Date: 201704
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Aircraft: A319
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Powerplant Mounting
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Inspector
Reporter qualification: Maintenance Powerplant; Maintenance Airframe; Maintenance Inspection Authority
Second reporter function: Technician
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
When detected: Routine Inspection
Result: General Maintenance Action
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

Narrative: Three lower engine mount pins found missing from sleeves on aft mount during heavy maintenance visit.During engine build up to bring engine up to QEC [Quick Engine Change] status prior to engine installation. The aft engine mount was installed on the engine. This entails putting the mount in place and inserting sleeves through the engine case and the bearings on the mount. Pins are then inserted in the sleeves and secured with metal straps on both sides of the pins. Bolts are then torqued to secure the straps in place.   The mount installation was done months ago. I cannot recall this specific occurrence with certainty since it's a fairly common procedure here.  These pins are fairly large. Even if the step of installing the pins was overlooked; the left over parts should have been obvious. Possible contributing factors: there were a lot of distractions in the hangar that month since it was new at the time with construction finishing touches going on; with a lot of activity moving in equipment and setting it up.Perhaps an added step to verify pins are installed at the end of mount installation would prevent a recurrence.


Second narrative: I was summoned to my supervisor's office and was briefed of the incident. The discussion was my involvement of the missing pin of the aft engine mount assembly. I viewed the enclosed pictures. The pictures had shown a view of the aft engine mount assy. The locking plate was installed through the sleeve with no pin. Just a darkened hole. That aft engine mount assy was installed and signed by me along with the inspectors stamp. It was at that moment when I had tried to recall the installation of that aft engine mount assy. Along with the implications of the missing pin. I had volunteered to work in the engine shop to assist in the engine buildup. [The aircraft] #2 engine was scheduled for replacement that evening. The atmosphere in the hangar and engine shop was a comfortable one. No stress nor concerns were felt that day. My first task was a visual one. What parts were needed; locate the parts and/or parts that are already installed whether safetying is required. I noted various fuel; oil & hydraulic drain lines that require installation. Once the drain lines were installed; I proceeded on to the next project. The fwd engine mount was then installed. An inspection representative was on hand to witness the torques and safetying measures of the fwd mount. The next component to be installed was the aft engine mount. This is where my mind tends to fail me. I do recall lowering the aft mount and aligning the attach points. I also recall the pins; sleeves and locking devices for that mount being present prior to installation. I recall sliding the locking devices through the slots of the sleeves and then rotating them to align up the holes of the flanges and then securing them in place. Whether the pins were installed at the time I just do not know. But the installation of the aft engine mount was signed off by me. So in that respect I am responsible.


Synopsis: Two air carrier Maintenance Technicians reported that during a heavy check on an Airbus 319 it was discovered that lower engine mount pins were missing.