Boeing, FAA back safety of 737 despite redesign order

Are Boeing 737s safe or not?

Both the Federal Aviation Administration (FAA) and Boeing yesterday maintained they are very safe, among the safest airliners ever built.

But in ordering the redesign of a problematic rudder mechanism implicated in two crashes in the 1990s, the FAA is saying the 737 needs to be safer, and Boeing said its engineers will make it safer - even if they don't think there is a deficiency.

The fixes ordered by the FAA won't be completed any sooner than 2006 - 15 years after the first crash. The agency and Boeing both contend that's OK because the change goes beyond an earlier remedy that addressed the crash causes.

"We are not fixing a safety problem with this enhancement we are making," insisted Allen Bailey, the Boeing engineer in charge of 737 safety certification.

Boeing's long-running defense of its airplane, reiterated at a Seattle news conference yesterday, is of little comfort to at least some relatives of those killed.

Jon Hamley, whose wife was killed in 1994, argued that a safe airplane wouldn't need a redesign.

If the 737 is safe, "Why are they doing this?" asked Hamley, whose wife, Sarah, was a flight attendant for USAir when Flight 427 crashed near Pittsburgh. Despite the action Boeing and the FAA are taking, he said, Boeing "hasn't admitted, `Yeah, our rudder is screwed up. We're going back to the drawing board.' "

In Washington, D.C., where the FAA announced its plan to mandate replacement of the rudder mechanism on the most popular airliner in history, there was some agreement with Boeing's point of view.

"Any data shows the 737 is one of the safest airplanes in the world today," said John Hickey, manager of the Renton-based Transport Airplane Directorate of the FAA. "All the previous design fixes have corrected known deficiencies."

Yet, a few breaths later Hickey said: "The redesign is the right safety solution for that airplane."

Solution to what problem? The FAA yesterday released the findings of a yearlong engineering study, which had been recommended by the National Transportation Safety Board (NTSB) after it determined rudder malfunctions likely caused the two 737 crashes.

The 737 Flight Control Engineering Test and Evaluation Board, led by the FAA and involving Boeing and outside engineers not previously familiar with the rudder system, found:

The 737's rudder system is susceptible to a number of failures and jams that can cause unintended rudder movement, some of which could lead to a catastrophic result.

Recently developed steps for pilots faced with rudder problems are too complicated, and pilots have not received enough training to handle them effectively.

Maintenance procedures are insufficient to find hidden problems in the rudder system.

Following most of the engineering board's recommendations, the FAA said it will issue simplified pilot procedures, order more training and change maintenance standards in the coming months.

And next summer, the agency plans to issue an airworthiness directive ordering airlines to implement the design change Boeing is working on.

That change will involve replacing a single valve that moves the rudder with two independent valves, either one of which can take over if the other fails. The 737 is the only large commercial jet with a rudder controlled by a single hydraulic valve.

Boeing estimates the new design will be tested and certified by 2003, at which time the company will begin installing it in new airplanes and provide 737 operators with retrofit kits. About 3,400 737s are in service worldwide, more than 1,300 of them in the U.S. The FAA's order only applies to U.S.-registered planes.

The FAA's Hickey said U.S. airlines will probably have five years to make the change, allowing them to do so as planes come due for routine overhauls. When the clock starts ticking has not been determined.

That means the design change would be installed in the entire U.S. fleet no sooner than 2006 - 15 years after the crash of United Airlines Flight 585 in Colorado Springs, which killed 25 people in 1991, and 12 years after the USAir crash, which killed 132 people. Both planes suddenly spiraled to the ground during landing approaches.

The five years it will take to outfit the fleet speaks to the FAA's and Boeing's belief that the chances of future rudder malfunctions are very remote. It also speaks to the complexity of the task.

"Redesigning a flight-control system is not a trivial matter," said Hickey. "It is a very complicated system. It doesn't happen overnight."

Thomas Demetrio, a Chicago lawyer, last year helped the family of Marshall Berkman, a Pennsylvania manufacturing executive killed in the Pittsburgh crash, win a record $25.2 million settlement from Boeing and its rudder-valve supplier, Parker Hannifin.

"To give them five years to fix it is outrageous," Demetrio said. "If the 737 is so airworthy and so safe . . . then why are they doing all of this?"

Said Tom Ellis, an investigator for aviation lawyer Donald Nolan: "This may sound drastic, but I honestly believe they should do with the 737s what they did with the Concorde and ground the fleet until they get a new design and implement the new design.

"But they'll never do that because of the opposition of the airlines and how much the U.S. carriers are dependent on this aircraft for their livelihood," Ellis said.

Whatever the timeline, the new design should satisfy the NTSB's contention that the present rudder mechanism is not "reliably redundant."

In the case of Flight 427, the NTSB concluded last year, "the rudder surface most likely deflected in a direction opposite to that commanded by the pilots as a result of a jam of the main rudder power control unit servo valve. . . ."

Boeing and the FAA say a previous airworthiness directive involving redesign of that single valve solved the problem that probably caused the crashes. Replacing one complicated valve with two simpler ones, however, will make it impossible for the system to malfunction in any of the ways uncovered by the engineering board, they say.

That said, to this day Boeing contends the present single-valve design, essentially a valve inside a valve, is reliably redundant.

"The current system has absolute redundancy in it," Bailey said. "What we are talking about is ensuring the reliability of that redundancy."

That assurance will likely cost more than $200 million. Boeing will have to negotiate what financial burden, if any, it shares with 737 operators. Southwest Airlines, the carrier with the most 737s - 333 in the fleet and growing - said a likely outcome would have Boeing paying for the hardware and the airline paying for the labor.

Chuck Taylor's phone number is 206-464-2465. His e-mail address is

Seattle Times reporters Byron Acohido and Kyung Song contributed to this story.


Rudder on the web

A Boeing computer animation demonstrating the planned 737 rudder redesign is available on