3. APU STARTER MOTOR RELIABILITY ANALYSIS P/N 2704506 – 4 AIRBUS A320S USING WEIBULL DISTRIBUTION AND FAILURE MODE AND EFFECT ANALYSIS AT PT INDONESIA AIRASIA

Abstrak

This study aims to determine the reliability value and failure characteristics of
the APU starter motor P/N 2704506-4, as well as to identify the failure mode qualitatively to
provide improvement recommendations for PT Indonesia AirAsia. The starter motor in the
auxiliary power unit (APU) is a vital component that functions to start the operating cycle.
The method used is a mixed method, with quantitative analysis through processing historical
time to failure data from 20 unscheduled removal cases using the Weibull distribution, and
qualitative analysis through failure mode and effect analysis. Data were obtained from the
Aircraft Maintenance Manual, Component Maintenance Manual, and semi-structured
interviews with engineers. The analysis results show a value of β = 2.029 (β>1) which
indicates a wear-out failure pattern. The scale parameter η recorded 3,095.71 flight hours
with a mean time to failure of 2,742.85 hours. Reliability projections show that at 2,800 hours,
reliability drops to 44.23% with a failure probability of 55.77%. The FMEA analysis identified
three failure modes: brush wear, terminal winding burn, and oil contamination. Of these,
brush wear was the dominant failure mode, with 12 cases and the highest RPN value (252).
The study concluded that starter motor failure is predictive and dominated by brush wear.
The primary recommendation is to transition to a preventive maintenance strategy through
visual inspection of brush wear indicators and scheduled replacement at 2,500–2,600 flight
hours to reduce unscheduled removals and increase aircraft availability.