UK told me once: We are like mushrooms. We are
> kept in the dark, and once in a while we are allowed to see the
> light, and somebody throws shit at us. In this case i get the same
> feeling.
>
> Talking to Graham last night, we decided that at 90 knots there is
> very little chance of flutter. But the load on the tailplane is
> minimal at that speed. Now, if TP6 was loose, this was the time for
> the tail plane to move out wards, disengage from the TP 12 pins and
> turn square to the direction of flight, and so destroy itself,
> shake a wing loose and destroy the plane. Not necessarily in that
> order. But as said,we are kept in the dark and so on, so this is
> just another speculation.
>
> Regards,
>
> Jos Okhuijsen
>
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