Finding a real-world depiction of what Bombardier CRJ100/200 maintenance spending is expected to look like in the next decade is a snap. Head to the local playground and look for a slide.

Aviation Week’s Commercial Fleet and MRO Forecast shows MRO spending on the best-selling regional jets ever built (Bombardier delivered 935 CRJ100s/200s) will be flat for two years on each end of the 2013-22 time frame, with six years of steady decline connecting the top and bottom plateaus.

Total global spending for the 10 years ending in 2022 is expected to be just more than $7.3 billion. About 36% of the output—$2.7 billion—is evenly divided between this year and next.

The downward slope begins in 2015, when the forecast projects $1.2 billion in spending, followed by $982 million in 2016. By 2020, annual spending is slated to be down to $305 million, followed by two years of sub-$200 million spending to round out the decade.

The gradual drop in 50-seat CRJ maintenance spending is no surprise; fleets heading rapidly for retirement are not great long-term aftermarket spending generators. The biggest regional jet (RJ) users­—namely North American mainline carriers and their regional partners—are moving away from smaller RJs, and quickly. Delta Air Lines’ new pilot agreement, for instance, cuts the maximum number of 50-seat RJs to 125 from 350, while caps on larger RJs were boosted.

Aviation Week data show about 830 50-seat CRJs in service or storage. That figure is expected to dip below 600 by 2018 and fall to 100 or so in 2022.

The small RJ’s demise is no mystery. The spike in per-gallon jet fuel prices to $3.90 in June 2008 from $2 in April 2007 forced airlines to take fresh looks at costs. They responded with a capacity-tightening strategy that includes replacing their smallest jets with larger aircraft—or nothing at all.

New Limits

While fuel prices dropped, they have not been below $2.50 since 2010. Therefore, Delta CEO Richard Anderson says that 50-seaters are no longer economical beyond stage lengths of 300-350 mi. In practical terms, that means fewer Atlanta-Albany, N.Y. routes (852 mi.) and more Atlanta-Albany, Ga. ones (146 mi.).

Interestingly, the changes are not hitting all sizes of airports uniformly.

A recent Massachusetts Institute of Technology study concluded that U.S. medium-hub airports have been hit hardest by the 50-seat RJ’s demise. In 2012, medium hubs accounted for about 300,000 departures of RJs with 50 or fewer seats—less than half of 2007’s total. Small hubs, by contrast, still had about 300,000 departures in 2012, or two-thirds of their 2007 totals. Non-hubs had the fewest such departures in 2012—just under 300,000—but actually gained some compared to 2007.

One explanation for why medium hubs have been hit so hard: the bigger the market, the easier it is to replace 50-seaters with larger aircraft. However, the study notes, the replacement trend is not one-for-one. Instead, a larger jet is flying where two 50-seaters once did, accomplishing the airlines’ goal of keeping capacity in check.

Shifts in economics and pilot scope clauses are opening up new opportunities for larger RJs, including Bombardier’s CRJ700s, -900s and -1000s. Aviation Week’s fleet database shows 357 CRJ700s, 271 -900s and 45 -1000s in service; the aggregate total is projected to be about the same in 10 years, with new -900s and a few more -1000s canceling out retiring -700s.

The steady fleet count creates a similarly predictable—and potentially lucrative—MRO market. Aviation Week’s commercial fleet and MRO forecast projects about $11.6 billion in total aftermarket spending on the larger CRJs over the next 10 years.

Spending dips below $1 billion only once: 2013’s $931 million. The top-end year is projected to be 2020, at $1.4 billion.

Taken together, the current-generation CRJ’s MRO market is projected to be $19 billion in the next decade. While it is clear that 50-seaters are heading for the bone yards and the -700s and -900s are placeholders for new-generation RJs—including the revamped Embraer ERJs, the all-new Mitsubishi Regional Jet and the larger Bombardier CSeries—the near term still offers notable aftermarket opportunity.

Possible Opportunities

Some MROs are betting on this hidden gem. Timco Aviation Services, for instance, established a CRJ line and heavy maintenance facility at Cincinnati in October 2012.

As smaller CRJs—including some relatively young ones—head for storage, some industry officials suggest the shift of a few variables could create opportunities for the 50-seaters.

If fuel prices fall low enough, rock-bottom acquisition costs could make 50-seaters ideal for stopgap lift or an adventurous hyper-regional airline.

“You can . . . imagine an environment where everyone is trying to get large regional jets and, as a result, large regional lift becomes expensive and 50-seat regional lift becomes inexpensive,” said Scott Kirby, US Airways president, this spring.

“We’re agnostic about whether we have 50-seaters or larger regional jets. It’s all about the economics. Today, the economics of large regional jets are better, but five years from now, that might be different.”

Globally, there is some hope that emerging markets in Africa, Asia and the Middle East could find use for some displaced CRJs. But those opportunities will pale in comparison to the regional jet’s heyday during the mid-2000s in North America.

Overhaul Requirements

CRJs have several current airworthiness directives (AD) calling for part or component swaps. Transport Canada (TC) AD CF-2013-12, issued in April, calls for inspection and eventual replacement of CRJ100/200/440 pilot-side rudder pedal tubes. Deadlines vary based on the aircraft’s service history; those with 37,000 or more cycles require swaps within 300 cycles.

A February directive (CF-2013-03) orders initial replacement of CRJ700/900/1000s’ left- and right-side elevator bell-crank supports at designated flight-hour limits depending on the aircraft time in service. The process must be repeated every 20,000 flight hours following the initial swap.

In January 2012, TC issued CF 2012-06, requiring CRJ operators to install new sensing elements in the main landing-gear wheel well and the over-wing area, protective blankets on the upper surface of the wing box and fuel tubes, and protective shields on the rudder quadrant support-beam in the aft equipment compartment. The fixes, which help ensure high-pressure-duct bleed air leaks are detected quickly, must be done by Feb. 9, 2014, or within 6,600 flight hours, whichever comes first.