AeroTech acquired an aerospace manufacturing facility on 1 January 20X2 for $4,000,000 with an estimated residual value of $400,000 and an estimated useful life of 20 years. The company uses the units-of-production depreciation method. Due to industry shifts, the company now forecasts the following net cash inflows: $600,000 on 31 December 20X4, $550,000 on 31 December 20X5, $500,000 on 31 December 20X6, and $450,000 on 31 December 20X7. Using a discount rate of 6%, the present values of $1 at the end of each year are: 0.94, 0.88, 0.82, and 0.77. Required: Perform an impairment test and update the depreciation schedule, providing detailed journal entries as of 31 December 20X4.