Trident II

Reductions to MK-6 Guidance System Inventory Objectives May Be Possible Gao ID: NSIAD-94-192 July 6, 1994

The Navy plans to have 10 Trident II missile submarines by the end of fiscal year 1997. Each Trident II carries 14 D-5 missiles, and each missile is equipped with the MK-6 guidance system, which is comprised of an inertial measurement unit and an electronics assembly. The Navy maintains spare MK-6 guidance systems on board each submarine and in its logistics pipeline for test and maintenance purposes. The Navy carries six spare MK-6s on board each patrolling submarine. These inventory objectives are based on maintaining the same high levels of readiness and reliability that were originally established between 1986 and 1987 during the Cold War era. GAO found that reducing the number of on board spares to three would decrease the guidance system's operational readiness by only 3 percent, and reducing the number of spares to four would result in only a 0.66 percent decrease. GAO recommends the Secretary of Defense consider reducing the number of additional MK-6 guidance systems scheduled to be procured in coming years in light of the decreased threat following the break up of the Soviet Union and the end of the Cold War.

GAO found that: (1) the Navy based its inventory objective on maintaining the D-5 missile at a high level of readiness throughout the program's life; (2) the Navy calculated its program needs using methods that provided it with the highest number of MK-6 spares that might be needed at any time; (3) the Navy believes it does not have the experience to accurately predict its spare parts needs for a missile program whose expected life exceeds 20 years; (4) reducing the number of MK-6 spares on board each patrolling submarine from six to three would reduce operational readiness by only 3 percent; (5) reducing the number of MK-6 spares on board each patrolling submarine to four would reduce readiness by only .66 percent; (6) no Trident patrol has ever had more guidance system failures than it had spares; (7) operational readiness reductions would have a minimal effect on the D-5 missile's reliability; and (8) the spare parts reductions savings could range from $106 million to $159 million and current readiness and reliability levels would be reduced for only a few years.

Recommendations

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