WASHINGTON (AP) _ The investigation into what caused a Boeing 737 to start an uncommanded roll this week has been hampered because of delays in upgrading equipment in the plane, according to the National Transportation Safety Board.

Jim Hall, the board's chairman, complained Wednesday that the Federal Aviation Administration gave too much lag time in an order to upgrade the flight data recorders in 737s.

He also said the agency had ignored a suggestion to replace old 737 cockpit voice recorders running on a 30-minute continuous loop with newer models that can record two hours straight.

By the time the plane in question had landed, its voice recorder had already recorded over the period when the roll started. Also, its flight data recorder had yet to be upgraded.

``This is not acceptable,'' said Hall, whose board had recommended the two changes.

The jet, flown by Metrojet, US Airways' new discount carrier, experienced ``flight control anomalies'' Tuesday as it cruised at 33,000 feet during a flight from Orlando, Fla., to Hartford, Conn., the board said.

The plane started to bank and the pilots saw that the control wheel had turned left and that the rudder pedals were offset. The rudder, which runs up the back of a plane's tail assembly, moves the nose left and right.

After switching to backup systems, the pilots were able to bring the plane back into level flight and make an emergency landing in Baltimore. None of the 117 people aboard was injured.

The incident occurred one month before the safety board holds a hearing to establish the cause of a 1994 crash in which a newer version of the Boeing 737 suddenly rolled and then spiraled into a ravine in Aliquippa, Pa.

Investigators suspect that the crash of USAir Flight 427, which was about to land in Pittsburgh after a flight from Chicago, was caused by an unexpected turn of the plane's rudder, as well as turbulence from another plane. All 132 aboard were killed.

They may never know for sure, however, because the flight data recorder aboard Flight 427 recorded only 11 pieces of information.

In the aftermath of the crash, the safety board called for the immediate installation of digital recorders on 737s that would log not just 11 basic flight parameters, but also the position of primary flight control surfaces and the cockpit equipment that moves them.

The FAA, however, issued a rule in 1997 giving airlines four years to switch to devices recording anywhere from 17 to 88 parameters. While the FAA order applied to all commercial jets, not just 737s, the Metrojet plane had not been upgraded.

The FAA has yet to require two-hour cockpit voice recorders.

Hall said in a statement that the Metrojet investigation ``is being hampered by the lack of basic aircraft data,'' but the FAA defended its replacement timetable.

``Given the complexity of the fleet and the different parameter upgrades, we think the time we have given them is a reasonable amount of time to accomplish such a large undertaking,'' said FAA spokesman Les Dorr.

The safety board sent a team to Baltimore to retrieve the flight data and cockpit voice recorders aboard the Metrojet plane. Investigators also interviewed the crew and removed the plane's yaw damper coupler, its rudder power control unit, two hydraulic fuel filters and samples of the plane's hydraulic fluid.

While the plane did not have the upgraded flight data and cockpit voice recorders recommended by the safety board, the passengers and flight crew may have benefited from two FAA-mandated safety changes made after the Aliquippa crash.

First, the plane had an updated rudder power control unit, a device that had been redesigned by the Boeing Co. after the USAir crash. Also, the pilots had received mandatory instruction about how to respond to unexpected movement of the aircraft's control surfaces.

FAA officials said the Metrojet pilots credited the training with helping them regain control of their aircraft.