The logo of state-owned Israel Aerospace Industries (IAI), the country’s biggest defense contractor, is seen at its offices next to Ben-Gurion International airport, near Or Yehuda, Feb. 27, 2017. Photo: Reuters / Baz Ratner.

Israel’s aviation regulator has ordered airlines with Boeing Co 737 jets converted to freighters by Israel Aerospace Industries (IAI) to comply with loading restrictions and use additional straps when needed before they can resume flying.

Its directive, published as an emergency airworthiness directive on the European Union Aviation Safety Agency website on Thursday, relates to 47 cargo planes that were grounded this week after IAI found an “apparent irregularity” in the production process of a rigid barrier that separates freight from the cockpit.

Australia’s Qantas Airways Ltd operates four of the planes, while India’s SpiceJet Ltd flies three. The other operators have not been identified publicly.