ACFT EQUIP PROB. FAULTY FO ALTIMETER IN NORMAL STATIC SOURCE. AFTER LEVELOFF CAPT'S ALTIMETER WAS 2000 FT HIGHER THAN FO'S AND WHEN CHKING ALTERNATE STATIC SOURCES DETERMINED THE FO'S NORMAL STATIC SOURCE ERRONEOUS.

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DURING CLB TO ASSIGNED ALT OF FL350 WE NOTICED THAT CAPT'S ALTIMETER WAS READING APPROX 2000 FT HIGHER THAN BOTH THE FO'S AND STANDBY ALTIMETERS. WE TRIED TO DETERMINE WHICH ALTIMETERS WERE READING CORRECTLY. WE FOUND THERE WAS NO ABNORMAL PROC IN THE BOOK TO COVER THIS SIT. SINCE THE FO'S AND STANDBY ALTIMETERS WERE READING THE SAME AND WE WERE APCHING LEVELOFF ALT; WE LEVELED OFF USING THE FO'S ALTIMETER. WE ASSUMED THE CAPT'S ALTIMETER WAS READING HIGH SINCE THE FO'S AND STANDBY ALTIMETERS WERE READING THE SAME. AFTER LEVELOFF (USING THE FO'S ALTIMETER); THE CAPT SELECTED HIS ALTERNATE STATIC SOURCE AND HIS ALTIMETER READ THE SAME AS IT HAD READ IN NORMAL STATIC (FL370). WE THEN SELECTED THE FO'S STATIC SOURCE TO ALTERNATE AND BOTH THE FO'S AND STANDBY ALTIMETERS SPUN UP FROM FL350 TO FL370. WE IMMEDIATELY ADVISED ATC OF OUR INST PROBS AND REQUESTED AND WAS GIVEN A 2000 FT DSCNT BACK DOWN TO FL350. WE CONTINUED ON WITH FO'S STATIC SOURCE IN ALTERNATE POS. UPON LNDG IN SHV WE ADVISED MAINT AND GNDED THE ACFT.