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Final Report for the HMMWV 
Engine Electrical Start System

Department of the ARMY – Electrical Start System

United States Army Tank-Automotive and Armaments Command

Warren, Michigan 48397-5000

Reply to the attention of:



SUBJECT: Final Report for the HMMWV Engine Electrical Start System

  1. The enclosed report on the HMMWV Engine Electrical Start System results from an independent assessment by Science Applications International Corporation of alternative approaches to solving HMMWV engine start system problems.
  2. Please review the report and provide me with written comments by 20 November. If you have any questions, contact me at 810-574–5338, fax 810-574-7835.

HMMWV engine control invention saved the US Government $197,723,520.

Final Report

Contract No. GS-35F-4461G, Order No. T0798BG0360

 The glow plugs can eventually reach a temperature at which they fail catastrophically. The “stacking” condition is the principal cause of premature glow plug failures, constituting a significant fraction of the total consumable costs to maintain the HMMWV. These failures in the primary engine starting system components can also precipitate secondary losses in other system elements. When a sufficient number of glow plugs have failed to prevent a cold engine start, the operator can bum out the starter motor with repeated unsuccessful attempts to start. 

Sources at TACOM IMMC have estimated that as much as 70% of all HMMWV starter motor replacements to these starting system problems. Although difficult to quantify reliably, additional manpower and material costs are reportedly incurred troubleshooting and replacing parts for incorrectly diagnosed issues caused by starting system failures. Consumable items that such unnecessary maintenance actions may impact include batteries and flywheels.

2.2.2 OSMIS Data Analysis

SAIC used the US Army Operating and Support Management Information System (OSMIS) database for FY90-96 and HMMWV Maintenance Allocation Chart (MAC) to determine the magnitude of costs associated with these engine starting system deficiencies. The HMMWV engine’s starting system components list in OS MIS among the “Top 200 Consumables” for the HMMWV, M1 097, and M997. Note that we have omitted the first year in the current OSMIS database (FY90) from our analysis. 

FY90 showed run unusually high demand for starter motors that we presume was due to unusual and non-repeating circumstances (possibly a design or manufacturing defect). The remainder of the OSMIS data showed fairly consistent demands over the FY91 to FY96 period. The new alternative system estimates realized savings that the cost data provides. (Addressed cost savings in section 4 of this report.)

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