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A B757-200 engine shop technician reports that while machining an engine part on a computer numerical controled machine it was discovered the reporter's internal micrometer was out of calibration.
| Attributes | |
| ACN | 715651 |
| Time | |
| Date | 200610 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : maintenance |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | maintenance : technician |
| ASRS Report | 715651 |
| Events | |
| Anomaly | aircraft equipment problem : critical maintenance problem : improper maintenance non adherence : published procedure non adherence : far |
| Independent Detector | other other : 2 |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other other |
| Factors | |
| Maintenance | contributing factor : engineering procedure contributing factor : work cards contributing factor : tooling performance deficiency : scheduled maintenance performance deficiency : non compliance with legal requirements |
| Supplementary | |
| Problem Areas | Maintenance Human Performance Aircraft |
| Primary Problem | Maintenance Human Performance |
Narrative:
Something during aug/xa/06; I became aware of the identification (inside dimension micrometer) microphone I was using were out of calibration. I was machining an engine part on a cnc (computer numerical control) machine; went to check the inside diameter. What the mikes read did not coincide with the machine's program; I got my lead technician involved; we checked the machine; made another pass on the part; cut nothing; then suggested I check my identification mikes. They were .025 or so out. I immediately took them to the tool room to be sent to calibration. These identification mikes are calibrated once every 12 months. We are told to check them with our od (outside diameter micrometer) mikes which have the calibration intervals 12 months and every mechanic in the building uses these od mikes that I am supposed to be using as a standard to check my identification mikes to. I am not present all the time these mikes are out on my work bench. All parts worked with the said mikes are being evaluated; and no part is flying at the moment.
Original NASA ASRS Text
Title: A B757-200 ENG SHOP TECHNICIAN RPTS THAT WHILE MACHINING AN ENG PART ON A COMPUTER NUMERICAL CTLED MACHINE IT WAS DISCOVERED THE RPTR'S INTERNAL MICROMETER WAS OUT OF CALIBRATION.
Narrative: SOMETHING DURING AUG/XA/06; I BECAME AWARE OF THE ID (INSIDE DIMENSION MICROMETER) MIKE I WAS USING WERE OUT OF CALIBRATION. I WAS MACHINING AN ENG PART ON A CNC (COMPUTER NUMERICAL CTL) MACHINE; WENT TO CHK THE INSIDE DIAMETER. WHAT THE MIKES READ DID NOT COINCIDE WITH THE MACHINE'S PROGRAM; I GOT MY LEAD TECHNICIAN INVOLVED; WE CHKED THE MACHINE; MADE ANOTHER PASS ON THE PART; CUT NOTHING; THEN SUGGESTED I CHK MY ID MIKES. THEY WERE .025 OR SO OUT. I IMMEDIATELY TOOK THEM TO THE TOOL ROOM TO BE SENT TO CALIBRATION. THESE ID MIKES ARE CALIBRATED ONCE EVERY 12 MONTHS. WE ARE TOLD TO CHK THEM WITH OUR OD (OUTSIDE DIAMETER MICROMETER) MIKES WHICH HAVE THE CALIBRATION INTERVALS 12 MONTHS AND EVERY MECH IN THE BUILDING USES THESE OD MIKES THAT I AM SUPPOSED TO BE USING AS A STANDARD TO CHK MY ID MIKES TO. I AM NOT PRESENT ALL THE TIME THESE MIKES ARE OUT ON MY WORK BENCH. ALL PARTS WORKED WITH THE SAID MIKES ARE BEING EVALUATED; AND NO PART IS FLYING AT THE MOMENT.
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.