Narrative:

On 9/thur/89, I was involved in an engine change on aircraft XXXX, right hand side in san antonio, tx. I was senior mechanic over 4 trnees. During the power lever rigging check I found it necessary to re-index the power lever connection to the propeller pitch control. I did this by loosening the nut and bolt from the control arm. No safety wire was on the bolt prior to loosening. I made the necessary adjustments and tightened the nut and bolt, but failed to safety wire the bolt. The engine change was completed and I required inspection item inspected the engine installation, propeller installation and starter/generator installation, which were installed by the 4 trnees under my supervision. On 9/sun/89, at approximately XA00 near the airport in lubbock, tx, the propeller pitch control arm came loose and fell off at flight idle position during the approach on a training flight. The engine was not shut down and the plane landed safely. The mechanic based there for our company discovered the problem and reported it to the main office in san antonio. To prevent the arm from coming loose, the airframe maintenance manual calls out the use of .25' safety wire between the bolt head on the engine manufacturers propeller pitch control pointer arm and the airframe manufacturers power lever control arm bolt head. This problem should have been caught by an inspection of the engine control rigging by an rii inspector. However, since I made the adjustment and I was the inspector on the other installations, this inspection was overlooked. Also, the adjustment of this arm has long been considered as not needing rii inspection and was not caught by our maintenance control or quality assurance people until this incident, even though it is listed in our company maintenance manual as such. As soon as the incident was reported our dom sent alert bulletins to our outstations calling for immediate inspection of the propeller pitch control arm for proper safety. My company is now working with the local FAA to correct this problem. In the meantime, I have decided that prior to changing an engine, I will initiate a discrepancy report in the aircraft maintenance log for each adjustment that will and may be needed. For example: 1) 'adjust egt comp resistor,' 2) 'perform engine rigging check and make necessary adjustments per airframe manufacturers maintenance manual.' rii. This will not allow an aircraft to be released for flight before this required inspection has been done and signed off in the log.

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Original NASA ASRS Text

Title: MAINTENANCE REPAIR NOT PROPERLY COMPLETED AND CHECKED. COMPONENT FAILURE.

Narrative: ON 9/THUR/89, I WAS INVOLVED IN AN ENG CHANGE ON ACFT XXXX, RIGHT HAND SIDE IN SAN ANTONIO, TX. I WAS SENIOR MECH OVER 4 TRNEES. DURING THE PWR LEVER RIGGING CHK I FOUND IT NECESSARY TO RE-INDEX THE PWR LEVER CONNECTION TO THE PROP PITCH CONTROL. I DID THIS BY LOOSENING THE NUT AND BOLT FROM THE CONTROL ARM. NO SAFETY WIRE WAS ON THE BOLT PRIOR TO LOOSENING. I MADE THE NECESSARY ADJUSTMENTS AND TIGHTENED THE NUT AND BOLT, BUT FAILED TO SAFETY WIRE THE BOLT. THE ENG CHANGE WAS COMPLETED AND I REQUIRED INSPECTION ITEM INSPECTED THE ENG INSTALLATION, PROP INSTALLATION AND STARTER/GENERATOR INSTALLATION, WHICH WERE INSTALLED BY THE 4 TRNEES UNDER MY SUPERVISION. ON 9/SUN/89, AT APPROX XA00 NEAR THE ARPT IN LUBBOCK, TX, THE PROP PITCH CONTROL ARM CAME LOOSE AND FELL OFF AT FLT IDLE POS DURING THE APCH ON A TRNING FLT. THE ENG WAS NOT SHUT DOWN AND THE PLANE LANDED SAFELY. THE MECH BASED THERE FOR OUR COMPANY DISCOVERED THE PROB AND RPTED IT TO THE MAIN OFFICE IN SAN ANTONIO. TO PREVENT THE ARM FROM COMING LOOSE, THE AIRFRAME MAINT MANUAL CALLS OUT THE USE OF .25' SAFETY WIRE BTWN THE BOLT HEAD ON THE ENG MANUFACTURERS PROP PITCH CONTROL POINTER ARM AND THE AIRFRAME MANUFACTURERS PWR LEVER CONTROL ARM BOLT HEAD. THIS PROB SHOULD HAVE BEEN CAUGHT BY AN INSPECTION OF THE ENG CONTROL RIGGING BY AN RII INSPECTOR. HOWEVER, SINCE I MADE THE ADJUSTMENT AND I WAS THE INSPECTOR ON THE OTHER INSTALLATIONS, THIS INSPECTION WAS OVERLOOKED. ALSO, THE ADJUSTMENT OF THIS ARM HAS LONG BEEN CONSIDERED AS NOT NEEDING RII INSPECTION AND WAS NOT CAUGHT BY OUR MAINT CTL OR QUALITY ASSURANCE PEOPLE UNTIL THIS INCIDENT, EVEN THOUGH IT IS LISTED IN OUR COMPANY MAINT MANUAL AS SUCH. AS SOON AS THE INCIDENT WAS RPTED OUR DOM SENT ALERT BULLETINS TO OUR OUTSTATIONS CALLING FOR IMMEDIATE INSPECTION OF THE PROP PITCH CONTROL ARM FOR PROPER SAFETY. MY COMPANY IS NOW WORKING WITH THE LCL FAA TO CORRECT THIS PROB. IN THE MEANTIME, I HAVE DECIDED THAT PRIOR TO CHANGING AN ENG, I WILL INITIATE A DISCREPANCY RPT IN THE ACFT MAINT LOG FOR EACH ADJUSTMENT THAT WILL AND MAY BE NEEDED. FOR EXAMPLE: 1) 'ADJUST EGT COMP RESISTOR,' 2) 'PERFORM ENG RIGGING CHK AND MAKE NECESSARY ADJUSTMENTS PER AIRFRAME MANUFACTURERS MAINT MANUAL.' RII. THIS WILL NOT ALLOW AN ACFT TO BE RELEASED FOR FLT BEFORE THIS REQUIRED INSPECTION HAS BEEN DONE AND SIGNED OFF IN THE LOG.

Data retrieved from NASA's ASRS site as of August 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.