in the RB211 product line due to lower Flight Equipment sales in the amount of $21.0 million, offset by higher CF6-80 leasing activity in the amount of $2.7 million.
Cost of sales in Asset Management Solutions decreased $20.2 million or 62.9%, to $11.9 million for the three months ended September 30, 2022, compared to the prior year period. The decrease in cost of sales was primarily driven by the sales decrease discussed above. Gross profit in the Asset Management Solutions segment decreased $8.1 million to $8.7 million, or 48.3%, for the three months ended September 30, 2022, compared to the three months ended September 30, 2021. The gross profit decrease is mainly attributable to lower revenues generated for the three months ended September 30, 2022, as noted above.
Aircraft gross profit margins decreased to 38.1% for the three months ended September 30, 2022, from 44.3% for the three months ended September 30, 2021 due to lower margin generated on USM sales. Engine gross profit margin was 44.1% for the three months ended September 30, 2022, an increase from 29.9% for the three months ended September 30, 2021, which was primarily the result of higher margin on Flight Equipment sales.
TechOps
Our revenue from TechOps increased by $6.0 million or 24.5%, to $30.4 million for the three months ended September 30, 2022, compared to the prior year period. The increase was largely driven by improved landing gear and component repair activities, along with increased demand for heavy MRO services in our Goodyear facility, partially offset by lower storage and related maintenance activities in our Roswell facility as operators continue to return aircraft into active status.
Cost of sales in TechOps increased $7.0 million or 42.2%, to $23.6 million for the three months ended September 30, 2022 compared to the prior year period, driven by higher cost of sales from landing gear and component repair activities due to additional volume. Gross profit in TechOps decreased $1.0 million, or 13.0% for the three months ended September 30, 2022 compared to the three months ended September 30, 2021, driven by lower gross profit of $1.0 million on MRO services. Gross profit margin decreased to 22.4% for the three months ended September 30, 2022 compared to 32.0% for the three months ended September 30, 2021, and was largely attributable to lower margin on MRO services of 20.7% for the three months ended September 30, 2022 compared to 29.5% during the three month ended September 30, 2021, driven by lower margin maintenance work at our Roswell facility.
Selling, General and Administrative Expenses
Selling, general and administrative expenses increased $1.2 million, or 5.2% to $24.0 million for the three months ended September 30, 2022, compared to the prior year period. The increase was mostly related to higher payroll expenses associated with market adjustments and additional headcount, as well as higher cost incurred on information technology and cybersecurity, and professional consulting fees.
Change in Fair Value of Warrant Liability
We account for our private warrants as a liability at their fair value, with changes in fair value recognized in our results from operations for the period. The fair value of our private warrants is determined using a Black Scholes option pricing model. For the three months ended September 30, 2022, we recorded a $2.0 million expense in fair value of warrant liability income, compared to a $2.1 million expense in the prior year period.
Interest Income (Expense)
Interest income was $0.4 million for the three months ended September 30, 2022, compared to $0.2 million expense for the three months ended September 30, 2021 and was primarily related to higher interest income, offset by unused balance fees on our amended and restated revolving credit agreement (the “Revolving Credit Agreement”).