Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Net sale revenue	$ 113,573	$ 112,454
North America
Disaggregation of Revenue [Line Items]
Net sale revenue	98,144	95,667
Europe
Disaggregation of Revenue [Line Items]
Net sale revenue	15,429	16,787
Fixed wing aircraft
Disaggregation of Revenue [Line Items]
Net sale revenue	52,039	52,895
Rotorcraft
Disaggregation of Revenue [Line Items]
Net sale revenue	31,454	23,602
Energy components for power generation units
Disaggregation of Revenue [Line Items]
Net sale revenue	16,682	17,646
Commercial product and other revenue
Disaggregation of Revenue [Line Items]
Net sale revenue	13,398	18,311
Commercial revenue
Disaggregation of Revenue [Line Items]
Net sale revenue	48,335	54,999
Military revenue
Disaggregation of Revenue [Line Items]
Net sale revenue	$ 65,238	$ 57,455