Web posted on: Thursday, July 02, 1998 5:17:37 PM EDT

WASHINGTON (CNN) -- The Federal Aviation Administration has ordered engine inspections on all Boeing 737-700 and -800 series aircraft following two inflight engine shutdowns on June 26.

The problems, on Russian Transaero Airlines and Norwegian Braathens Airlines, occurred in the engine accessory gearboxes of the aircraft. The gearshafts "failed due to inadequate fatigue capability caused by high stresses introduced during the manufacturing process," the FAA said. There were no injuries, and the manufacturer -- CFM International -- has changed its process.

The FAA has ordered all No. 2 engines on the aircraft to be inspected immediately before further flight. The agency also called for inspections on the No. 1 engines the day following the No. 2 engine's inspection, and for both engines every other day until any defective engine starter gearshafts can be replaced.

The order requires the airlines to inspect the gearbox magnetic chip detectors, a process which takes about a half-hour at minimal cost. If the magnetic chip detector indicates signs of abnormal wear, the airline must replace the gearshaft, which takes about 12 hours at a cost of $10,295 per engine.

The replacements must be completed by August 1 (or 350 hours in service) for engine No. 2 and September 1 (or 725 hours in service) for engine No. 1.

The inspection order affects 94 engines on 47 aircraft worldwide; 46 of those engines are on 23 planes registered in the United States. The U.S. operators are Continental Airlines (9 aircraft), Southwest Airlines (13 aircraft) and Eastwind Airlines (1 aircraft).

The accessory gearbox is used to start the engine but once ignition occurs, the gearbox takes off engine power to run the plane's hydraulic and electrical systems.

Reuters Limited contributed to this report.