B757 ACFT IN CLB AT 34000 FT EXPERIENCED SEVERE PITCH OSCILLATIONS RESULTING IN EXCESSIVE G LOADS AND INJURIES. RPTR CAPT ATTRIBUTES THE UPSET TO FAULTY ELEVATOR INPUTS; POSSIBLY THE PCU (PWR CTL UNIT). NO INDICATIONS ON THE EICAS (ENG INDICATION AND CREW ALERTING SYS).

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WHILE CLBING FROM FL310 TO FL350; WT OF ACFT APPROX 214000 LBS; ACFT STARTED TO DSND AT FL340. ACFT ON AUTOPLT AT TIME. RATE OF DSCNT INCREASED RAPIDLY. AUTOPLT TURNED OFF AND ACFT FLOWN MANUALLY. SPD OF ACFT AT THE TIME WAS MACH .790 PER ATC. SEVERE PITCH OSCILLATIONS SOON FOLLOWED IN DSCNT. ACFT AT TIMES UNCONTROLLABLE. SPD RANGED FROM 340 KTS TO 230 KTS. ACFT SHOOK VIOLENTLY WHILE PITCHING UP AND DOWN. AFTER BRIEFLY STABILIZING THE ACFT FOR A FEW MINS IN FL240 RANGE; OSCILLATIONS AND VIOLENT PITCHING UP AND DOWN RESUMED. ONLY PITCH AXIS WAS AFFECTED. ROLL AND LATERAL CTL NORMAL AT ALL TIMES THROUGHOUT FLT. DURING 20 MINS FROM ONSET TO TOUCHDOWN IN SRQ; AT LEAST 4 SETS OF SEVERE OSCILLATIONS AND TURB OCCURRED; EVEN AS LOW AS 11000 FT AND 270 KTS. SEVERE UP AND DOWN PITCHING LASTED SEVERAL MINS THROUGHOUT EACH EPISODE OF UNCONTROLLABLE FLT. FLT ATTENDANTS IN AFT GALLEY REMARKED THAT THE NOISE FROM ACFT SHAKING WAS DEAFENING. FOOD AND BEVERAGE CARTS SHOOK SO HARD THAT THEY CAME LOOSE FROM THEIR STATIONS. CHK AIRMAN DEADHEADING IN FIRST CLASS NOTED A SEVERE FLUTTER FELT THROUGHOUT DURATION. NO STALL WARNING; STICK SHAKER; OR OVERSPD ANNOUNCEMENTS OCCURRED. ENGS NORMAL IN ALL PWR RANGES. MAJORITY OF TIME FLT IN VMC CONDITIONS. ACFT SHOOK SO VIOLENTLY BOTH PLTS LOST HEADSETS AND CAPT'S SUNGLASSES CAME OFF. AT LOWER AIRSPD AND ON APCH ACFT FLEW NORMALLY. LNDG UNEVENTFUL. SUSPECT A POSSIBLE PROB WITH ACFT PITCH MODE FLT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR CAPT WAS VERY FRUSTRATED THAT NEITHER HIS COMPANY NOR BOEING ARE TAKING THE EVENT AS SERIOUSLY AS WARRANTED. THEY DO HAVE AN ONGOING INVESTIGATION AND BOEING IS SUPPOSED TO RELEASE THEIR CONCLUSIONS SHORTLY. INCLUDED IN BOEING'S INVESTIGATION IS A CLR AIR TURB/ACFT POS MODEL BECAUSE THEY BELIEVE THE UPSET WAS CAUSED BY TURB. THE CAPT; WHILE AGREEING THEY ENCOUNTERED SEVERE TURB; BELIEVES THE MAIN CAUSE WAS ELEVATOR MALFUNCTION. THE DFDR SHOWED A 5 UNIT SPLIT AT THE WORST OSCILLATION SHOWING THAT THE ELEVATORS WERE NOT IN SYNC. RPTR SUSPECTS THE ELEVATOR PCU (PWR CTL UNIT) WHICH; IF MALFUNCTIONING MAY BE DUE TO ONE OR MORE VALVES STUCK IN POS. A DEADHEADING CHK AIRMAN SAID THE ACFT WAS 'FLUTTERING' DURING THE UPSET. CAPT HAD CUTS ON HIS LEGS WHICH HE SUSPECTS WERE CAUSED BY TUCKING HIS LEGS BACK UNDER THE SEAT TRYING TO REMAIN IN HIS SEAT DURING THE OSCILLATIONS. AN EMER WAS DECLARED AND THE GND FIRE CREW MET THE AIRPLANE AFTER LNDG. 4 PAX WERE TAKEN TO THE HOSPITAL AND ALL THE FLT ATTENDANTS COMPLAINED OF INJURIES. AS FAR AS RPTR KNOWS NONE OF THE INJURIES WERE SERIOUS. 1 MALE PAX WAS SO TRAUMATIZED HE COULDN'T GET OUT OF HIS SEAT TO DEPLANE AT THE GATE. THE WX WAS VMC THROUGHOUT. WHEN THE FLC DSNDED TO A LOWER ALT AND SLOWED THE ACFT IT BECAME CONTROLLABLE AND OPERATED NORMALLY. RPTR SAYS THE SPD WAS A FACTOR WHICH; WITH UNCOMMANDED ELEVATOR MOVEMENT; WOULD MAKE SENSE -- THE FASTER THE SPD THE GREATER THE PITCH.