A Lead Mechanic with an Inspection Authorization (I/A) rating reports that he failed to include another Mechanic's name in the logbook sign-off associated with a Cessna C-340 aircraft engine overhaul and installation. The aircraft was also found to have an exhaust gasket missing and the exhaust manifold misaligned; contributing to a potential inflight fire condition.

Narrative

I worked with another Airframe/Powerplant (A/P) and Inspection Authorized (I/A) Mechanic installing an overhauled engine. When the aircraft came in for an oil change seventy-five hours after the engine [was] installed; another Maintenance facility discovered the exhaust system was leaking. They stated a gasket was missing from the 'Y' pipe and the exhaust [manifold] was misaligned with the brackets which support it. During the investigation to how this occurred; it was discovered I failed to follow FAR 43.9(3) by [not] providing the name of the person I was working with.This failure of an incorrect installation was due to lack of experience of the installer and failure to follow the steps provided in a Service Bulletin on how to assemble the [exhaust] system. Though the service instructions were available and the parts were too; we as a team failed to go step-by-step on these instructions which resulted in the exhaust leak. Failure to identify this hazard could have resulted in an in-flight fire. I also believe this is a violation of FAR 43.13 Performance Rules; because we failed to use the methods prescribed in current manufacturer's Maintenance manuals.