THE FLC FERRIED DORNIER 328 WITH THE GEAR DOWN AT 25000 FT DUE TO HYD SYS PROB. THE LIMITATIONS WERE INTERPRETED BY A MANUFACTURER'S REPRESENTATIVE TO BE A MAX OF 18000 FT FOR GEAR EXTENDED OR GEAR OP.

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AN ERROR IN THE PROXI LOGIC SYS WAS GIVING ERRONEOUS INDICATIONS OF THE AUX HYD SYS AND LNDG GEAR POS. THIS DELAYED AND EVENTUALLY CANCELED OUR FLT. THE DECISION WAS MADE TO FERRY THE ACFT TO DFW WHERE THE SOFTWARE COULD BE REPLACED. MAINT APPROVED A FERRY FLT AT FL250 WITH THE ONLY RESTR PLACED ON THE SPECIAL FLT PERMIT THAT THE LNDG GEAR REMAIN DOWN AND LOCKED FOR THE ENTIRE FLT. THE ACFT FLT MANUAL (AFM) LISTS THE 'MAX ALT FOR LNDG GEAR OP' AS 18000 FT. SINCE THE GEAR WAS TO REMAIN DOWN AND LOCKED AND NOT OPERATED; NEITHER THE FLC OR MAINT CONSIDERED THIS LIMIT. AFTER TALKING TO THE MANUFACTURER SEVERAL DAYS LATER I FOUND OUT THE LIMIT IS ALSO MEANT TO INCLUDE OP WITH THE GEAR EXTENDED. THE AFM AND AOM SHOULD HAVE THE WORDING CHANGED TO MAKE THIS LIMIT CLR. IT WOULD ALSO BE CONSISTENT WITH OTHER LIMITS SUCH AS THE FLAP SYS. THE CHANGE WOULD ALSO MAKE THE WORDING CONSISTENT WITH FAR PART 1 DEFINITIONS. OTHER CONTRIBUTING FACTORS INCLUDE: THE CREW WAS TIRED AND HAD BEEN ON DUTY SINCE XX30. THE OUTSIDE AIR TEMP WAS VERY HOT MAKING THE COCKPIT EXTREMELY HOT DURING THE SEVERAL HR DELAY TRYING TO SOLVE THE PROXI PROB. THIS ALSO CONTRIBUTED TO FATIGUE. THE MECH ON DUTY AT THE OUTSTATION HAS NOT RECEIVED FORMAL TRAINING ON THIS TYPE OF ACFT YET.