Narrative:

After departure from ZZZ; passing through 8000 ft in the climb; the right engine of a BE60 twin engine aircraft had a sudden partial loss of manifold pressure. The engine continued to run; and all other indicators; including oil pressure; oil temperature; and egt/cht readings of all cylinders remained normal. However; manifold pressure could not be adjusted with the throttle. In fact; the aircraft was able to maintain a climb even with the reduced manifold pressure. A request was made with ATC to return to the origin airport to determine the extent of the problem; and an uneventful landing was made back at ZZZ. The aircraft was taxied to the FBO whereupon maintenance personnel determined that a screw had come out of the control linkage and subsequently replaced it. There were no further problems.

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Original NASA ASRS Text

Title: A BE60'S R ENG THROTTLE LINKAGE BECAME DISCONNECTED DURING CLB AFTER TKOF. THE ENG OPERATED AT REDUCED POWER DURING RETURN TO THE DEP ARPT.

Narrative: AFTER DEP FROM ZZZ; PASSING THROUGH 8000 FT IN THE CLB; THE R ENG OF A BE60 TWIN ENG ACFT HAD A SUDDEN PARTIAL LOSS OF MANIFOLD PRESSURE. THE ENG CONTINUED TO RUN; AND ALL OTHER INDICATORS; INCLUDING OIL PRESSURE; OIL TEMP; AND EGT/CHT READINGS OF ALL CYLINDERS REMAINED NORMAL. HOWEVER; MANIFOLD PRESSURE COULD NOT BE ADJUSTED WITH THE THROTTLE. IN FACT; THE ACFT WAS ABLE TO MAINTAIN A CLB EVEN WITH THE REDUCED MANIFOLD PRESSURE. A REQUEST WAS MADE WITH ATC TO RETURN TO THE ORIGIN ARPT TO DETERMINE THE EXTENT OF THE PROB; AND AN UNEVENTFUL LNDG WAS MADE BACK AT ZZZ. THE ACFT WAS TAXIED TO THE FBO WHEREUPON MAINT PERSONNEL DETERMINED THAT A SCREW HAD COME OUT OF THE CTL LINKAGE AND SUBSEQUENTLY REPLACED IT. THERE WERE NO FURTHER PROBS.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.