NET PROPERTY

Property is stated at cost. Depreciation of property is based on estimated useful lives, generally using the straight-line method. Estimated useful lives for buildings and improvements range from 10 to 50 years and estimated useful lives for machinery and equipment range from 3 to 20 years. Significant improvements are capitalized, and disposed or replaced property is written off. Maintenance and repairs are charged to expense in the period they are incurred. Company-owned tooling is classified as property and depreciated over the shorter of its expected life or the life of the production contract, generally not to exceed three years.

In accordance with the FASB guidance on property, plant and equipment, the company reviews the carrying value of long-lived assets, excluding goodwill, to be held and used, for impairment whenever events or changes in circumstances indicate a possible impairment. An impairment loss is recognized when a long-lived asset’s carrying value is not recoverable and exceeds estimated fair value.

Net property is summarized as follows (in millions):



	September 30,
	2017			2016
Property at cost:
Land and land improvements	$	30		$	30
Buildings	240			231
Machinery and equipment	892			839
Company-owned tooling	126			113
Construction in progress	69			56
Total	1,357			1,269
Less: accumulated depreciation	(883		)	(830		)
Net property	$	474		$	439