Metro Airlines, Inc., in a recent annual report to stockholders, included the following footnotes to its consolidated financial statements:

\section*{Property and equipment, depreciation, and amortization:}
Property and equipment are depreciated to residual values over their estimated service lives using the straight-line and declining-balance methods. Upon retirement or sale of property and equipment, the assets and reserve accounts are relieved of the cost and related accumulated depreciation, and the resulting gain or loss is recorded in income.
\section*{Maintenance:}
Metroflight charges maintenance expense, on the basis of hours flown, for the estimated costs of Convair aircraft block overhauls. The provision rate per hour is adjusted periodically to reflect actual experience in hours between the block overhauls and in the costs of overhauls. The costs of block overhauls are charged to the reserve for block overhauls when incurred.
Courtesy of Metro Airlines, Inc.
\section*{Required}
1. If Metro uses both straight-line and declining-balance methods to depreciate property and equipment, isn't the company in violation of the consistency principle? Explain.
2. Are the maintenance expenses discussed in the footnote best classified as ordinary repairs or extraordinary repairs?
3. Metro's method of accounting for maintenance expense is different than the normal procedure as described in this chapter. Describe the difference.
4. Why do you think Metro accounts for maintenance expense in the manner described instead of following the procedure described in this chapter?