Narrative:

As I understand it; aircraft X experienced 2 crew reports of engine stalls on r-hand engine. These 2 occurrences happened about 2 weeks apart. After the second stall incident; the aircraft was flown on to ZZZ1 for inspection. I was assigned to do fault isolation manual 71-07-00 page 107 (visual check #4 -- stator vane unison ring/actuator linkage figure 104). To the best of my knowledge on feb/sun/05 I accomplished stator vane unison ring/actuator linkage -- visual check #4. Reference fault isolation manual 71-07-00 figure 104; line items 1 through 7. All items visual checked good. As I understand it; the aircraft was then ferried back to ZZZ2 where the engine was replaced. As I understand it; no stall occurred during this ferry flight. As I understand it; the engine shop found the variable stator vane out of rig by 1/8 inch. As I understand it; the procedure I used to accomplish fault isolation manual 71-07-00 figure 104; specifically line item 7; is in question. After review of fault isolation manual 71-07-00 figure 104; I stand by my original signoff as being accurate and correct. Signoff: 'accomplished stator vane unison ring/actuator linkage check #4 reference fault isolation manual 71-07-00 figure 104 items 1 through 7. All checked good.' enclosed is a detailed account of the events I was involved with on feb/sun/05. 1) on feb/sun/05 at XA30; I started my shift. 2) soon after; I contacted lead mechanic mr X for my job assignment. 3) lead mr X told me to go see mechanic mr Y for remaining work to be accomplished on right engine. 4) handed me fault isolation manual 71-07-00 page 107 (visual check #4 -- stator vane unison ring/actuator linkage figure 104). 5) mechanic mr Z was already present at r-hand engine when I arrived. Lead mechanic mr X was also present. 6) together; mechanic mr Z and I accomplished fault isolation manual 71-07-00 page 107 items 1 through 7. Lead mechanic mr X observed us accomplish this work. A detailed account of how I accomplished fault isolation manual 71-07-00 page 107 item line 7 (do a check of the rigging for the variable stator vane system). 1) as per item line 7A (manually extend the variable stator vane actuator as shown in step 5 above). Mechanic mr Z put a 1 1/4 inch open-end wrench on the flat of the bell crank (near center bearing) and manually extended the variable stator vane actuator to full extended position with handheld pressure. 2) as per item line 7B (install the check rig pins in the bell crank and synchronizing rings). I interpreted that the 'check rig pins' mentioned was 'a pin used to check the rig.' I selected a drill bit (I cannot recall drill bit size) to check rig. No reference was made on fault isolation manual 71-07-00 page 107 as to any specific pin to be used to check rig of variable stator vane and synchronizing rings. No reference was made on fault isolation manual as to any maintenance manual to use as reference for checking rig of variable stator vane and synchronizing rings. No one told me verbally or presented me with anything in writing to use any specific pin for the check rig pin. I asked lead mr X; 'where is the reference for the location of check rig pins; rig holes?' lead mr X then pulled out a page from his pocket which I recall was maintenance manual 75-31-01 page 502. It is an identical picture as the one shown on fault isolation manual 71-07-00 page 107; figure 104; but with the addition of location of 'rig holes' on bell crank. I now have been presented with 2 authority/authorized documents to use as reference to accomplish stated job. A) fault isolation manual 71-07-00 page 107 which I received from mechanic mr Y; B) maintenance manual 75-31-01 page 502 which I received from lead mechanic mr X. I now concluded I had sufficient information to accomplish fault isolation manual 71-07-00 page 107 steps 7A and 7B. As mechanic mr Z held bell crank in full extended position; I installed drill bit into rig holes of bell crank as per fault isolation manual 71-07-00 page 107; item line 7A and 7B. Drill bit installed into bell crank. I asked lead mechanic mr X to verify installation; and he did. Per fault isolation manual 71-07-00 page 107 item 7B: 'if you can install the check ring pins with no problems; the variable stator vane is rigged correctly.' since my only 2 authority/authorized reference documents (fault isolation manual 71-07-00 page 107 and maintenance manual 75-31-01 page 502) showed only the 'rig holes' in bell crank; I interpreted it to mean: use 1 check rig pin (drill but used) to check rig of variable stator vane and synchronizing rings. In other words; 1 pin checked variable stator vane and synchronizing rings simultaneously.

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Original NASA ASRS Text

Title: A B757-200 R-HAND ENG HAD A VISUAL CHK ON THE STATOR VANE ACTUATOR UNISON RING ACCOMPLISHED AND SIGNED OFF. REPEAT CHK BY ENG SHOP FOUND RING PT 125 INCHES OUT OF RIG.

Narrative: AS I UNDERSTAND IT; ACFT X EXPERIENCED 2 CREW RPTS OF ENG STALLS ON R-HAND ENG. THESE 2 OCCURRENCES HAPPENED ABOUT 2 WKS APART. AFTER THE SECOND STALL INCIDENT; THE ACFT WAS FLOWN ON TO ZZZ1 FOR INSPECTION. I WAS ASSIGNED TO DO FAULT ISOLATION MANUAL 71-07-00 PAGE 107 (VISUAL CHK #4 -- STATOR VANE UNISON RING/ACTUATOR LINKAGE FIGURE 104). TO THE BEST OF MY KNOWLEDGE ON FEB/SUN/05 I ACCOMPLISHED STATOR VANE UNISON RING/ACTUATOR LINKAGE -- VISUAL CHK #4. REF FAULT ISOLATION MANUAL 71-07-00 FIGURE 104; LINE ITEMS 1 THROUGH 7. ALL ITEMS VISUAL CHKED GOOD. AS I UNDERSTAND IT; THE ACFT WAS THEN FERRIED BACK TO ZZZ2 WHERE THE ENG WAS REPLACED. AS I UNDERSTAND IT; NO STALL OCCURRED DURING THIS FERRY FLT. AS I UNDERSTAND IT; THE ENG SHOP FOUND THE VARIABLE STATOR VANE OUT OF RIG BY 1/8 INCH. AS I UNDERSTAND IT; THE PROC I USED TO ACCOMPLISH FAULT ISOLATION MANUAL 71-07-00 FIGURE 104; SPECIFICALLY LINE ITEM 7; IS IN QUESTION. AFTER REVIEW OF FAULT ISOLATION MANUAL 71-07-00 FIGURE 104; I STAND BY MY ORIGINAL SIGNOFF AS BEING ACCURATE AND CORRECT. SIGNOFF: 'ACCOMPLISHED STATOR VANE UNISON RING/ACTUATOR LINKAGE CHK #4 REF FAULT ISOLATION MANUAL 71-07-00 FIGURE 104 ITEMS 1 THROUGH 7. ALL CHKED GOOD.' ENCLOSED IS A DETAILED ACCOUNT OF THE EVENTS I WAS INVOLVED WITH ON FEB/SUN/05. 1) ON FEB/SUN/05 AT XA30; I STARTED MY SHIFT. 2) SOON AFTER; I CONTACTED LEAD MECH MR X FOR MY JOB ASSIGNMENT. 3) LEAD MR X TOLD ME TO GO SEE MECH MR Y FOR REMAINING WORK TO BE ACCOMPLISHED ON R ENG. 4) HANDED ME FAULT ISOLATION MANUAL 71-07-00 PAGE 107 (VISUAL CHK #4 -- STATOR VANE UNISON RING/ACTUATOR LINKAGE FIGURE 104). 5) MECH MR Z WAS ALREADY PRESENT AT R-HAND ENG WHEN I ARRIVED. LEAD MECH MR X WAS ALSO PRESENT. 6) TOGETHER; MECH MR Z AND I ACCOMPLISHED FAULT ISOLATION MANUAL 71-07-00 PAGE 107 ITEMS 1 THROUGH 7. LEAD MECH MR X OBSERVED US ACCOMPLISH THIS WORK. A DETAILED ACCOUNT OF HOW I ACCOMPLISHED FAULT ISOLATION MANUAL 71-07-00 PAGE 107 ITEM LINE 7 (DO A CHK OF THE RIGGING FOR THE VARIABLE STATOR VANE SYS). 1) AS PER ITEM LINE 7A (MANUALLY EXTEND THE VARIABLE STATOR VANE ACTUATOR AS SHOWN IN STEP 5 ABOVE). MECH MR Z PUT A 1 1/4 INCH OPEN-END WRENCH ON THE FLAT OF THE BELL CRANK (NEAR CTR BEARING) AND MANUALLY EXTENDED THE VARIABLE STATOR VANE ACTUATOR TO FULL EXTENDED POS WITH HANDHELD PRESSURE. 2) AS PER ITEM LINE 7B (INSTALL THE CHK RIG PINS IN THE BELL CRANK AND SYNCHRONIZING RINGS). I INTERPED THAT THE 'CHK RIG PINS' MENTIONED WAS 'A PIN USED TO CHK THE RIG.' I SELECTED A DRILL BIT (I CANNOT RECALL DRILL BIT SIZE) TO CHK RIG. NO REF WAS MADE ON FAULT ISOLATION MANUAL 71-07-00 PAGE 107 AS TO ANY SPECIFIC PIN TO BE USED TO CHK RIG OF VARIABLE STATOR VANE AND SYNCHRONIZING RINGS. NO REF WAS MADE ON FAULT ISOLATION MANUAL AS TO ANY MAINT MANUAL TO USE AS REF FOR CHKING RIG OF VARIABLE STATOR VANE AND SYNCHRONIZING RINGS. NO ONE TOLD ME VERBALLY OR PRESENTED ME WITH ANYTHING IN WRITING TO USE ANY SPECIFIC PIN FOR THE CHK RIG PIN. I ASKED LEAD MR X; 'WHERE IS THE REF FOR THE LOCATION OF CHK RIG PINS; RIG HOLES?' LEAD MR X THEN PULLED OUT A PAGE FROM HIS POCKET WHICH I RECALL WAS MAINT MANUAL 75-31-01 PAGE 502. IT IS AN IDENTICAL PICTURE AS THE ONE SHOWN ON FAULT ISOLATION MANUAL 71-07-00 PAGE 107; FIGURE 104; BUT WITH THE ADDITION OF LOCATION OF 'RIG HOLES' ON BELL CRANK. I NOW HAVE BEEN PRESENTED WITH 2 AUTH DOCUMENTS TO USE AS REF TO ACCOMPLISH STATED JOB. A) FAULT ISOLATION MANUAL 71-07-00 PAGE 107 WHICH I RECEIVED FROM MECH MR Y; B) MAINT MANUAL 75-31-01 PAGE 502 WHICH I RECEIVED FROM LEAD MECH MR X. I NOW CONCLUDED I HAD SUFFICIENT INFO TO ACCOMPLISH FAULT ISOLATION MANUAL 71-07-00 PAGE 107 STEPS 7A AND 7B. AS MECH MR Z HELD BELL CRANK IN FULL EXTENDED POS; I INSTALLED DRILL BIT INTO RIG HOLES OF BELL CRANK AS PER FAULT ISOLATION MANUAL 71-07-00 PAGE 107; ITEM LINE 7A AND 7B. DRILL BIT INSTALLED INTO BELL CRANK. I ASKED LEAD MECH MR X TO VERIFY INSTALLATION; AND HE DID. PER FAULT ISOLATION MANUAL 71-07-00 PAGE 107 ITEM 7B: 'IF YOU CAN INSTALL THE CHK RING PINS WITH NO PROBS; THE VARIABLE STATOR VANE IS RIGGED CORRECTLY.' SINCE MY ONLY 2 AUTH REF DOCUMENTS (FAULT ISOLATION MANUAL 71-07-00 PAGE 107 AND MAINT MANUAL 75-31-01 PAGE 502) SHOWED ONLY THE 'RIG HOLES' IN BELL CRANK; I INTERPED IT TO MEAN: USE 1 CHK RIG PIN (DRILL BUT USED) TO CHK RIG OF VARIABLE STATOR VANE AND SYNCHRONIZING RINGS. IN OTHER WORDS; 1 PIN CHKED VARIABLE STATOR VANE AND SYNCHRONIZING RINGS SIMULTANEOUSLY.

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.