Aerial Firefighting: Modified Maintenance For Reconfigured Regional Jets

Aerial Firefighter Modifies Maintenance For Reconfigured Regional Jets

In 2011, Neptune Aviation Services deployed a BAe 146—reconfigured as an air tanker—to a major wildland fire, the first time that aircraft type was used for aerial firefighting. 

Today, the Missoula, Montana-based company has modified seven of the former regional jets as air tankers for fire retardant dropping, and, in the process, has been phasing out its remaining seven 1950s-era, propeller-driven P2V Neptunes, originally built for the U.S. Navy as patrol aircraft. At least five of the P2Vs will be retired within two years.

Repurposing the BAe 146 for firefighting has also meant designing maintenance support, which differs substantially from commercial airline operations, says Dan Snyder, Neptune Aviation Services’ chief operating officer. He reports that while its “operational fundamentals and limitations” are the same as they would be for a transport category aircraft in commercial service, the wildland firefighting environment subjects the aircraft to more challenging conditions, requiring more proactive maintenance.

Credit: Neptune Aviation Services

“Aerial firefighting puts additional stress on the airframe, due to a different operational tempo,” Snyder notes. “For example, within a given day, a typical commercial aircraft will fly three or more trips, while an airtanker on a major fire could do as many as 10-12 cycles.”

Each cycle, he explains, involves loading fire retardant, flying to the fire, dropping the retardant and returning to base for more retardant. Loading time can be as little as 15 min., whereas a commercial airliner could spend as much as 1 hr. at a gate between trips. This load/fly/return scenario, Snyder points out, mandates an extremely high level of dispatch reliability, which is largely focused on servicing in the field, under less than ideal conditions.

In fact, upon dispatch, each aircraft is joined at its base of operation by a maintenance crew chief, a second mechanic and a support vehicle. Additional technicians, such as those focusing on engines, electrical systems, avionics and nondestructive testing, are also made available if there is a problem the field staff cannot handle. All field maintenance is overseen and coordinated by the company’s maintenance center in Missoula.

In order to minimize unscheduled field maintenance, Neptune Aviation Services performs all heavy maintenance on its BAe 146 and P2V Neptune fleet in-house when it is not fire season.

“Compared to an airline operation, we put our BAe 146 air tankers through earlier and more frequent scheduled maintenance events, because for 6-7 months of the year, the aircraft can’t be easily called back for depot maintenance,” says Snyder. “We have to project out what needs to be done—earlier than would be typical at an air carrier.”

Those projections, Snyder points out, are based on “experience-based, accumulated knowledge of what is likely to happen” and the specific parts and components that would go with the aircraft support vehicles. He cites as examples tires and brakes, which are high consumption items for the BAe 146 in aerial firefighting.

“The higher-dollar, lower-maintenance items are kept at our main base in Missoula as well as our base at Alamogordo, New Mexico,” he says. “If needed, they will be shipped to the field, either on our own corporate aircraft or via overnight courier service—or counter-to-counter, if we are near an airport with airline service.”

Given the demanding nature of the operations, low consumption of engine lubricating oil is very important, Snyder adds. “We often fly from rural airports where inventories of high-performance-capable (HPC) turbine oil are not available, and resupplying would be very costly. Fortunately, the BAe 146’s Honeywell ALF 502 engines consume almost no oil.”

That, Snyder explains, represents a major operational improvement over the Curtiss-Wright-R3350-powered P2Vs, which consume a large amount of oil. “For the P2Vs, we have to preposition engine oil at the tanker base or stocked on the support vehicles,” he says.

At the same time, keeping the engines clean at field level can be challenging. “Frequent engine washes are required because the airplane is operating at a lower altitude where dust, cinders and other debris are very prevalent.” 

Source: http://aviationweek.com/mro/aerial-firefighter-modifies-maintenance-reconfigured-regional-jets

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