For rate-making purposes, for air carriers receiving subsidy under section 406 of the Act, it is the policy of the Board that flight equipment depreciation will be based on the conventional straight-line method of accrual, employing the service lives and residual values set forth below:
[In percent]------------------------------------------------------------------------
Service
life in Residual value as
years percent of cost------------------------------------------------------------------------Turbofan equipment:
4-engine.................................. 14 2
3-engine.................................. 14 2
2-engine.................................. 14 2Turbojet equipment:
4-engine.................................. 10 5
2-engine.................................. 10 5Turboprop equipment:
4-engine.................................. 12 5
2-engine.................................. 10 15Wide-body equipment:
4-engine.................................. 16 10
3-engine.................................. 16 10------------------------------------------------------------------------ [PS-54, 38 FR 24643, Sept. 10, 1973, as amended by PS-99, 45 FR 82625, Dec. 16, 1980]