PPRuNe Forums - View Single Post - Barely controllable Tu-154 - another UA232
Old 5th May 2011, 13:14
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yaw_damper
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No control at all?

I was maintenance dipl. eng. in TU154 fleet. This aircraft has the following chain of controls:
From the Control Column mechanically to the upper left end of an ''H'' shaped mechanism witch is ground tied on structure with the lower left leg, the right lower leg is tied to structure through a hydro-electric device named RA-56 controlled by the RESPECTIVE MAIN CHANEL of the CENTRAL STABILIZATION computer (a block on lamps...) it is able to amend until to completely ignore the command from CC or Rudder pedals. From the upper right end of the ''H'' the movement goes to the control piston of the execution hydraulically powered device RP-56 (''R'' stands for rulevoy--->control, ''A'' stands for aftomaticeskyi--->automatic and ''P'' for privod--->device).

There are independently for each ONE OF THE THREE CHANNELS, three independent electro-hydro-mechanical chain of command as described above on each of the three independent hydro&electro systems.
I described the chain of controls, wanting to show that there is mandatory that ALL THIS NINE (3X3) CHANNELS ARE WORKING INTERDEPENDENTLY BUT IN CHAIN meaning that every pearl of the chain IS VITALLY IMPORTANT.

My personal opinion is that a CATASTROPHIC FAILURE in this chain of control has happened.

As Chief of the Technical Crew in OFFICIAL TECHNICAL FLIGHTS authorizing every TU154 in our fleet for normal flights each and every year, we were flying with all RA-56 OFF. At 6000ft with a rudder input, the pilot was able always in~150flts. to control the aircraft back to strait and level flight.
That is the reason why, my opinion, is that the failure was more complex, the A/C in the movie was obviously HARDLY, BALDLY OUT OF CONTROL!!!

Many, many regards to the crew. It is obvious they were pure heroes.
The shots of vodka were of course well greeted and swallowed.
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