WASHINGTON (AP) _ Airlines have been ordered by the Federal Aviation Administration to check takeoff warning alarms on all Boeing 727 jetliners because of questions raised in the investigation of a Delta Air Lines crash last month.

FAA officials said Friday the directive to the airlines for a one-time check of the estimated 1,200 727 jets in domestic operation was ''purely precautionary.''

There is no evidence that the alarm, which warns of a false flap setting, malfunctioned in the Delta plane that crashed Aug. 31 at the Dallas-Fort Worth airport, killing 14 of the 108 people aboard, the officials said.

Anthony Broderick, the FAA's associate administrator for regulation and certification, said checking the alarms on all Boeing 727s was ''not anything other than our own effort to gather data.''

''It shouldn't be read that we have any indication that the flaps were involved in the (Delta) accident,'' he said.

In Seattle, Boeing Co. spokeswoman Liz Reese said the company was unaware of the FAA order. She added that the order is not an unusual action.

Broderick said the action was taken because there have been ''a lot of questions asked'' in connection with the crash and the positioning of the flaps during the takeoff.

Investigators have uncovered conflicting evidence as to whether the flaps were positioned properly prior to the Delta crash. The federal investigation has not yet determined the cause of the accident.

National Transportation Safety Board investigators have said that among the areas being examined is whether the flight crew extended the flap setting as required. If the flaps were not extended for takeoff as required, an alarm should have sounded in the Delta's cockpit, but no such alarm could be heard on the cockpit voice recorder tape.

An aircraft's wing flaps help the plane gain lift and should have been extended 15 degrees when the Delta jet took off.

The lever that controls the flaps in the Delta jet was found in a ''retracted'' position and the flaps on the wing also were found retracted. However, the co-pilot was heard on the cockpit voice recorder tape to acknowledge that the flaps had been set at the 15 degree position.

One theory being examined is that the flap setting might have been called out, but not set properly. Another theory has been that a crew member might have extended the flaps properly prior to takeoff, but at the last second retracted them in a desperate attempt to reduce drag and keep the plane aloft.

The NTSB announced Thursday that an inspection of the three engines of the Boeing 727 found no mechanical failure that could be blamed for the accident.