Department of the Army's Program To Modify 155-mm. M109 Self-Propelled Howitzers to an M109A5 Configuration

NSIAD-84-60: Published: Mar 26, 1984. Publicly Released: Mar 26, 1984.

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GAO reviewed the Army's program for modifying some of its self-propelled howitzers, a program estimated to cost $1.5 billion.

The Army has deferred approving the full-scale development of the improved howitzers because a cost and operational effectiveness analysis is still in progress, more definitive information on the number of howitzers that should be modified is needed, and the cost estimate needs to be updated. GAO believes that the Army exercised exemplary caution in withholding its approval considering the program uncertainties. The Army has consistently shown its concern about the program's affordability when it has rejected several costly alternative modification programs. GAO found that the Army has a program to procure new armored ammunition supply vehicles which would replenish the howitzer's supply of ammunition. The Army's current ammunition supply vehicle is unarmored and affords little protection to the crew or equipment. However, the Army plans to procure only enough armored ammunition supply vehicles to supply half of the howitzers which would be developed. The benefits resulting from improvements to the howitzers may be offset by the fact that the majority of the howitzers will continue to operate with an ammunition supply vehicle which lacks adequate protection. In addition, GAO believes that more information is needed on the operational availability during wartime of the cannon and the effect of the proposed added weight on the howitzer's mobility.

Recommendations for Executive Action

  1. Status: Closed - Implemented

    Comments: The Department of Defense (DOD) conducted such an analysis and concluded that those howitzers to be deployed in Europe will work with improved support vehicles, while the remaining howitzers will be deployed in the United States, and could continue to work with the M548 vehicle.

    Recommendation: The Secretary of Defense should direct the Secretary of the Army, during full-scale development, to perform an analysis that would determine whether it is cost-effective to modify the number of M109 howitzers that will continue to operate alongside the vulnerable M548 ammunition supply vehicles.

    Agency Affected: Department of Defense

  2. Status: Closed - Implemented

    Comments: According to DOD analyses, the lesser number of support vehicles will be sufficient to support the howitzers in Europe. The remaining howitzers can work with the M548, since they will operate in the United States.

    Recommendation: If it is not cost-effective to modify the number of howitzers that will continue to operate alongside the vulnerable ammunition supply vehicles, the Secretary of Defense should direct the Secretary of the Army, during full-scale development, to consider the option of modifying a lesser number of howitzers than the 1,500 now in the program, and apply the savings toward the procurement of additional, more survivable, M992 vehicles, if affordability considerations continue to limit the funds available for both programs.

    Agency Affected: Department of Defense

  3. Status: Closed - Implemented

    Comments: DOD decided to pursue in parallel a low-technology improvement program, and an advanced-technology program to reduce risk. DOD also decided to modify the howitzer suspension to accomodate a heavier vehicle without loss of mobility. The program schedule now calls for completion of test and evaluation before entering production.

    Recommendation: If the decision is to continue into full-scale development, before contracting for modification of a large number of howitzers, the Secretary of the Army should ensure that the tests in the next acquisition phase adequately demonstrate that the selected cannon replacement will achieve the Army's availability goal and the added weight resulting from the modifications will not materially degrade the howitzer's mobility.

    Agency Affected: Department of Defense: Department of the Army


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