usxguy wrote:Wondering if the 76 drivers can chime in here:
What are you guys doing at 7,000 feet and that far out? What systems are being used/initiated, etc... accidents are never just ONE item, they are always a series of events spurred by one. Just wondering if something could have triggered a mechanical disruption that took out the control systems (ie - hydraulic pump explode/fail/burst, etc - and wipe out other systems --- or a short in the circuit boxes that wiped out other systems).
My 0.02 worth of experience on the 767 (close to 5K hours on her)
Around 7000ft and with an MSL landing elevation (like KIAH), on a bumpy/wx busy arrival, we would be doing cruising along with AP/AT engaged, around 240kt and getting ready for the first speed reduction, in order to select Flaps 1. On traffic intensive areas, like the US, sometimes you can expect early reductions to 210kt, depending on the traffic ahead or the arrival flow. But nothing really out of the ordinary going on. The 767 is a highly automated aircraft in regards to systems operation, and besides selecting packs on or off (depending on the SOP) or turning the APU on, or activating the engine/wing anti-ice systems (when needed) the overhead panel is hardly used while airborne, under normal conditions.
Also, it was designed and built with ETOPS in mind, so the level of redundancies installed is very good. If you lose one (of the three) HYD SYS (hydraulic pumps don't explode, they might overheat and are turned off). If it is not the centre system, you can continue without much checklist work. The centre system powers the Flaps and Landing Gear, so losing it is a bit more complicated as you have to configure early using the alternate systems. But again, these scenarios are trained every year during recurrent training in the sim, so the crew should be proficient.