Incident Overview
While in cruise flight at 12,000 feet mean sea level, the flight crew received a fire indication from the no. 2 engine. In response, they shut down the engine and subsequently landed the aircraft without further incident.
Investigation Findings
Post-landing examination revealed a cracked left fuel manifold segment in the no. 2 engine. Metallurgical analysis determined that the crack exhibited fatigue striations and was located at a position on the manifold where an abrupt change in material thickness occurred.
Previous Occurrences and Manufacturer Actions
The operator had reported two previous instances of cracked fuel manifolds, which were investigated by the National Transportation Safety Board. In response, the manufacturer had taken three actions prior to this incident: (1) introduced a redesign of manifold segments, (2) agreed to replace all operator manifold assemblies with the improved design, and (3) introduced an eddy-current inspection procedure for detecting manifold cracks.
Regulatory Actions
Following this incident, the Federal Aviation Administration mandated more frequent inspection intervals and the adoption of the new eddy-current inspection process for unimproved manifolds.