Component Failure Analysis of J69-T-25A Engine

Component Failure Analysis of J69-T-25A Engine

Muhammad Asim Qazi (Center for Advanced Studies in Engineering, Pakistan), Irfan Manarvi (HITEC University Taxila, Pakistan) and Assad Iqbal (Bahria University Islamabad, Pakistan)
DOI: 10.4018/978-1-4666-3658-3.ch008
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Abstract

Reliability and serviceability of jet engines in the aviation industry is of paramount importance and is directly related to flight safety. Tight maintenance programs, including scheduled and preventive inspection are in place worldwide for jet engines to ensure air worthiness of aircraft. Old age provides maintenance maturity to the system, but on other hand, it requires focused efforts to ensure reliability due to aging factor. J69-T-25A falls in the same category, as it has been in service for the last six decades. Despite all maintenance efforts, a variety of defects are being faced on J69 engines. The major defects include RPM fluctuation, noise, oil gain, vibration, and smoke. The troubleshooting process identifies a number of components that cause these problems. this chapter is based on statistical analyses of component failure in terms of frequency and fault isolation. The top ten components were selected based upon failure rates and were compared against reported problems to establish a relationship between defects and failed components. Based upon the result, various remedial measures are suggested to reduce defects in the future and increase engine reliability.
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Methodology

The defects were collected from Log Books of engines for last two and half year (30 months). This data selection was done intentionally, with the aim to forecast and suggest remedial measures for remaining six months of Year 2011 through data analysis. Hours from last inspection and total operating life of top ten failed components was also collected from Log Books. The collected data was based upon following information:

  • 1.

    Date on which defect was reported.

  • 2.

    Defect category and nature.

  • 3.

    Root cause identifying defective component.

  • 4.

    Reason for component failure.

Total failures for each year were calculated. All scheduled and unscheduled engine removals were taken into consideration and in total 32 different components were identified. Top ten failed components were selected for analysis. The factors, affecting performance of components or contributing towards failure of component, like operating hours and operating conditions were used for failure analysis. During component failure analysis flight hours, schedule, and unscheduled removals cannot be over looked. Any failure during schedule inspection is expected that is the reason for schedule inspection after specified interval, whereas unscheduled removal is the major stakeholder for component failure analysis. The unscheduled removals help to decide component life, remedial measures, redefining inspection intervals, One Time Inspections (OTIs) and other steps to arrest the trend.

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Identification Of Defective Components

The Log Books of the engine were reviewed. The year wise data for scheduled removals and unscheduled removals was segregated. Figure 1 describes the year wise schedule and unscheduled removals, whereas Figure 2 describes the total flying for the year during which failures occur.

Figure 1.

Year wise unsch, sch, and total removals

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