Two Mechanics report a 7th stage intermediate pressure (IP) check valve had not been installed on a V2500 engine in the engine shop prior to installation on an MD-90 aircraft. The check valve was later installed at a downline station.
Synopsis
Two Mechanics report a 7th stage intermediate pressure (IP) check valve had not been installed on a V2500 engine in the engine shop prior to installation on an MD-90 aircraft. The check valve was later installed at a downline station.
Narrative
The quick engine change (QEC) fittings were being installed on an engine in the engine shop April 2010. The environmental control system (ECS) bleed air ducts were partially installed by Mechanic 'X' and the intermediate pressure stage (IP) 7th stage check valve was not installed in the duct prior to the duct being installed. The QEC was incomplete and it was decided that the remaining ducts would be robbed off the removed engine in ZZZ once the [replacement] engine arrived. The QEC installation paperwork was signed off as 'transferred to aircraft non-routine #XX'.I was assigned to go to ZZZ with Mechanic 'X' to finish the QEC installation. We completed the installation of the remaining ducts and I signed off the non-routine [write-up] as completed. The engine was installed on the aircraft and flew three days later. Upon return to work [at my base]; it was determined it was a possibility that the IP check valve may not have been installed. We contacted Maintenance Control and ZZZ was advised to check on the installation of the check valve; (the aircraft overnights in ZZZ). The check valve was not installed and ZZZ later installed the check valve without incident.
Second reporter narrative
While reviewing parts in the shop; it was discovered that the IP check value had not been installed. Maintenance Control informed me that the aircraft was in maintenance in ZZZ. Maintenance in ZZZ later confirmed missing valve.
NASA callback
Reporter stated his Air Carrier revised some of the maintenance paperwork for the quick engine change and improved on the reference pictures for 7th Stage Check Valve.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.