<< >> NASA ASRS Report 726639, February 2007

A B737-300 was dispatched with the #1 pitot and #1 auxiliary static probe heat inoperative. Maintenance controller deferred the #1 auxiliary pitot and static probe heat inoperative. Wrong probe was deferred.

Attributes
ACN	726639
Time
Date	200702
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Environment
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	ground : parked
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	oversight : coordinator
ASRS Report	726639
Person 2
Affiliation	other
Function	maintenance : technician
Events
Anomaly	aircraft equipment problem : critical maintenance problem : non compliance with mel non adherence : far non adherence : published procedure
Independent Detector	aircraft equipment other aircraft equipment : probe heat control & ind. panel other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	other other
Factors
Maintenance	contributing factor : schedule pressure performance deficiency : fault isolation performance deficiency : logbook entry performance deficiency : non compliance with legal requirements
Supplementary
Problem Areas	Aircraft Chart Or Publication Environmental Factor Maintenance Human Performance
Primary Problem	Maintenance Human Performance

Narrative:

The captain made the correct write-up for 'captain P/south; 1 auxiliary static light illuminated' as can be seen on log page. The mechanic who called me on this; reported the same write-up. The error comes from myself by applying the wrong proviso of MEL. I interpreted the write-up to go with the first proviso '#1 auxiliary pitot/static heater (right lower probe).' no day VMC restrs. The write-up is nearly identical here. The correct proviso in this case is proviso 3...'pitot/static heaters (upper probes)' as reported by the crew during preflight. Since the mechanic does not have an MEL book in his back pocket; he is relying on me for correct MEL application. There are 2 things that I can do to correct this error. First; I will have the mechanics verify for me; which light is illuminated in the cockpit. Second; I will have the same mechanic verify at the probes which heater is in fact inoperative. I have done this in the past however; I cannot explain why I did not think to do this here.

Related reports:

• 737 captain reported aircraft with an inoperative APU was di...

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Original NASA ASRS Text

Title: A B737-300 WAS DISPATCHED WITH THE #1 PITOT AND #1 AUX STATIC PROBE HEAT INOP. MAINT CTLR DEFERRED THE #1 AUX PITOT AND STATIC PROBE HEAT INOP. WRONG PROBE WAS DEFERRED.

Narrative: THE CAPT MADE THE CORRECT WRITE-UP FOR 'CAPT P/S; 1 AUX STATIC LIGHT ILLUMINATED' AS CAN BE SEEN ON LOG PAGE. THE MECH WHO CALLED ME ON THIS; RPTED THE SAME WRITE-UP. THE ERROR COMES FROM MYSELF BY APPLYING THE WRONG PROVISO OF MEL. I INTERPRETED THE WRITE-UP TO GO WITH THE FIRST PROVISO '#1 AUX PITOT/STATIC HEATER (R LOWER PROBE).' NO DAY VMC RESTRS. THE WRITE-UP IS NEARLY IDENTICAL HERE. THE CORRECT PROVISO IN THIS CASE IS PROVISO 3...'PITOT/STATIC HEATERS (UPPER PROBES)' AS RPTED BY THE CREW DURING PREFLT. SINCE THE MECH DOES NOT HAVE AN MEL BOOK IN HIS BACK POCKET; HE IS RELYING ON ME FOR CORRECT MEL APPLICATION. THERE ARE 2 THINGS THAT I CAN DO TO CORRECT THIS ERROR. FIRST; I WILL HAVE THE MECHS VERIFY FOR ME; WHICH LIGHT IS ILLUMINATED IN THE COCKPIT. SECOND; I WILL HAVE THE SAME MECH VERIFY AT THE PROBES WHICH HEATER IS IN FACT INOP. I HAVE DONE THIS IN THE PAST HOWEVER; I CANNOT EXPLAIN WHY I DID NOT THINK TO DO THIS HERE.

Data retrieved from NASA's ASRS site as of January 2009 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.