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	Director, Operational Test & Evaluation
	FY98 Annual Report

SYSTEM DESCRIPTION & CONTRIBUTION TO JOINT VISION 2010

The Family of Medium Tactical Vehicles (FMTV) consists of fourteen variants of tactical wheeled vehicles based on a common truck cab, chassis, and internal components and two tactical trailers. The components are primarily non-developmental items integrated in rugged tactical configurations. The light-medium tactical vehicles (LMTV) are 2.5-ton payload capacity models consisting of cargo, airdrop cargo, and van variants. The medium tactical vehicles (MTV) are 5-ton payload capacity models consisting of cargo (with and without material handling crane), long wheel base cargo (with and without material handling crane), airdrop cargo, tractor, wrecker, dump, airdrop dump, fuel tanker, and expandable van variants.

FMTV supports Joint Vision objectives: focused logistics through the transport of troops, fuel and water distribution, ammunition distribution, and general cargo transport; and information superiority by providing mobility of shelters which contain the new generation of automated systems, sophisticated management information systems, and communications links. FMTV also supports precision engagement as the prime mover for towed artillery and as the chassis for the High Mobility Artillery Rocket System (HIMARS) (an MLRS derivative on a wheeled chassis).

DOT&E approved the FMTV TEMP on August 17, 1991. The acquisition strategy includes the LRIP award in October 1991 for 10,843 vehicles. There was a deferred production and separate R&D effort for companion trailers (2.5- and 5-ton), a MTV tanker, and a MTV expandable van. The Army made the full-rate production decision in August 1995.

OT was conducted at Ft. Bragg, NC, in three phases: Phase I, September to December 1993, was terminated for poor demonstrated reliability. Phase II, conducted June to November 1994, was interrupted and canceled when the soldiers of the test unit deployed to Haiti. Phase III, conducted April to July 1995, was the basis of the DOT&E B-LRIP report.

While the system proved effective and suitable, there were certain safety deficiencies, detailed in the report to Congress, that needed to be corrected before fielding. The Army made the corrections and confirmed the fixes in an abbreviated operational assessment performed in December 1995.

While the FMTV was found to be effective and suitable in operational testing in temperate zones, technical testing under Arctic conditions uncovered starting and braking problems and seal leaks. These problems have been fixed and their solutions will be confirmed with the testing of the A1 version under Arctic conditions in early 1999.

In early 1998, there were several incidents in which the front U-joint on the rear driveshaft disintegrated. This failure causes the driveshaft to whip around, sever the air-brake line, and causes (by design) the brakes to lock. Fortunately, no fatalities were attributable to this failure mode. Investigation by the Army uncovered a previously unknown driveline resonance that occurs at speeds in excess of 40 miles per hour. Consequently, a worldwide safety-of-use message was issued limiting the driving speed to 30 miles per hour. The Army determined that the driveline resonance causes the flywheel-housing to crack as well as the driveshaft to fail. All of approximately 7,000 FMTVs that had been fielded were inspected for these failures, and about 180 vehicles with cracks in their flywheel-housing were found. A number of alternative design changes to the flywheel-housing and driveshaft were investigated and formally tested. The final solution was a more robust flywheel-housing design cast out of nodular iron, and a less flexible driveshaft with a more sturdy U-joint design.

OT&E activity in FY97 consisted of planning activities in support of a User Evaluation in FY99 and an IOT&E of the remaining variants in late FY00.

There was extensive technical testing of the proposed fixes for the flywheel-housing and driveshaft failures. Six trucks with the new flywheel-housing and driveshaft designs were tested this past summer for 12,000 miles each.

The operational test of the FMTV was adequate to provide the information necessary to determine its operational effectiveness and suitability. The operational testing was carried out in as realistic an operational environment as could be achieved within the constraints of available test ranges, resources, and safety. The test fleet drove more than 200,000 miles. The FMTV is operationally effective, based upon the demonstrated fleet-wide probability of mission success of 0.96.

Overall the FMTV is operationally suitable. The tested FMTV fleet demonstrated better than the required reliability and operational availability. Based on test results, the trucks required less maintenance than allowed.

A TEMP with a current acquisition strategy, which addresses the variants not included in the IOT&E and a second source or subsequent contractor, is being finalized by the Army.

The failure modes of the flywheel-housing and driveshaft have not recurred.

The flywheel-housing and driveshaft design failures were not identified during the technical or operational test programs. This failure mode occurs as a result of fatigue when the truck has been subjected to speeds greater than 40 miles per hour for extended duration. The test philosophy was to test the trucks at what was thought to be a more taxing and stressful profile: 15 percent on cross-country, 15 percent trails, 50 percent secondary roads, and 20 primary roads. In retrospect however, it is clear that tactical vehicles do have a requirement for line haul missions where high speeds are sustained for long periods of time. Also, the mobility requirements for tactical vehicles generally include a requirement for higher clearances, and consequently, greater angles for the U-joints to accommodate. DOT&E has been involved closely with the technical tests conducted at Aberdeen to understand drive-shaft failures and has received contractor test results as well.

DOT&E requires access to all test reports in time to prepare its report to Congress. For example, the report of cold weather starting problems and leaks was briefed to the acquisition decision maker but the test report was not available until after the Milestone III decision.

The legitimate principles of acquisition streamlining must be carefully applied. There are two examples:

• Formal operational testing was started soon after the beginning of technical testing. The result was that significant production line quality control problems and some minor design problems were discovered in operational testing before they were found in technical testing. Subsequently, two further operational tests were required before the system demonstrated adequate operational suitability.



• A fairly standard and inexpensive vibrational mode analysis was not performed but would have been expected to lead to the discovery of the driveline resonance problems discovered this year.