Narrative:

Prior to takeoff from stl on nov/xx/97, the pilot of flight was unable to achieve the elevator power-on light. Upon return to the gate and subsequent flight cancellation, an investigation was performed. The cause of the problem was the apparent backing off of the nut attaching the left elevator power boost cylinder to the left elevator. Normally this nut is torqued (via pli washer), safetied with a cotter pin and sealed with a 2-PART sealant. The aircraft operated for approximately 30 days since release from its maintenance base visit with this nut, apparently, loose. The company has completed its investigation which revealed more than 1 possible problem area with regard to maintenance practices. Scenario: both elevators were removed for maintenance. Both power boost cylinders were removed for excessive leakage. Event #1: the technician responsible for signing off the installation and safety of the new left cylinder on the company's universal 'maintenance sheet' did so after only attaching the cylinder to the stabilizer. At the time, the elevator was allegedly not installed. This 'installation and safety' sign-off was accompanied by the appropriate inspection sign-off. Reference the same 'maintenance sheet.' event #2: the elevators are installed several days after the power boost cylinders. This work is accomplished on company-generated 'routine' maintenance cards. No provision is made to verify safety of the cylinder attach nut on the work card. Event #3: the rig of the elevators is checked/verified and adjusted as necessary. I am the technician responsible for the sign-off of the rig on the left elevator. Referencing the 'maintenance sheet,' in order to proceed with the work, I had no reason to question the installation integrity of the left cylinder and nut because I noticed the sign-off lines on the 'maintenance sheet' directing the 'installation and safety' of the cylinder were completed and verified by an inspector. Although I made no adjustment to the rig of the left elevator because the travel and leakage tests revealed nothing out of limits, had adjustment been necessary, this is accomplished away from the cylinder on the opposite side of the elevator. (The summing link connecting the control tab to the cylinder control valve is inboard and above the location of the cylinder). Summary: the cylinder should probably not have been signed off as 'installed and safetied' by the technician in event #1. The nut attaching the cylinder to the elevator should have been torqued and secured (as per maintenance manual procedures) during the elevator installation in event #2. As the technician accomplishing the 'inspection/test' portion of the work in event #3, I should have verified for myself the integrity of the work done prior. (No mention is made in the appropriate maintenance manual section 'inspection/test' to perform any adjustments or verifications on the power boost cylinder.) callback conversation with reporter revealed the following information: the reporter said the 'maintenance sheet' or job card is misleading, step #4 has the boost cylinder installation which per the maintenance manual requires installing the pli washer, torque nut and then safety with a cotter pin, then inspection is made in step #5. The reporter said the elevator was not installed when the power boost cylinder was installed. The reporter states when the elevator was installed and rigged it would require adjusting the elevator with the attach nut previously torqued and safetied. The reporter said step #7 does not call out for reinspection of the attach nut if disturbed. The reporter said this unit slipped by and flew for 30 days until discovered. The reporter said the air carrier was reviewing the job card and may change the procedure.

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Original NASA ASRS Text

Title: A DC9-30 WAS DISPATCHED WITH THE L ELEVATOR PWR BOOST CYLINDER IMPROPERLY INSTALLED.

Narrative: PRIOR TO TKOF FROM STL ON NOV/XX/97, THE PLT OF FLT WAS UNABLE TO ACHIEVE THE ELEVATOR PWR-ON LIGHT. UPON RETURN TO THE GATE AND SUBSEQUENT FLT CANCELLATION, AN INVESTIGATION WAS PERFORMED. THE CAUSE OF THE PROB WAS THE APPARENT BACKING OFF OF THE NUT ATTACHING THE L ELEVATOR PWR BOOST CYLINDER TO THE L ELEVATOR. NORMALLY THIS NUT IS TORQUED (VIA PLI WASHER), SAFETIED WITH A COTTER PIN AND SEALED WITH A 2-PART SEALANT. THE ACFT OPERATED FOR APPROX 30 DAYS SINCE RELEASE FROM ITS MAINT BASE VISIT WITH THIS NUT, APPARENTLY, LOOSE. THE COMPANY HAS COMPLETED ITS INVESTIGATION WHICH REVEALED MORE THAN 1 POSSIBLE PROB AREA WITH REGARD TO MAINT PRACTICES. SCENARIO: BOTH ELEVATORS WERE REMOVED FOR MAINT. BOTH PWR BOOST CYLINDERS WERE REMOVED FOR EXCESSIVE LEAKAGE. EVENT #1: THE TECHNICIAN RESPONSIBLE FOR SIGNING OFF THE INSTALLATION AND SAFETY OF THE NEW L CYLINDER ON THE COMPANY'S UNIVERSAL 'MAINT SHEET' DID SO AFTER ONLY ATTACHING THE CYLINDER TO THE STABILIZER. AT THE TIME, THE ELEVATOR WAS ALLEGEDLY NOT INSTALLED. THIS 'INSTALLATION AND SAFETY' SIGN-OFF WAS ACCOMPANIED BY THE APPROPRIATE INSPECTION SIGN-OFF. REF THE SAME 'MAINT SHEET.' EVENT #2: THE ELEVATORS ARE INSTALLED SEVERAL DAYS AFTER THE PWR BOOST CYLINDERS. THIS WORK IS ACCOMPLISHED ON COMPANY-GENERATED 'ROUTINE' MAINT CARDS. NO PROVISION IS MADE TO VERIFY SAFETY OF THE CYLINDER ATTACH NUT ON THE WORK CARD. EVENT #3: THE RIG OF THE ELEVATORS IS CHKED/VERIFIED AND ADJUSTED AS NECESSARY. I AM THE TECHNICIAN RESPONSIBLE FOR THE SIGN-OFF OF THE RIG ON THE L ELEVATOR. REFING THE 'MAINT SHEET,' IN ORDER TO PROCEED WITH THE WORK, I HAD NO REASON TO QUESTION THE INSTALLATION INTEGRITY OF THE L CYLINDER AND NUT BECAUSE I NOTICED THE SIGN-OFF LINES ON THE 'MAINT SHEET' DIRECTING THE 'INSTALLATION AND SAFETY' OF THE CYLINDER WERE COMPLETED AND VERIFIED BY AN INSPECTOR. ALTHOUGH I MADE NO ADJUSTMENT TO THE RIG OF THE L ELEVATOR BECAUSE THE TRAVEL AND LEAKAGE TESTS REVEALED NOTHING OUT OF LIMITS, HAD ADJUSTMENT BEEN NECESSARY, THIS IS ACCOMPLISHED AWAY FROM THE CYLINDER ON THE OPPOSITE SIDE OF THE ELEVATOR. (THE SUMMING LINK CONNECTING THE CTL TAB TO THE CYLINDER CTL VALVE IS INBOARD AND ABOVE THE LOCATION OF THE CYLINDER). SUMMARY: THE CYLINDER SHOULD PROBABLY NOT HAVE BEEN SIGNED OFF AS 'INSTALLED AND SAFETIED' BY THE TECHNICIAN IN EVENT #1. THE NUT ATTACHING THE CYLINDER TO THE ELEVATOR SHOULD HAVE BEEN TORQUED AND SECURED (AS PER MAINT MANUAL PROCS) DURING THE ELEVATOR INSTALLATION IN EVENT #2. AS THE TECHNICIAN ACCOMPLISHING THE 'INSPECTION/TEST' PORTION OF THE WORK IN EVENT #3, I SHOULD HAVE VERIFIED FOR MYSELF THE INTEGRITY OF THE WORK DONE PRIOR. (NO MENTION IS MADE IN THE APPROPRIATE MAINT MANUAL SECTION 'INSPECTION/TEST' TO PERFORM ANY ADJUSTMENTS OR VERIFICATIONS ON THE PWR BOOST CYLINDER.) CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR SAID THE 'MAINT SHEET' OR JOB CARD IS MISLEADING, STEP #4 HAS THE BOOST CYLINDER INSTALLATION WHICH PER THE MAINT MANUAL REQUIRES INSTALLING THE PLI WASHER, TORQUE NUT AND THEN SAFETY WITH A COTTER PIN, THEN INSPECTION IS MADE IN STEP #5. THE RPTR SAID THE ELEVATOR WAS NOT INSTALLED WHEN THE PWR BOOST CYLINDER WAS INSTALLED. THE RPTR STATES WHEN THE ELEVATOR WAS INSTALLED AND RIGGED IT WOULD REQUIRE ADJUSTING THE ELEVATOR WITH THE ATTACH NUT PREVIOUSLY TORQUED AND SAFETIED. THE RPTR SAID STEP #7 DOES NOT CALL OUT FOR REINSPECTION OF THE ATTACH NUT IF DISTURBED. THE RPTR SAID THIS UNIT SLIPPED BY AND FLEW FOR 30 DAYS UNTIL DISCOVERED. THE RPTR SAID THE ACR WAS REVIEWING THE JOB CARD AND MAY CHANGE THE PROC.

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.