1997Beat Reporting

NTSB delayed intoducing 737 proposals Boeing fought

Byron Acohido
October 2, 1996
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NTSB delayed introducing 737 proposals Boeing fought

The battery of far-reaching safety improvements for the Boeing 737 rudder unveiled yesterday by the National Transportation Safety Board was first drafted by safety officials in March 1995.

But the proposed safety measures did not surface publicly until 19 months later because Boeing argued they were unjustified, according to sources close to the safety board. If implemented, the measures could cost the company hundreds of millions of dollars.

Boeing continues to oppose many of the measures the board is considering to prevent inadvertent rudder movements from throwing a 737 out of control.

NTSB Chairman Jim Hall said the board will revise the safety measures, following the first public discussion of them yesterday. It will vote in two weeks on whether to ask the Federal Aviation Administration to make the changes mandatory.

If, in the end, the FAA does not approve such changes, the airlines and Boeing won't be required to make modifications.

Boeing spokesman Russ Young contended no safety concerns have emerged in the lengthy investigations into two as-yet unsolved 737 crashes or in a seven-month review of the 737's rudder completed by the FAA last year.

"We've seen nothing in the accident investigations, in the design review conducted by the FAA, or in the service history of the aircraft that would require anything this far-reaching," Young said.

Meanwhile, Boeing officials are expected to take protests directly to to safety-board members that they have been making to board investigators since the 1994 Pittsburgh crash, said sources close to the board.

Boeing chief 737 engineer Jean McGrew said the company will await the final recommendations on proposed rudder system upgrades. "We're not quite clear what the recommendations are going to look like, once the board is finished with them," McGrew said.

The safety board yesterday discussed calling for:

  • Extensively redesigning rudder-system components to make them less prone to sudden, hard twists of the rudder, the vertical tail piece that controls the jet's left-to-right heading. Upgrades would be retrofitted on the entire fleet of 2,800 jets.
  • Limiting the useful life of a crucial hydraulic part called the rudder power control unit (PCU). Dirty hydraulic fluid can jam the unit, resulting in hard rudder twists. The PCU was originally limited to 12,000 flights, but FAA rules were changed to allow "on condition" replacement, meaning airlines can use the unit indefinitely.
  • Establishing new procedures and installing new cockpit instruments to alert pilots to sudden rudder swings.
  • Training pilots how to right a plane suddenly thrown out of control by a hard rudder swing, especially at low altitudes when they may have only a few seconds to make precisely the right maneuvers.
  • Tightening FAA criteria for certifying 737 rudders as safe.

The primary author of the NTSN's recommendations is Greg Phillips, the safety board's top rudder expert. Phillips has spent thousands of hours examining, testing and retesting rudder parts from the 1991 crash of a United Airlines 737 in Colorado Springs and a similar crash of a USAir 737 in Pittsburgh on Sept. 8, 1994.

Sources who work with Phillips, speaking on the condition of anonymity, said he began circulating and promoting much the same set of recommendations six months after the Pittsburgh crash, in March 1995.

A couple of months later, in May 1995, the FAA completed its special review of the 737's control system, underscoring many of the concerns about the rudder raised by Phillips.

Yesterday, Phillips said "ample time" had passed since the completion of the FAA study. "We need to spur those on and get these actions accomplished," Phillips told board member John Goglia.

The draft recommendations received support from relatives of some crash victims.

"Finally, I think these are major recommendations that are long, long overdue," said Gail Dunham, whose former husband, Capt. Hal Green, was killed in the Colorado Springs crash.

Dunham protested the safety board's August 1991 decision not to hold a public hearing on that crash and has tracked 737 rudder issues ever since. She flew from her home in Chicago to be in the audience yesterday.

Recent developments have added urgency to the proposed rudder upgrades.

Pilots are continuing to report 737 flights disrupted by unexpected rudder movements. Boeing's McGrew said Boeing has received reports of more than 20 such cases so far in 1996, continuing a trend of some 50 such cases reported between the Pittsburgh crash and the end of 1995.

Boeing contends most of these reports involve glitches in an automatic rudder control device, called the yaw damper, which can move the rudder only a few degrees.

But records show some jets have recurring problems that routine yaw-damper fixes don't eliminate. That was the case with the jet that crashed in Colorado Springs.

Then, last spring, an Eastwind Airline 737 had at least two mildly disrupted flights in the weeks prior to nearly crashing on June 9 near Richmond, Va. The pilot, Brian Bishop, saved the plane by instinctively using the kind of recovery maneuvers safety officials want to see mandated as training for 737 pilots.

Also pushing the need for rudder upgrades are the results of a recent testing of the PCU removed from the USAir jet that crashed in Pittsburgh. The tests were conducted in an independent lab by a panel of independent experts requested by the safety board's Hall. The results revealed the USAir jet's PCU could jam and cause a hard rudder swing to one side operating with dirty fluid under certain temperature conditions.

Boeing has challenged the expert panel's findings and will be allowed to retest the USAir jet's PCU, with Phillips' watching, at its laboratory in Renton next week.

"If we get different results, then we will have to understand why the results are different," said Boeing's McGrew, adding that additional testing could follow.

McGrew said a proposal is being considered to run the PCU removed from the Eastwind jet after it nearly crashed through Boeing's version of the dirty fluid/temperature test, as well.

Beat Reporting 1997