By Thomas Kaplan

New York Times News Service

WASHINGTON — The U.S. transportation secretary, Elaine Chao, on Tuesday asked her agency’s internal watchdog to conduct an audit of the Federal Aviation Administration’s certification of the Boeing 737 Max 8.

The FAA’s approval of the 737 Max has come under scrutiny after the crash last week of an Ethiopian Airlines jet, the second deadly crash involving the aircraft in less than five months.

“Safety is the top priority of the department, and all of us are saddened by the fatalities resulting from the recent accidents involving two Boeing 737-MAX 8 aircraft in Indonesia and Ethiopia,” she wrote in a memorandum to Calvin Scovel, inspector general for the Transportation Department. Chao wrote that she was seeking the audit “to help inform the department’s decision-making and the public’s understanding, and to assist the FAA in ensuring that its safety procedures are implemented effectively.”

The FAA was slow to ground the 737 Max as safety regulators around the world took action in response to the crash in Ethiopia, and the agency is facing questions over its role in approving the plane as safe to fly in the first place. The FAA certified the 737 Max 8 in 2017, and one concern after the plane’s grounding is the role that Boeing employees played in the certification process.

For decades, the FAA has relied on outside experts to assist in certifying that aircraft meet safety standards. In 2005, the agency created a program through which manufacturers like Boeing could choose their own employees to act on behalf of the FAA to help certify new aircraft.

The FAA is also facing scrutiny over its decisions that pilots who had flown the plane’s previous version would not need additional flight simulator training for the new jet, or training on the automated flight-control system that is thought to have played a central role in the October crash of a 737 Max in Indonesia.

That system, called MCAS, may also have been a factor in the crash in Ethiopia, though the investigation is ongoing.