A High-Maintenance Fix
The B-2 stealth bomber, with its boomerang shape and rubber-like skin, is a marvel of high-tech engineering, capable of sneaking undetected across hostile territories.
And the special coating that makes the $2.1-billion aircraft nearly invisible to radar is a big maintenance headache: It takes technicians days to gingerly reapply the coating each time a body panel is removed to allow access to the jet’s innards.
“It’s not like painting a house,” said Ronald Sugar, chairman and chief executive of the B-2’s manufacturer, Century City-based Northrop Grumman Corp.
Hoping to speed things up, Northrop has taken a page out of the Earl Scheib handbook on painting by coming up with a new formula and an automated application system that could significantly slash the amount of time the aircraft is unavailable for flight.
In some cases, the new coating may allow repairs to be completed “in minutes instead of days,” said Duke Dufresne, the Northrop vice president who heads the B-2 program.
Neither Northrop nor the Air Force will say it, but aerospace industry analysts think the new coating also increases the ability of the B-2 to escape detection by radar.
Although it has been praised for its stealth capabilities, the bomber also has been maligned for the extensive maintenance it requires.
“It’s been hard to keep them flying,” said Christopher Bolkcom, a military aircraft analyst for the Congressional Research Service.
A B-2, according to an Air Force report in 2001, spent about 70 hours on the ground undergoing maintenance for each hour in the air. And in some years, only about 40% of the B-2 fleet was ready to fly a mission at any given time.
The Pentagon spends $300 million to $400 million a year upgrading, maintaining and overhauling B-2s, with most of the work done at Northrop’s plant in Palmdale, where about 1,100 people work on the program.
Although it’s costly to maintain, there’s nothing else in the world like the stealth bomber. With its radar-evading features, it’s likely to spearhead the attack in what the Air Force calls “suppression of enemy air defenses.”
At the outset of the war in Iraq last year, the B-2 was one of the first aircraft to drop bombs, destroying radar installations and defense systems.
This cleared the way for other bombers and fighter jets to begin attacking Iraqi military forces and facilities.
The stealth capability is derived from the way the aircraft is shaped -- basically a flying wing lacking conventional fuselage and tail -- and by the smooth skin that covers any gaps that could reflect radar waves. The skin has a rubber-like feel and electromagnetic properties. Exactly what it’s made of or how it works is top secret.
Radar systems function much like canes used by blind people to detect what might be ahead of them. A radio wave travels through the air and when it hits an object, it bounces back to its emitter, signaling the existence of the object.
Unlike the jagged shape of the F-117 stealth fighter, which deflects radar waves in various directions, the B-2’s coating actually absorbs the waves. Analysts believe that with the coating, the B-2 appears on the radar screen as an object the size of a tennis ball rather than an aircraft with a wingspan similar to that of a 747 jumbo jet.
But that coating must be stripped off each time maintenance or repair is performed, then reapplied and allowed to cure before the aircraft can be returned to service. About 3,000 feet of tape is used to fill any gaps.
Often the cured coating must then be hand polished to the required thickness, which is measured in thousandths of an inch. Any variation reduces the ability to absorb the radar waves.
Northrop engineers and chemists came up with the formula for the new coating after nearly a decade of research. It is called “alternate high-frequency material” and is applied by robotic paint sprayers.
With the new paint and automated spraying process, technicians no longer need to deal with the coating or the tape. B-2 maintenance personnel are able to pop open a panel, repair wiring or electronic components, then screw the panel back on -- the standard procedure for most aircraft.
The Air Force believes that the new coating eventually will increase the B-2 fleet’s so-called mission-capable rate from about 40% to as high as 60%.
In the past, about half of major maintenance time was spent stripping off the special coating and then reapplying a new coat. Now, once all the preparation work is complete, four robotic arms, resembling large dental probes, can spray around the clock for 12 days, stopping only for a layer to cure.
The exact number of coats applied is top secret; some analysts believe it is several dozen. But even with all the layers, the coating doesn’t measure much more than the thickness of a human hair.
The first bomber with the new coating, the Spirit of Washington, is expected to go back into service later this summer at Whitman Air Force Base in Missouri, where all the stealth bombers are based. Northrop executives recently allowed a reporter to view the freshly painted aircraft at its Palmdale facility.
Since the first B-2 was unveiled at the plant in 1989, few outside the B-2 program have been allowed to see the aircraft up close.
The Spirit of Washington is getting the finishing touches of a major overhaul at Palmdale, a once-in-every-seven-years operation that can last 14 months. It includes inspections and upgrades to electronic, wiring and avionic systems.
One of the distinct features of the B-2 has been its smooth, almost organic-like skin, with all of the joints and rivets covered. The new coating has changed the look.
At Palmdale, Northrop engineers recently proudly pointed out how the panels and the rivets on the surface of the Spirit of Washington’s wings, although freshly coated, were clearly visible. In curing a maintenance headache, Northrop has made this most high-tech of aircraft look more like its low-tech cousins.
