On Dec. 31, 2003, the entire 30-plus-seat turboprop industry's backlog totaled 49 units, or about 650 fewer than the number of regional jet orders in the pipeline. ATR, nursing a backlog of 15 aircraft, wrapped up an entire calendar year without adding a single net order. Oh, and paying for a gallon of U.S. Gulf Coast jet fuel with a dollar bill would get you at least a dime's worth of change.

What a difference a decade makes. As 2013 came to a close, the sub-100-seat regional jet backlog was still much larger than that of the large turboprops, but absent figures from upstarts Mitsubishi and Sukhoi, it shrank about 25% in a decade.

Turboprops, meanwhile, saw their backlog grow fivefold. Much of the reason for regional jet stagnation and turboprop resilience—a 250-aircraft backlog is hardly a boom—is in efficiency, and much of that comes down to fuel. This past December, paying $3 for a gallon of Gulf Coast would have netted the purchaser a dime back—on a good day. U.S. Energy Information Administration figures show spot prices at between $2.90 and $3 for most of the month, with a high of $3.03. Fuel's steady climb—it actually topped $1 per gallon for a few weeks in early 2003 before settling down again—started in early 2004. It topped $1 for good in May 2004, and last saw $2 in August 2010.

ATR, which based its entire company around large turboprops, arguably benefited most from the economic shift that helped make turboprops appealing and 50-seat regional jets uneconomical. The second-biggest benefactor may be Pratt & Whitney Canada (PWC) and its PW100 series engine.

Celebrating 30 years of in-service experience this year, the PW100 series has evolved into 31 models ranging in power from 1,800 shp to more than 5,000 shp. Counting all applications—besides moving passengers and packages, the PW100 series helps do everything from fight fires to patrol coastlines—PWC counts 365 operators in 124 countries as PW100/150 customers. More than 6,000 of the engines have entered service, and the latest versions regularly hit 10,000 hr. on-wing before removal is necessary, the manufacturer says. The company's PW100 series is entrenched as the regional turboprop market leader, earning high-profile spots on both active major large turboprop programs: the Bombardier Q400 line—for which the PW150 was purpose-built—and the ATR-42 and 72.

While these models make up the bulk of the installed base, they're hardly the entire in-service market. Of the 4,800 PW100-series engines the Aviation Week Intelligence Network's (AWIN) Fleets database shows in commercial service, about 265 operate Embraer EMB 120 Brasilias; another 212 power Fokker 50s. While these aircraft represent notable niches for the PW100, there's little doubt that the ATR/Bombardier combination dominates the scene. The ATR-42 entered revenue service in 1985 and has, with one notable dry spell, built steady momentum ever since. It averaged 100 deliveries every two to three years until a lean run in the early 2000s, during the 50-seat regional jet's heyday, saw the program go more than six years between deliveries 600 and 700. The pace picked back up, and the 1,000th ATR was handed over in 2012.

In 2013, the manufacturer set a single-year record with 74 deliveries, and this year's target is “at least” 80, says CEO Filippo Bagnato. ATR began the year with a backlog of 221 aircraft. AWIN Fleets lists 258 ATR-42 in service and 25 in storage, as well as 512 ATR-72s flying and another 14 in storage. Bombardier's Dash 8 family, including the Q400, boasts 487 in service and five in storage, including 376 Q400s. Both aircraft have shown their appeal as regional carrier workhorses in recent months; Hawaiian Airlines tapped the ATR to support its regional operation, Ohana, slated to launch in March after months of regulatory delays held up the carrier's certification.

Meanwhile, in Canada, WestJet last year launched its own regional feeder, Encore, using Q400s. The Calgary-based carrier had eight of the Bombardier turboprops in service at the start of the year and plans to grow to 20 by 2016. Despite the Q400's shrinking backlog—it has fallen 75% in the last five years and stood at 25 at the end of 2013—the Q400's engine aftermarket competition is heating up. P&W-designated overhaul facility Vector Aerospace's overhaul center on Prince Edward Island earned Transport Canada approval to overhaul PW150As. In addition, Vector is opening a PW150A overhaul center in Singapore. The facility, which could be open by year's end, is expected to handle three to four overhauls per month at the outset, rising to nearly 100 per year within five years.

The Singapore shop would be the fourth PW150A facility in the world, and the first in Asia. Two of the others—Vector Aerospace Prince Edward Island and PWC's main overhaul center in Saint Hubert, Quebec, are in Canada. The other, Lufthansa Technik AERO Alzey, is in Germany. The locations make sense based on the geographic distribution of the nearly 900 PW150As in service. North America's 318 in-service engines represent the biggest market, while Europe is close behind, at 284, AWIN Fleets shows. The Asia/Pacific region, with 150, is next. The Singapore facility isn't expected to add PW100 capabilities. PWC has another overhaul shop in Singapore that handles everything from the PW118 through the PW127—one of 10 PWC-authorized shops based around the world that focus on the original PW100 range and their derivatives.