PPRuNe Forums - View Single Post - AAIB investigation to Hawker Hunter T7 G-BXFI 22 August 2015
Old 7th Mar 2017, 20:09
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Lemain
 
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Originally Posted by bvcu
Read that Lemain , quite scary as couldn't imagine signing that out as airworthy as it should have a duplicate inspection {independent} but that would cost two licenced engineers . So if done correctly shouldn't have been a serial number error . I'm guessing that a static leak at that altitude would have some effect but not as much as at altitude .
As the pilot had flown a few hundred miles shortly before probably fairly low level (VMC/VFR) on a fine day enjoying the flight, thinking of his display routine he might not have noticed any small deviations. I can think of 3 plausible scenarios:

1. Small leak in static line from the pitot-static tube(s) maybe in the wing section

2. Someone bashed the pitot-static head, while on the ground and didn't fess-up (Happened to me once and I nipped to ironmonger to buy Araldite Rapid so I could fly, I had a Special Cat CofA). It was a licensed engineer who bashed it for certain, and he'd buggered off for the weekend. It happens.

3. Something odd about that second servo-altimeter which must presumably share the same (one and only) static? Might there have been a connection problem between the two Alts?

Suppose there was a slow leak from the static in the port wing section. Might there be a venturi effect that decreased the static pressure line or, on the contrary, a positive pressure in the wing section that increased the static? If that was the case - and the Report states that the investigators could not determine that connection due to accident damage, then the venturi or increased pressure would, I imagine, be dependent on true airspeed and angle of attack of that wing section. It might result in some very odd indications on both of the altimeters and the ASIs. I realise there is the GoPro evidence but when I read that through for the third time it sounded a bit like water divining. Either you can read the instruments or you can't. They couldn't and they made assumptions.

The pilot was a senior captain with huge experience and respected by everyone in the industry. Obviously he can't remember - retrograde amnesia which I once had after a car crash. So I can relate to this pilot's situation. This pilot is not likely to have flown a display if he felt out of sorts. Yet they imply this highly respected pilot failed to enter his manoeuvre at the appropriate speed and altitude. Feels suspicious to me.
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