Failure analysis of a brazed, stainless steel fuel injection line. (June 2018)

• Record Type: Journal Article
• Authors: Kral, Milo V.; Maher, Cynthia M.; McSwain, Richard H.
• Is Part Of: Engineering failure analysis. Volume 88(2018)
• Page Start: 54
• Page End: 62
• Publication Date: 2018-06
• Subjects: System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2018.02.014
• Languages: English
• ISSNs: 1350-6307

Abstract

Abstract: An aircraft fuel line was found to have fractured and caused an in-flight fire. A brief history of the general problem of cracking in brazed stainless steel fuel injection lines places this failure in context. The fracture mechanism was likely to be fatigue due to vibrations. Other factors contributed to the failure, such as an inappropriate braze repair and incorrect bend radius and location dimensions. The effectiveness of current airworthiness directives and manufacturer service bulletins are discussed. Alternative designs are suggested to prevent recurrence. Highlights: An aircraft fuel injection line fracture caused an in-flight fire. There have been many previously documented instances of fractured fuel lines. Scanning electron microscopy of the fracture surface revealed evidence that fatigue was most likely dominant failure mode. The fuel line had been improperly repaired using a copper‑phosphorus‑silver braze. This design is susceptible to failure and a change to an alternative design or material needs to be considered.