What was found
INFLIGHT, WHEN APU WAS SHUTDOWN AT ABOUT 15,000 FT MSL, THE (MACH TRIM OFF) (AMB) AND (YD LOWER OFF) AMBER MSGS ILLUMINATED. CHECKLIST PROCEDURES WERE USED TO NO AVAIL. DURING DESCENT TO LAND, AT ABOUT 3000 FT MSL, THE (MACH TRIM OFF) MSG WENT AWAY. SHORTLY, THEREAFTER THE (YD LOWER OFF) MSG WENT AWAY. [SUP 4-19-07] SHORTLY, THEREAFTER THE "YD LOWER OFF" MSG WENT AWAY. FOUND DEBRIS IN LT AND RT PITOT TUBES. DISCONNECTED TUBES AND CLEANED. COMPLIED WITH "PITOT/STATIC SYSTEM LEAK CHECK IAW FAR 91.411, 4/09/07. WORK IAW CESSNA 750 M/M CHAP 34-11-01.