AN MD-11 CREW HAD PROBS WITH ITS SPD CTL AFTER TKOF.

Narrative

ON TKOF CLB OUT OF PDX; MD11 WAS FLOWN MANUALLY. BRIEFING TO PNF WAS TO CTL GLARESHIELD CTL PANEL AND FMS INPUTS. ACFT CLEAN SPD WAS 274 KTS. AT 1100 FT; I CALLED FOR PROOF; AND NOTICED THAT ACFT FELT MUSHY. AIRSPD HAD AN FMC COMPUTED 185 KTS ON THE INDICATOR AND RELIEF PLT ADVISED US THAT THROTTLES HAD COME BACK TOWARD IDLE. AT 1500 FT; I HEARD TKOF WARNING HORN INDICATING FURTHER THROTTLE REDUCTION. ALL ATTEMPTS TO REPROGRAM AIRSPD FAILED; INCLUDING CHANGING AUTOPLTS. ACFT MUSHED; DSNDED 200-300 FT AT 185 KTS. I DISCONNECTED THE AUTO THROTTLES; PUSHED THEM TO CLB PWR; CONTINUED A CLB PROFILE; RE- ENGAGED FMS SPD MANUALLY; RE-ENGAGED AUTOPLT AND CLB CONTINUED NORMALLY. AT THIS TIME; WE WERE ASKED BY DEP CTL IF WE WERE ABLE TO MAINTAIN A NORMAL CLB PROFILE. WE REPLIED 'AFFIRMATIVE' AND AT THIS TIME MANUAL CLB RESUMED. IN CLB PHASE; FMC 'COMPUTED' AIRSPD DID NOT GET ABOVE V2 PLUS 10. THIS MIGHT HAVE BEEN DUE TO THE FACT THAT I SELECTED PROF MODE IN ERROR; BUT ABOVE 1500 FT; I DID NOT SEE 'CLB LIMIT THRUST' ANNUNCIATED ON EAD. BOTH FO AND I TRIED RESETTING FMS SPD; TRIED TO ENGAGE FLT LEVEL CHANGE AND CHANGE AUTOPLTS TO NO AVAIL. THE COMPUTED AIRSPD DIDN'T MOVE FROM 185 KTS. DURING FLT AND APCH TO DEST; AUTO THROTTLES APPEARED SLUGGISH AND IN SOME CASES AIRSPD COMPUTATIONS WERE INCORRECT. I WROTE A SIMPLE NOTE IN LOGBOOK DESCRIBING THIS SIT; AND BRIEFED OUTGOING CREW. I FEEL THAT THE FMC'S ARE SENDING INCORRECT INFO TO THE AUTO THROTTLES; BUT MORE RESEARCH NEEDS TO BE DONE AND DOCUMENTED ON THIS ACFT.