Date: 201712
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Aircraft: B737-700
Flight phase: Parked
Aircraft component: Fan Blade
Component problem: Malfunctioning
Reporter function: Technician
Human factors: Troubleshooting; Training / Qualification
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Aircraft In Service At Gate
Result: General Maintenance Action
Contributing factors: Aircraft; Manuals; Procedure
Primary problem: Manuals

Narrative: My lead gave me a gate call with a report of a high engine vibration on Number 1 Engine on [the] aircraft. Once I was at the gate; my lead radioed me and asked me to do a data read and see what the Low Pressure Turbine (LPT) readings were for the last three flights. I found the last three flights to show vibrations of 3.27; 3.83; and 3.47. My lead explained that there is a Job Card that would allow us to document these figures and allow a Fan Trim Balance to be performed at the next Maintenance RON (Routine Overnight). I returned to the shop and showed these figures to my Lead. He said those numbers are below 4.0; which I agreed knowing that any vibration below 4.0 is considered in service per the AMM (Aircraft Maintenance Manual). While at the shop; I stopped to speak with my Supervisor and asked him if he would help me with the Serviceable Part Tag X Non routine card because I haven't had much experience with a Serviceable Part Tag X. He said he would and discussed how to sign off the logbook so that he log page and non-routine would be 'tied together'. I returned to the gate; signed off the log page; and returned to the shop to complete the Serviceable Part Tag X and call Maintenance Control.I sat down in the Supervisor's office and with my Supervisor; we proceeded to fill out Serviceable Part Tag X. A Serviceable Part Tag X was required by the Job Card statement of 'fill out a non-routine card to document the Fan Trim Balance to be performed at the 'next Maintenance RON.' Once we had the Serviceable Part Tag X filled out; the Supervisor and I were wondering if this would be a Maintenance note or what we should circle in the resolution type. I called Maintenance Control. I told the Maintenance Controller that the aircraft was a good aircraft and that we performed the data reading and completed the Job Card task card. He said he would return the aircraft to service. The Maintenance Controller asked me to 'scan all the paperwork and send it to him because the Aircraft is due to RON tonight and he would forward the paperwork to engineering to ensure it would be put on the RON paperwork for Maintenance that night.' I asked them about the Serviceable Part Tag X non-routine card and the resolution type. I asked them 'should this be a Maintenance Note because of the RON tonight?' He said no and I asked him; should it be a Left Turbine (LT) Limited Deferral? They said no and said to circle PL/Dent. I circled PL/Dent and scanned the paperwork to them; my supervisors and Records. The next day I asked what Maintenance found on the Fan Trim Balance? They said he didn't know but that the aircraft was not out of service. So; I didn't pay it any further attention until about mid shift today; when a Supervisor came to me and said that they were stopping [the] Aircraft because of the vibration and the overflying of the 'at next Maintenance RON' requirement was not completed by the overnight Maintenance. I asked the Supervisor how that happened and they explained to me that I didn't complete a Serviceable Part Tag Y for a LT Limited Deferral along with the Serviceable Part Tag X. After further discussion; it appears that I should have completed a Serviceable Part Tag Y for the LT Limited Deferral because a LT Limited Deferral cannot be documented on a Serviceable Part Tag X non-routine card.Per our Procedure Manual; the next maintenance visit should be 8 days. So; my question is; if I had completed the Serviceable Part Tag Y and deferred the Serviceable Part Tag X card like I should have; and deferred the Serviceable Part Tag X for up to 8 days; how did the Fan Trim Balance procedure really overfly? By the Job Card statement; it did because nothing was done by the overnight crew; but the Serviceable Part Tag Y would still have 5 days left. I feel the statement on the Job Card is misleading and confusing because it asks for a Serviceable Part Tag X non-routine card. Shouldn't the Job Card just ask for a Serviceable Part Tag Yknowing that the next maintenance visit is within 8 days? I also believe that the Job Card and the Procedure Manual really don't tie together on the time definition of 'next Maintenance RON' it could be anytime between 1 to 8 days and if it is less than 6 days then shouldn't it be documented on a Maintenance Note? I would [recommend] correcting the Job Card statement to say; document the performing of the Fan Trim Balance to be at the next Maintenance RON on a Serviceable Part Tag Y or document the performing of the Fan Trim Balance to be at the next Maintenance RON on a Maintenance Note which is 6 days or less. I also would ask for a quick reference guide or something similar for filling out the Serviceable Part Tag X and Serviceable Part Tag Y. Because on Line Service you rarely use the documents and having a quick reference to use would really help when you do need to fill a Serviceable Part Tag X or Serviceable Part Tag Y out.




Synopsis: A Maintenance Technician reported that a Fan Trim Balance on a Boeing 737 was not accomplished due to incorrect documentation.