Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 99,591	$ 113,573
Transferred over Time | Revenue from Contract with Customer Benchmark | Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Percentage of concentration risk	65.00%	59.00%
North America
Disaggregation of Revenue [Line Items]
Revenue	$ 81,719	$ 98,144
Europe
Disaggregation of Revenue [Line Items]
Revenue	17,872	15,429
Fixed wing aircraft
Disaggregation of Revenue [Line Items]
Revenue	38,474	52,039
Rotorcraft
Disaggregation of Revenue [Line Items]
Revenue	27,214	31,454
Energy components for power generation units
Disaggregation of Revenue [Line Items]
Revenue	20,390	16,682
Commercial product and other revenue
Disaggregation of Revenue [Line Items]
Revenue	13,513	13,398
Commercial revenue
Disaggregation of Revenue [Line Items]
Revenue	36,587	48,335
Military revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 63,004	$ 65,238