Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 21,454	$ 25,330	$ 65,269	$ 75,274
Revenue from Contract with Customer | Customer Concentration Risk | Transferred over Time
Disaggregation of Revenue [Line Items]
Concentration risk			58.00%	65.00%
North America
Disaggregation of Revenue [Line Items]
Revenue	17,051	22,794	$ 53,339	$ 62,578
Europe
Disaggregation of Revenue [Line Items]
Revenue	4,403	2,536	11,930	12,696
Fixed wing aircraft
Disaggregation of Revenue [Line Items]
Revenue	10,351	8,941	30,310	28,907
Rotorcraft
Disaggregation of Revenue [Line Items]
Revenue	4,067	6,065	11,982	21,668
Energy components for power generation units
Disaggregation of Revenue [Line Items]
Revenue	4,899	3,199	12,902	14,763
Commercial product and other revenue
Disaggregation of Revenue [Line Items]
Revenue	2,137	7,125	10,075	9,936
Commercial revenue
Disaggregation of Revenue [Line Items]
Revenue	11,863	6,453	29,729	26,453
Military revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 9,591	$ 18,877	$ 35,540	$ 48,821