Grounded Eastwind Jet Is Back In Air -- Investigators Haven't Found Cause Of 737'S Four In-Flight Malfunctions

An Eastwind Airlines Boeing 737 passenger jet, grounded for more than three weeks, was returned to service Monday, with federal authorities still baffled about why a malfunctioning rudder disrupted four recent flights.

The plane could have become the third unsolvable 737 crash on U.S. soil this decade, according to a top federal aviation-safety official.

The Eastwind jet's rudder moved on its own on May 14, June 1 and June 8, throwing the aircraft briefly off course. Each time, several rudder parts were replaced and adjusted, the plane tested and then returned to service. The June 1 and June 8 incidents were previously undisclosed.

A fourth incident on June 9 prompted the National Transportation Safety Board to take the unusual step of grounding plane No. N221US for 22 days.

But examination and testing of rudder parts from the jet, conducted last month by Boeing and its subcontractors with Safety Board oversight, produced no answers. The tests are continuing, said Mike Benson, spokesman for the NTSB.

In frustration, NTSB chairman Jim Hall sent a letter Monday to David Hinson, head of the beleaguered Federal Aviation Administration, comparing the Eastwind incidents to the sudden nose dive of a United Airlines 737 in Colorado Springs on March 3, 1991, and the similar unsolved crash of a USAir 737 in Pittsburgh on Sept. 8, 1994. The two crashes killed all 157 on board.

Hall lambasted Hinson for failing to heed a February 1995 Safety Board recommendation that the FAA order U.S. airlines to install state-of-the-art flight data recorders on all 737s by the end of 1995.

"Under slightly different circumstances, the Eastwind incident could have become the third fatal B-737 upset accident for which there was inadequate flight data recorder information to determine the cause," Hall wrote.

Modern recorders can track hundreds of parameters. The recorders used on most 737s track only engine speed and general direction of travel.

Safety experts, pilots and lawyers pressing suits against Boeing in connection with the Colorado Springs and Pittsburgh crashes say Hall's letter is the boldest official admission to date that the 737's rudder poses a risk that authorities don't fully understand.

Boeing says the 737 is safe

Boeing spokesman Steve Thieme noted that the 737 has an above-average safety record compared with all other models. Since first flying in the mid-1960s, 65 Boeing 737s have been destroyed in accidents, including 25 in the 1990s. It is the world's most popular jet model with more than 2,600 jets having logged more than 60 million flight hours.

"The rudder is not dangerous," Thieme said. "It's perfectly safe."

The NTSB's Benson declined to answer questions about risks posed by the 737's rudder. Hall was unavailable to elaborate on his letter.

The June 9 flight that resulted in the grounding of the Eastwind jet was significant because it occurred under conditions similar to the USAir crash in Pittsburgh.

Eastwind Capt. Brian D. Bishop and First Officer Spencer T. Griffin were trained by USAir under contract for Eastwind, a 10-month-old airline based in Trenton, N.J.

Since the Pittsburgh crash, USAir has been one of the most aggressive airlines in training 737 pilots to recognize and react to inadvertent movements of the rudder, the hinged tail panel on the upright tail section that controls left-to-right direction.

Descending at 5,000 feet and 250 knots into Richmond, Va., Bishop felt a "slight rudder bump" to the right and was about to ask Griffin if he felt it when the plane suddenly rolled to the right. Such a movement is consistent with a right rudder deflection.

In response, Bishop turned his wheel sharply to the left, deploying wing panels called ailerons to roll the plane back to the left. He also stepped on his left rudder pedal but reported that it "felt stiff." Bishop then "stood on" the rudder pedal, according to Hall's letter. Bishop also used asymmetrical engine thrust in an attempt to pull the jet out of its uncommanded right roll.

The pilots began shutting down the autopilot and an automatic rudder adjustment device, called a yaw damper, and regained control of the airplane.

Speed may have prevented crash

Bishop and Griffin may have escaped disaster because they were traveling at 250 knots when the rudder malfunction occurred and reacted quickly using their recent training. USAir pilots Peter Germano and Charles Emmett III had no information that the 737's rudder could move on its own, and no specific training on how to deal with it.

Germano and Emmett were descending at 6,000 feet and 190 knots in calm skies over Pittsburgh, when the USAir jet wobbled, then swerved and rolled left, diving into the ground 23 seconds later. Some investigators believe Germano used right ailerons in an attempt to counter the left roll. But tests subsequently revealed that the ailerons have no ability to counteract the 737's large rudder at speeds of 190 knots or lower.

Pilots have reported hundreds of instances of the 737's rudder moving inadvertently over the past three decades, including more than 50 reports in the 22 months since the Pittsburgh crash.

Boeing contends many of those reports can be explained by yaw damper glitches, which are easily controllable by the pilots, or by encounters with wingtip turbulence from planes flying ahead.

Evidence has been emerging during the course of the NTSB's futile investigations into the Colorado Springs and Pittsburgh crashes that the 737 has fewer safeguards against rudder malfunctions than other jets.

Pilot representatives and some NTSB staffers for months now have been discussing a recommendation calling for Boeing to install a device called a limiter. It would physically prevent the rudder from acute deflections once the aircraft is airborne. But the NTSB has declined to issue the draft recommendation drawn up by its staff investigators.

Some industry observers contend the NTSB and FAA have been slow to address the 737's rudder problems, despite mounting evidence of risk, because of Boeing's stature.