Support Aircraft:

Analysis of Air Force Decision To Replace CT-39 Aircraft

NSIAD-86-92BR: Published: Apr 1, 1986. Publicly Released: Apr 1, 1986.

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Pursuant to a congressional request, GAO reviewed the Air Force's decision to retire the CT-30 aircraft fleet and replace it with a mix of C-12F and C-21A leased aircraft.

GAO found that: (1) the Air Force used lease-versus-buy comparisons in its economic analysis of the options to replace the CT-39 aircraft and found that it was more economical to lease new aircraft than to continue operations of the existing CT-39 fleet or purchase replacement aircraft; (2) the Air Force's economic analysis was generally accurate, complete, and realistic; (3) although the full cost to extend the service life of the CT-39 fleet was not determined, the cost would have provided an additional economic justification for retirement of the CT-39; (4) although the Air Force's method of calculating leasing option costs reduced the estimated cost of leasing new aircraft over a 22-year period, the reduction did not affect the results which supported the decision to replace the CT-39; (5) there were significant differences in the operational capabilities of the CT-39 aircraft and the C-21F and C-21A aircraft; and (6) the Air Force would have to implement an extensive inspection and repair program and a series of safety and structural modifications to extend the service life of most of the CT-39 air fleet.

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