PLT OF A PIPER PA28-140 FLEW ACFT TO HOME BASE AFTER DIVERTING TO ANOTHER ARPT IN AN EMER DUE TO A STUCK ENG THROTTLE CTL WITHOUT A MECH'S RELEASE FOR SVC; OR A FERRY PERMIT.

Narrative

A FRIEND AND I RENTED AN ACFT AND DECIDED TO FLY A XCOUNTRY FLT. PART 1 WOULD BE FLOWN BY ME TO MAUI (VFR). PART 2 WAS FLOWN BY MY FRIEND UNDER AN IFR FLT PLAN FROM MAUI TO HONOLULU. DURING PART 2 OF THE FLT (IFR); CTR TOLD US TO DSND FROM 6000 FT TO 4000 FT. WE TURNED ON CARB HEAT; REDUCED THROTTLE; AND BEGAN TO DSND. AFTER HITTING OUR ASSIGNED ALT; MY FRIEND (THE PIC) TRIED TO INCREASE PWR WITH THE THROTTLE; BUT THE THROTTLE WAS STUCK. NEITHER HE NOR I COULD MAKE THE THROTTLE MOVE. WITH THE REDUCED PWR APPLIED; WE WERE DSNDING AT 500 FPM WHETHER WE WANTED TO OR NOT. AFTER DECLARING AN EMER; WE BEGAN LOOKING FOR A PLACE TO LAND. AT THIS POINT WE ALSO AGREED TO TURN CARB HEAT OFF; THINKING THIS MAY BE CAUSING THE PROB. AT ABOUT 2000 FT; WE WERE ABLE TO MOVE THE THROTTLE AND MAKE A CTLED LNDG AT THE MOLOKAI ARPT. AFTER APPROX 2 1/2 HRS OF WAITING FOR A COMMERCIAL FLT OUT OF MOLOKAI TO HONOLULU; I BEGAN LOOKING IN MY 1999 FAR/AIM FOR ANY REG THAT SPECIFICALLY PROHIBITS FLT AFTER AN EMER SIT OR MECHANICAL PROB. AFTER SEARCHING THE FAR/AIM FOR ABOUT 20-30 MINS; I CONCLUDED THAT NOTHING SPECIFICALLY PROHIBITS FLT AFTER AN EMER OR MECHANICAL PROB (SO I THOUGHT). AFTER TALKING WITH MY FRIEND; WE BOTH CONCLUDED THAT WE WOULD VISUALLY INSPECT THE ENG AGAIN; RUN THE ACFT UP AND CONDUCT EXTENSIVE GND RUNUP CHKS WITH THE THROTTLE. AFTER EXTENSIVE GND RUNUP CHKS MOVING THE THROTTLE BACK AND FORTH; I CALLED THE OWNER OF THE ACFT AND TOLD HIM THAT MY FRIEND AND I FELT COMFORTABLE ENOUGH TO ONE-TIME-FLY THE ACFT BACK PROVIDED WE NEVER REDUCED THE THROTTLE BELOW 2300 RPM; AND NEVER USED CARB HEAT. HE AGREED. I AGAIN TALKED WITH MY FRIEND AND DECIDED I WOULD FLY THE ACFT BACK AS THE PIC. WE TOOK OFF OUT OF MOLOKAI ARPT; NEVER REDUCED THE THROTTLE BELOW 2300 RPM (UNTIL WE WERE ON SHORT FINAL INTO HONOLULU); NEVER USED CARB HEAT; AND RETURNED THE ACFT TO HONOLULU WITHOUT INCIDENT. A FEW DAYS AFTER THE FLT; I RECEIVED A CALL FROM THE FAA WHO INFORMED ME THE FLT WAS NOT AUTH. ALL OF MY FLT TIME; EXCEPT 50 HRS; IS WITH THE MIL; SO I WAS UNFAMILIAR WITH THE FAA'S POLICIES THAT MAKE AN ACFT 'NOT AIRWORTHY' ONCE A MECHANICAL PROB WAS IDENTED. I THOUGHT I WAS WITHIN MY AUTH TO DETERMINE WHETHER THE ACFT WAS AIRWORTHY FOR A ONE-TIME FLT BACK TO ITS HOME BASE. AFTER EXTENSIVE VISUAL CHKS AND GND RUNUP CHKS; AND WITH A PLAN OF ACTION THAT WOULD RETURN ME SAFELY HOME; I THOUGHT I WAS COMPLETELY WITHIN MY RIGHTS AS THE PIC TO DETERMINE WHETHER THAT ACFT WAS AIRWORTHY FOR THAT ONE-TIME FLT. I DID NOT KNOW THAT A 'FERRY AUTH' WAS REQUIRED NOR DOES THE FAR/AIM STATE CLRLY THAT REQUIREMENT. I ALSO KNOW THAT NO TIME WAS I INFORMED OF SUCH A REQUIREMENT. I THINK A MORE CLRLY WORDED FAR/AIM WOULD PREVENT A RECURRENCE.