U.S. NTSB investigators are on scene examining damage to the engine of the Southwest Airlines plane in this image released from Philadelphia, Pennsylvania, April 17, 2018.

The Federal Aviation Administration will order airlines to perform more frequent inspections of certain engines after a midair failure on a Southwest flight last month killed a passenger, it said Tuesday.

The FAA will require airlines to by August inspect their CFM56-7B engines' fan blades that have flown 20,000 cycles, or flights. It will also order airlines to keep inspecting these blades every 3,000 flights, or about two years.

A blade on one of the engines powering Flight 1380 from New York to Dallas broke off when the plane was above 30,000 feet. Shrapnel flew, puncturing the fuselage of the Boeing 737-700. A passenger died after she was partly sucked out of a blown-out window, marking the first U.S. airline passenger death from an accident since 2009. It was the first passenger fatality from an accident in Southwest's 47 years of flying.

The FAA issued an "emergency" order on April 20 mandating airlines to inspect CFM56-7B fan blades with 30,000 flights, and complete the inspections within 20 days. That was based on a manufacturer service bulletin, which also will be included in the FAA notice to be published Wednesday, the engine's manufacturer said.

The new order from the FAA will bring its guidance in line with that issued by the engine's maker, CFM International, a joint venture of General Electric and Safran Aircraft Engines of France.

Following Flight 1380, Southwest said it was accelerating its engine inspection program. That inspection timeline will satisfy the new FAA requirements by mid-May, a Southwest spokeswoman said.

While the airline is inspecting fan blades, part of the engine cowling, which covers the engine, was missing after the accident.

"Now, we know that the engine inlet cowling suffered significant damage and lost pieces of that cowling may be responsible for the damage to the fuselage, the wing and the stabilizer," said Southwest COO Mike Van de Ven on a call after posting earnings last week. "And the loss of a single blade inside the engine just shouldn't have caused such dramatic impact."