MD82 reported the standby altimeter out of flight manual limits 60 ft. Report cleared checks ok per ...

Attributes
ACN	359628
Time
Date	199701
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : rno
State Reference	NV
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	MD-82
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 250 flight time total : 16000 flight time type : 500
ASRS Report	359628
Person 2
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa other other : unspecified cockpit
Resolutory Action	none taken : detected after the fact other
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

On jan/xx/97, entry was made in aircraft maintenance log 'standby altimeter 90 ft above captain or first officer altimeter (60 ft limit aircraft operating manual 1).' it was signed off 'performed functional test of captain's/first officer's and standby altimeter per maintenance manual. No defects noted. Difference within maintenance manual limits.' on jan/yy/97 I was first officer on this aircraft and operated a flight from rno-lax-rno. On return to rno, maintenance and FAA met the aircraft. On inspection, the standby altimeter was removed and replaced. Following is signoff by maintenance 'found standby altimeter reading high on ground (4490 ft). Remove and replace standby altimeter as per maintenance manual. Operations and leak check good.' the altimeter (standby) was off by 90 ft in both cases. There appears to be confusion about what governs a satisfactory altimeter check. Aircraft operating manual states 60 ft tolerance. Maintenance manual claims 90 ft is within limits while another section of the maintenance manual requires removing and replacing followed by operations and leak check.

Original NASA ASRS Text

Title: MD82 RPTED THE STANDBY ALTIMETER OUT OF FLT MANUAL LIMITS 60 FT. RPT CLRED CHKS OK PER MAINT MANUAL LIMITS 90 FT. CONFLICT BTWN FLT MANUAL AND MAINT MANUAL LIMITS.

Narrative: ON JAN/XX/97, ENTRY WAS MADE IN ACFT MAINT LOG 'STANDBY ALTIMETER 90 FT ABOVE CAPT OR FO ALTIMETER (60 FT LIMIT ACFT OPERATING MANUAL 1).' IT WAS SIGNED OFF 'PERFORMED FUNCTIONAL TEST OF CAPT'S/FO'S AND STANDBY ALTIMETER PER MAINT MANUAL. NO DEFECTS NOTED. DIFFERENCE WITHIN MAINT MANUAL LIMITS.' ON JAN/YY/97 I WAS FO ON THIS ACFT AND OPERATED A FLT FROM RNO-LAX-RNO. ON RETURN TO RNO, MAINT AND FAA MET THE ACFT. ON INSPECTION, THE STANDBY ALTIMETER WAS REMOVED AND REPLACED. FOLLOWING IS SIGNOFF BY MAINT 'FOUND STANDBY ALTIMETER READING HIGH ON GND (4490 FT). REMOVE AND REPLACE STANDBY ALTIMETER AS PER MAINT MANUAL. OPS AND LEAK CHK GOOD.' THE ALTIMETER (STANDBY) WAS OFF BY 90 FT IN BOTH CASES. THERE APPEARS TO BE CONFUSION ABOUT WHAT GOVERNS A SATISFACTORY ALTIMETER CHK. ACFT OPERATING MANUAL STATES 60 FT TOLERANCE. MAINT MANUAL CLAIMS 90 FT IS WITHIN LIMITS WHILE ANOTHER SECTION OF THE MAINT MANUAL REQUIRES REMOVING AND REPLACING FOLLOWED BY OPS AND LEAK CHK.

Data retrieved from NASA's ASRS site as of July 2007 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.

MD82 reported the standby altimeter out of flight manual limits 60 ft. Report cleared checks ok per maintenance manual limits 90 ft. Conflict between flight manual and maintenance manual limits.