Heavy duty: overhaul under way for Abrams tank engine.

The Army is revamping its Abrams tank engines in an effort to curtail soaring operating costs. Under a program called total integrated engine revitalization, or TIGER, the goal is to double the meantime between depot repairs for the M1 Abrams tank power plant.

The Army Tank-automotive and Armaments Command estimates that the Honeywell AGT1500 gas turbine engine accounts for about 42 percent of overall M1 support costs. "It's the number one target for reducing the cost of operating the tank," says Abrams Product Manager Lt. Col. Michael Flanagan.

The Army now has more than 6,000 M1 Abrams tanks and bought the last of the approximately 12,000 new AGT1500 engines in 1994. With its high power density, the thirsty 1,500-horsepower turbine made the Abrams a success in fast-moving Operations Desert Storm and Iraqi Freedom. "The lethality of this tank is in the speed at which we can move around the battlefield," says Flanagan. "That's why we took a hit on fuel consumption when we selected this very good engine."

However, the time between AGT1500 depot-level overhauls has declined from 2,000 operating hours for a brand-new engine to 700 hours for one returned to stock from the depot. The Army nevertheless established a compelling business case for improving the AGT1500.

"The tank for all intents and purposes was built around this engine," says Flanagan. "You either improve what you have, or you buy a brand-new engine." The Army leadership concluded that "this is the most affordable and cost-effective approach to address the operating and support costs of our Abrams fleet."

Ultimate savings from the TIGER program are difficult to quantify, but the effort aims to cut depot visits in half. The intent is to extend time between depot repairs to at least 1,400 hours with improved durability, a standard engine configuration, efficient supply-chain management, fact-based maintenance and expanded field support.

Honeywell, TACOM, the Life Cycle Management Command and Anniston Army Depot integrate all the engineering and implementation steps necessary to cut engine support costs. According to Honeywell AGT1500 engineering manager, John Mason, "There's no single silver bullet out there."

By 2012, the Army plans to reduce its Abrams fleet to 2,500 tanks with 4,000 engines installed, in depot, or in war stocks. The TIGER program will renew approximately 1,000 engines a year for four years. In January, the Army awarded Honeywell a 12-month contract with three one-year options. "I've turned over to Honeywell control responsibility for all aspects of running this engine ... instead of us trying to dictate obsolete solutions," Flanagan explains.

The time between AGT1500 depot repairs varies with the engine configuration. Engines repaired under an earlier engine improvement program have about 200 of their 800 parts replaced and typically run 1,000 hours before their next depot cycle. Engines with more common return-to-stock repairs receive 25 parts and last just 700 hours.

TIGER engines will get 400 to 500 new parts and phase-in engineering improvements to stretch their depot intervals to at least 1,400 hours or a hoped-for 1,600 hours.

The first engines now in the TIGER program receive parts already in stock. "Right now, we're in the transition phase, explains Honeywell program manager Randy Williams. "We're burning down the government-furnished material."

Simultaneously, Honeywell engineers are developing component improvements to enhance durability in areas with known reliability problems. "We are in the process of designing and making those part improvements now," says Mason. The first improved parts will be introduced next year.

Honeywell is working with the Army to qualify an improved engine seal that promises to eliminate the smoke that often causes repaired engines to be rejected. "It's a very fine-tuning of a seal," says Mason. "It's not a major re-design, but it's going to eliminate smoke."

TIGER housing improvements are designed to shed or delay coking and improve mean time between depot returns. The redesigned housing has so far demonstrated a three-fold improvement in oil jet life and passed a 361-hour endurance test.

Advanced diffusion-cooling technology also promises to improve the durability of the engine scroll, liner, and other hot parts. However, Honeywell engineers have stayed away from exotic new materials that are subject to lengthy testing and uncertain supplies. "Even as we go forward, we're not going to save or make great gains by going to a high-tech material," says Mason. "We're just trying to bring to bear the most recent technology available and use the best processes for reviewing the parts."

The government has long ordered AGT1500 parts from hundreds of different vendors with uneven quality and delivery schedules. Engines repaired by Army divisions in the field with swapped parts have also been unpredictable.

Honeywell will acquire uniform components only from specially qualified vendors and will take responsibility for delivering the parts on schedule.

The contractor will also standardize the overhaul process performed at Anniston Depot, Ala., and at maintenance facilities overseas. Flanagan explains, "What Honeywell will bring into this is a commercial process to that overhaul with reduced variability, one-piece flow, all those things industry does out of necessity that the government hasn't had to do."

Industry-standard six-sigma quality disciplines that are based on collected data will be applied across the TIGER program to reduce the number of unnecessary part replacements. The same techniques will be used at Anniston Army Depot and TIGER repair sites.

Several sites are situated worldwide, including more than six in the United States. M1 engines are now repaired in Kuwait to avoid transportation delays that are associated with returning engines to Alabama. Repair sites are also operational in Korea and planned for Germany

Honeywell representatives at the sites have access to the latest technical documentation and perform only specified repairs. "We have a very structured, limited number of repairs," says Mason. "If the extent of the problem goes beyond that, the engine goes back to Anniston."

Parts are ordered and replaced based on actual fleet consumption. Fact-based engine maintenance nevertheless requires timely data. "In the 30 years we've had that engine in the fleet, we have very little data on how the engine performed other than when we replaced it," Flanagan says.

Honeywell representatives last year introduced a manual data collection scheme for the AGT1500 to record engine symptoms and identify key reliability drivers. Every engine failure is logged in a database, Mason says. "We are starting to get a pretty clear picture now as more data comes in from the field."

The TIGER program is also moving toward an on-board engine memory unit that will record fault modes with engine speeds and temperatures to define mission profiles. The engine manufacturer gained experience with similar systems on other military and commercial engine programs. The memory unit requirements are defined by Honeywell for devices purchased from an outside supplier. The data collector will enter the Army's overhaul system in April or May 2007 and feed computer models later compared to actual operating profiles.

Mason believes engine parts can be saved by better operating models and improved inspection techniques. "We will be able to reuse them and not throw away as many parts."

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