4.2.8. Maintenance Issue

From Figure 8a, 'general' (substandard practices, insufficient maintenance, qualification, training, etc.) has the highest count, and the observed variation is statistically significant. Engine and part issues are as expected, while 'AD/SB' (failure to follow airworthiness directives or service bulletins) and 'PD' (repaired previous damage), have low counts. Figure 8b shows the distribution of system/componen<sup>t</sup> involved in accidents with maintenance contributions. The statistically significant result indicates that the landing gear is involved in 47% of accidents, with engine is in 26%. Given the unexpectedly high count for gear related issues, a further sub-code of gear issue was created for these 16 accidents (Figure 8c) where mechanical/structural/physical issues were identified as the most common.

**Figure 8.** Results for the maintenance and technical issues for accidents with maintenance contributions: (**a**) the broad maintenance issue; (**b**) the system or component involved in the maintenance issue; (**c**) the type of gear fault.
