28 Seconds
Part Four: Rules of engagement
Was there a hidden flaw in the rudder system of the Boeing 737? Three years after the crash, the chief investigator suspected the culprit was the valve that moved the rudder. But he had no proof.
[Times photo: Bill Serne]

The investigation plodded along, past the one-year mark, past two years, three years. For Tom Haueter, solving the crash was difficult enough; convincing NTSB board members and dealing with the politics would be even tougher.

Bendix offices, North Hollywood, Calif.

Boeing was developing a gargantuan new plane, the 747, and Ralph Vick was hoping his company would win the contract to build a special valve for it. The valve was similar to the soda can-sized one designed several years earlier for the rudder of the 737.

To pass muster, the 747 valve had to survive a series of tortures.

One test shook the valve like a can of house paint in a mixer. Another moved the valve back and forth 5-million times, to simulate a lifetime of use.

The most brutal test was called thermal shock. The valve was frozen to 40 degrees below zero, then injected with hot fluid. That was to ensure it would still work if a hydraulic pump overheated while the plane was in frigid air at 35,000 feet.

Technicians placed the valve in a freezer the size of a wastebasket and cooled it to 40 below. They flipped a switch and heard the steady whine of the hydraulic pumps, then flipped another switch to inject the piping-hot fluid.

The valve strained, then stuck for a few seconds. It had failed the test.

Vick knew it was a setback, not a catastrophe. His engineers went back to their drawing boards and redesigned the valve. It passed without problems.

* * *

Part Three: Roxie, Trixie and the fat guy Page 2
28 Seconds


© Copyright 2006 St. Petersburg Times. All rights reserved.