Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue	$ 21,853	$ 21,454	$ 62,394	$ 65,269
Revenue from Contract with Customer | Customer Concentration Risk | Transferred over Time
Disaggregation of Revenue [Line Items]
Concentration risk			47.00%	58.00%
North America
Disaggregation of Revenue [Line Items]
Revenue	15,391	17,051	$ 47,037	$ 53,339
Europe
Disaggregation of Revenue [Line Items]
Revenue	6,462	4,403	15,357	11,930
Fixed wing aircraft
Disaggregation of Revenue [Line Items]
Revenue	8,726	10,351	28,307	30,310
Rotorcraft
Disaggregation of Revenue [Line Items]
Revenue	4,067	4,067	11,960	11,982
Energy components for power generation units
Disaggregation of Revenue [Line Items]
Revenue	7,005	4,899	16,729	12,902
Commercial product and other revenue
Disaggregation of Revenue [Line Items]
Revenue	2,055	2,137	5,398	10,075
Commercial revenue
Disaggregation of Revenue [Line Items]
Revenue	13,086	11,863	34,629	29,729
Military revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 8,767	$ 9,591	$ 27,765	$ 35,540