Los Angeles Times

FAA Calls for Shorter Maintenance Intervals on Some GE Jet Engines

By Jennifer Oldham
Times Staff Writer

August 18, 2006

Prompted by the spectacular explosion earlier this summer of an engine in an unoccupied Boeing 767 parked at Los Angeles International Airport , the Federal Aviation Administration on Thursday ordered airlines to follow a more aggressive maintenance schedule for a widely used General Electric jet engine series.

The order, which will affect up to 800 engines on several aircraft models, came before an independent federal safety board completed its investigation of the LAX incident. The FAA decided to act now, officials said, because new information from the investigation warranted shorter maintenance intervals for some wide-body aircraft engines.

The explosion, on June 2, was similar to two other engine failures in the last six years that occurred after a metal disk that holds fan blades in place spun out of control, destroying the engine. No one was injured.

"There may be a pattern," said Les Dorr Jr., an FAA spokesman. "The additional data made us revisit and shorten the inspection cycle."

The new directive, which goes into effect at the end of the month, will significantly tighten existing engine maintenance schedules, mandating a 70% reduction in the interval between inspections and repairs for the oldest General Electric CF6-80 engines.

For newer engines, there will be an average 40% reduction in the number of permitted takeoffs and landings before they are overhauled. The order requires all engines in this family to be inspected, regardless of usage, by December 2008.

About 1,155 of the General Electric engines are installed on wide-body planes in the U.S. , including on Boeing 747s and 767s, McDonnell Douglas MD-11s and Airbus A300 and A310s. Airlines must remove the massive engines to conduct the required inspection, which involves running electrical current over the disk.

Aviation officials said the engine failure at LAX, which sparked an intense fire that severely damaged the American Airlines Boeing 767 and sent a 50-pound piece of metal flying more than half a mile, resurrected a problem they thought they had fixed.

"We don't take these events very lightly," said Rick Kennedy, a spokesman for Cincinnati-based GE Aviation. "This is a very hazardous event, but a very rare event."

An initial examination of pieces of the disk recovered after the LAX incident found cracks caused by fatigue, according to the National Transportation Safety Board. The board expects to close its investigation into the matter soon, said Paul Schlamm, a board spokesman.

Similar hairline cracks found in metal disks in two other engine explosions prompted the FAA to issue an order in February 2004 requiring airlines to closely inspect those parts in GE CF6-80 engines.

These included a December 2002 incident involving an Air New Zealand 767 engine that failed at 11,000 feet on a flight from Auckland , New Zealand , to Brisbane , Australia . The plane landed safely. In September 2000, an engine on a USAir Boeing 767 exploded and broke apart as mechanics were testing it on the ground at Philadelphia International Airport .

After the USAir incident, the NTSB issued an eight-page safety recommendation to the FAA encouraging stricter maintenance schedules for the GE CF6-80 engines.

"The incident raises safety concerns because, if it had occurred during flight rather than on the ground during maintenance, the airplane might not have been able to maintain safe flight," inspectors wrote.

Aviation safety experts said that regulators should have issued the stricter maintenance requirements sooner, especially given the fact that airlines are requiring greater performance out of airplane engines.

"We're asking more and more of engines. Instead of four engines over ocean water we have two," said Jim Hall, who was acting chairman on the NTSB board when it investigated the USAir engine failure. "So we are going to have to constantly be reviewing and staying on top of the incidents with all these engines."

The Air Transport Assn., a trade group that represents the airlines, said that it worked with the FAA on the new directive. American Airlines said that it had already started inspecting its engines.

"We're well ahead of this game," said Tim Smith, a company spokesman. "Right after this happened, we started a program to begin inspecting our engines in a more aggressive fashion than even the new rules require."

The GE engines affected by the FAA directive were built between 1980 and 2001. In 2001, GE redesigned the disk that holds the fan blades, strengthening areas where the blades fit into the disk, Kennedy said.

Because there have been only three failures of the older engines in 12.5 million aircraft departures, it is difficult for engineers to pin down the cause, he added, saying that failures could occur when tools used to install the disks leave tiny cracks that wear out over years of use.

"When you've had literally thousands of these engines in service for 20 years and three failures in millions of flight hours, from that standpoint the infrequency of it has been one of the challenges," Kennedy said.

The American Airlines engine failed after several mechanics in the cockpit revved it up. Seconds later, the engine exploded, sending parts flying into the wing and puncturing fuel tanks that sparked a fire.

What happened next is captured in a dramatic video taken by a tiny camera mounted on the front of an airport firetruck. Firefighters started fighting the fire as their rig made a 270-degree turn toward the flaming aircraft, spraying so much foam on the blaze that a pilot who took off from the airport afterward said the tarmac looked "like a big bubble bath." Bits of burned composite materials were blowing into the wind hours later.

"It was one of these freak things that just happened with no particular warning," said American Airlines' Smith.