Date: 201312
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Night
Aircraft: Commercial Fixed Wing
Operating under: Part 121
Aircraft component: Engine Fuel Filter
Reporter organization: Air Carrier
Reporter function: Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Communication Breakdown; Confusion; Situational Awareness
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Other During Maintenance
Result: General Maintenance Action
Contributing factors: Human Factors; Incorrect / Not Installed / Unavailable Part; Procedure
Primary problem: Human Factors

Narrative: For the Job Card Maintenance Instructions Reference XX-0009 'LP Fuel Filter Element' sign-off; the Maintenance Reference XX-0009 states 'the following units only require Operational Check during Engine Test; if rejected; follow action noted below.' On Trent 800 Engines with Serial Numbers (S/N) XXXX-9 / XXXZ-Z; XXXX-1 /XXXY-Z; XXXX-3 / XXXZ-Z and XXXX-0 / XXXA-Z; I was assigned for these Test operations or Document Closing review. There were no faults during test or faults reported on the Repair Item pages. Engines successfully passed test.Hangar. Evening Shift.

Callback: Reporter stated that after an engine such as the Rolls Royce Trent 800 has gone through the Engine Build Line and been finalized; that engine is sent to the Test Cell for Operational Checks. One of the procedures for an engine run in the Test Cell is to remove the new oil Scavenge filter that had been installed during the Engine Build and temporarily install a much larger metal Special Test filter. That filter would later be cut in half to determine if any excessive metal deposits had been captured indicating a possible engine problem.Reporter stated that after Engine Run Operational Checks have been completed; the Test Cell mechanics have the responsibility to restore the engine to a Service condition. Part of that Post Run Check is to remove the Test Filter and install a new Scavenge filter on the engine. Recently; a Technician for an Operator of one of the Trent-800 engines noticed a filter had not been installed in the Engine Low Pressure (LP) Filter housing. That had never happened before and raised a lot of attention. Engineering and Quality Assurance (Q/A) got involved and ordered an Open-up Check of numerous filter housings to see if any other released Trent 800 engines were missing Low Pressure fuel filters. More Trent engines were found with missing LP filters. Reporter stated that miscommunication in the Engine Build Line group about the Test Cell procedures was later identified as a contributing factor. The Engine Build Line mechanics believed the Test Cell mechanics removed many of the new filters the Build Line had installed on Trent 800 engines and discarded them during the Test Cell preparations for an Engine run. Especially since the Build Line already knew the Test Cell had special Scavenge filters that would be used during the Engine Operational Checks. So; the thought was to save new filters and 'not' install other filters. Engine Build procedures have been revised and the problem corrected. All Test Cell mechanics have Airframe and Powerplant (A&P) licenses.



Synopsis: An Aircraft Maintenance Technician (AMT) reports how miscommunication between their Engine Build Line and Engine Test Cell mechanics contributed to Low Pressure Fuel filters not being installed on numerous Rolls Royce Trent-800 Engines.