Airliner Repair, 24/7
Boeing's traveling fix-it team has one goal: Get it airborne.
- By Stephen Joiner
- Air & Space magazine, November 2008
Rick Turnbaugh / Boeing Creative Services
(Page 5 of 6)
Still, damaged aircraft rarely go back together exactly as they rolled out of the factory. Change—as routine as replacing a stripped bolt with an oversized substitute—happens. “Any time you change the configuration of anything in the structure, you have to document it,” Craig Oppedal says. Every deviation from “drawing config,” the blueprint gospel of an aircraft as originally constructed, is subjected to his scrutiny and triggers a Field Rework Record (FRR). Oppedal’s been on AOG repairs that produced just a few FRRs, and others that resulted in 280. But there’s always something. All FRRs become part of the voluminous documentation that follows an airliner around for life.
The replacement pressure bulkhead has no deviations to document. In 1978, a Boeing AOG team repaired the bulkhead of a Japan Airlines 747 damaged in a tail-drag incident. Seven years later, the repair failed in flight, resulting in an explosive depressurization that tore off the vertical fin and severed all hydraulics systems. Some 30 minutes later, the aircraft slammed into a mountainside; 520 people died in the second worst airline disaster in history. Investigators determined that the AOG repair did not comply with Boeing’s own Structural Repair Manual. Boeing accepted 80 percent of the liability for the crash, while JAL accepted the remainder for neglecting signs that the repaired bulkhead was weakening.
Every night at 7:30, the day crew logs out and the second shift “ties in.” The playlist mellows, and reassembly continues around the clock. Mangled skin is replaced with new aluminum. The new bulkhead is sealed into the 48 section, fuselage segments are reunited, and the vertical fin is dropped back into its slot.
The critical task of reconnecting the control cables and hydraulics that operate the tail’s rudder and elevators belongs to rigger Randy Pratt. He’s required to adjust the 175-foot tungsten steel cables back to Boeing factory specs to produce the flying characteristics the airplane came off the production line with—no matter how far out of whack the airline flew it. “They’ll say ‘Hey, what did you do to my airplane?’ ” Pratt tells me. Adjustments made for the flight preferences of particular pilots, or an accumulation of skin patches that skew the airplane’s aerodynamics, produce differences from manufacturer’s suggested settings. Soon after recouping their airplane, airline mechanics typically set about undoing Pratt’s precision work, adjusting cables and neutral positions to customize control to taste.
On day 18 the airplane is towed out into a squall of rain and snow. “We’ve got a page and a half of functional tests to do,” Mike Carpenter says. Control surfaces aft of the separation point are actuated and electrical components energized. The auxiliary power unit then over-pressurizes the fuselage for the “high-blow” test. Made of expandable, credit-card-thin aluminum, the pressure bulkhead in normal service holds seven pounds per square inch. In addition to testing the join ring seal, the 12-psi high-blow stretches the new bulkhead’s elasticity nearly to its limit. The test also results in instant break-in: Stretching and fatigue during routine lower pressurizations are thus minimized.
It’s day 20, and make-readies continue down to the last minute. At a sit-down with airline officials, every item on the survey list is verbally closed out. Mike Carpenter and Paul Amrine sign their names to a document attesting that the aircraft has been repaired to the standards of the Boeing Company and the Federal Aviation Administration (FAA standards are published online; the AOG team references them constantly) and is ready to return to service. Then the whole movable factory packs up.
Like now. “We’ve literally had passengers with tickets in their hands looking out the window of the gate at us as we were boxing up our equipment to leave,” Jim Testin says.
Corporate carriers with three-figure fleets and thousands of flights daily rely on Boeing’s AOG teams to discreetly get airplanes flying again, ASAP. But its real clients show up in ones and twos, clutching boarding passes and tripping over shoelaces untied for security checks. “There’s a tremendous effort that’s put forth on behalf of the traveling public,” Testin told me back in Everett, “to make these planes the safest in the world. If an airline calls, we’ll have somebody there.”