Maintenance technicians reported mandatory service bulletin was not completed on accessory gearbox of helicopter engine.
Synopsis
Maintenance technicians reported mandatory service bulletin was not completed on accessory gearbox of helicopter engine.
Narrative
The engine was installed on Aircraft X on Day 0. Prior to installation this engine went thru inspections and Maintenance at the engine shop. Seeing that the engine time was at 3597.22 hrs we (other base Mechanic) figured that the MO1 (Accessory Gearbox) had the updated front support (Support Assy") installed since any supports or MO1's over 2400 hrs were due replacement of the Support Assy. per Turbomeca Mandatory Service Bulletin; as noted in the engineering order. The inspection was not completed prior to being returned to the base for service. It was known that this Engineering Order (EO) requirement was listed on the maintenance due report under the "As Required" page but since we find other Inspections listed on the records that do not apply to the aircraft we figured it was there in error and we weren't concerned about it. During our airworthiness checks as one of our standard practice we would always look at the Support Assy pins but weren't documenting it in the aircraft log book or on the inspection form since we believed that this engine had the updated Support Assy installed. One day recently we had another Mechanic cover our base due to me being out on medical leave and the other Mechanic was out that day. The Temp Mechanic signed off the EO in the Aircraft Log Book. When I returned later from my medical leave I asked why was the EO signed off in the Log Book and figured that it was because it was on the records. At this time we decided to look further into the issue if the EO compliance was actually necessary. At this point the aircraft was already at the ZZZ Maintenance Facility out of service for numerous required AAIP Inspections. The other Mechanic and I went to the ZZZ facility and found that the Support Assy was the part number of a support that required the inspection and documentation of the EO and the inspection. As soon as we figured this out; we contacted our our lead AMT (Aircraft Maintenance Technician) and advised of the findings and error. Suggestions: A better review of records and log book entries after maintenance is performed away from home base."
Second reporter narrative
This engine was installed on Aircraft X on Day 0. Prior to installation this engine went thru inspections and Maintenance at the engine shop. Seeing that the engine time was at 3597.22 hrs we (other base Mechanic) figured that the MO1 (Accessory Gearbox) had the latest and greatest Support Assy" installed since any supports or MO1's over 2400 hrs were due replacement of the Support assy. per Turbomeca Mandatory Service Bulletin; as noted in the engineering order. Also not seeing a log book entry for the Engineering Order (EO) when the engine installation was completed was another factor to why we thought that the inspection was not required. It was known that this EO requirement was listed on the maintenance due report under the "As Required" page but since we find other Inspections listed on the record that do not apply to the aircraft we figured it was there in error and we weren't concerned about it. During our airworthiness checks as our standard practice we would always look at the Support Assy Pins but weren't documenting it in the aircraft log book or on the inspection form since we believed that this engine had the latest Support Assy installed. One day recently we had another Mechanic cover our base due to me being out that day and the other base Mechanic was still out on a medical leave. The Temp Mechanic signed off the EO in the aircraft log book. I didn't think much about this. When my other base Mechanic returned a bit later from their medical leave they asked why was the EO signed off in the log book and figured that it was because it was on the record. At this time we decided to look further into the issue if the EO compliance was actually necessary. At this point the aircraft was already at the ZZZ Maintenance Facility out of service for numerous required AAIP Inspections. Myself and the other base Mechanic went to the ZZZ facility and found that the Support Assy was the part number of a support that required the inspection and documentation of the EO and the inspection. As soon as we made this discovery we contacted our lead AMT (Aircraft Maintenance Technician) and told them of what we discovered. Suggestions: Better review of records and log book entries after Maintenance performed away from home base."
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.