Airbus, for instance, rolled out its Flight Hour Services program in Asia about four years ago. “We can provide everything from line maintenance, component repairs and engineering,” says Reamy. “We have a pool where we can provide on-site stock for the exclusive use of an airline and a pool to supplement the on-site stock and manage the repairs associated with those components.”

Similarly, Moog recently entered into a five-year agreement with AeroTurbine as part of its global support offering. Moog will manage a pool of parts for Boeing 787 and Airbus A350 customers on a power-by-the-hour basis at seven pooling locations around the world. The program guarantees availability to a part anywhere in the world within four hours at a price that Schaefer says is less than the cost of buying the recommended parts.

AeroTurbine will provide the logistics services behind the pool to ensure that airlines get the parts according to their service level agreement. “We and other OEMs need to step up and align ourselves with the needs of the airlines,” says Schaefer. “It's a shift in component maintenance.”

With those shifts as backdrop, there are at least three approaches to inventory availability in the market today.

Managing No-Go

While some very large airlines still manage all of their parts, the most common parts to be owned by an airline are the 500 to 600 that make up a main base kit of “no go/go if” items that are essential to line maintenance. These are parts with very high rates of removal that can't be deferred until a later flight. These are also parts that require a 90% availability, meaning the part is available at the right location 90% of the time.

However, few carriers can afford to put every one of these rotable parts in every location capable of replacing them. Instead, the airlines must determine how many parts are needed to meet anticipated demand plus some safety stock.

That's where service parts management software programs can play a role. “The software has an optimization engine that analyze how many parts you might need to meet demand, and how that number changes based on where you stock them,” says Wodarski of Servigistics. The software, for instance, can take into consideration variables such as changes in flight patterns and utilization rates. It also can make adjustments for an airline flying into a network with a proximate density of airports, such as Newark, Nw York JFK and Philadelphia. “The safety stock in one location that's close enough to the others may satisfy reasonable demand because I can get a part there in time if I need to,” says Wodarski.

Although main base kits are the parts most likely to be owned and managed by an airline, those too can be managed by a pool operator. “We have models to determine how many spare components you should have and determine where to put them to optimize the uptime of the aircraft,” says de Vries. “If they own the main base kit, or lease it from us, we can manage that forward deployed stock and replenish it as soon as they use a component.”

Parts Pooling