Say Additional Monitoring Systems Not Needed

Past problems with the rudder mechanisms on Boeing 737s are receiving attention once again, with the American manufacturer and airlines banding together to protest the US government's plan to require closer monitoring of those systems by 2008.

At issue is the FAA's plan for carriers to update flight data recorders to capture additional information about rudder movement on 737s. Reuters reports the plan is part of an extensive redesign prompted by two 737 accidents in the 1990s.

A 1991 crash in Colorado, and another in Pennsylvania in 1994, resulted in more than 150 fatalities. Investigators pinned the blame for both accidents on uncommanded rudder movements, caused by a mechanical defect. Boeing later redesigned the rudder mechanism based on the NTSB's recommendations.

The Air Transport Association, which represents eight domestic 737 operators, said in a recent report that more than 800 out of approximately 1,180 737s in airline service already meet the basic FAA requirements, with most fitted with the redesigned rudder systems. The rest of the fleet, mostly older aircraft, have been fitted with upgrades to the system, and are scheduled to receive the redesigned rudder assembly by 2010.

The ATA says it is doing all it can to make its 737s as safe as possible -- and while the group supports the added monitoring systems being installed on new 737s on the production line, it says the recorders don't need to be fitted to older planes.

"In view of these ongoing measures, we believe the proposal is unnecessary to ensure the safety of Boeing 737 rudder control systems," ATA officials said in the report.

The FAA estimates the cost of installing monitoring systems at $225 million through 2020 -- more than half of which would be for retrofitted monitoring systems. Airlines say the cost would be closer to $300 million.

Both the FAA and NTSB say more oversight is needed -- regardless of the cost.

"Without more data, neither the FAA nor the NTSB can definitively identify the causes of suspected uncommanded rudder events," the FAA said.

The 737 is the most popular commercial airliner in service today. In addition to the large US fleet, more than 5,000 planes are registered to overseas carriers.

FMI: www.faa.gov, www.boeing.com, www.airlines.org