D) The proper procedures for renting out spare houses.

D）出租备用住房的适当程序。

Southwest and the contractor did not follow proper procedures when replacing the aluminum fuselage skins on 44 planes to eliminate potential cracking.

美国西南航空公司及其承包商对44架客机的铝制机身进行更换，以解决潜在开裂隐患，但是并未遵照适当的程序。

The report advised that Lion Air ensure it follows proper operating procedures to improve its " safety culture and to enable the pilot to make proper decisions."

该报告建议，狮航确保遵循正确的操作程序，以改善其“安全文化，并使飞行员能够做出正确的决定”。

The report advised that Lion Air ensure it follows proper operating procedures to improve its " safety culture and to enable the pilot to make proper decisions" . It also advised the airline keep full documentation about technical problems on flights.

该报告建议，狮航应确保遵守正确的操作程序，以改善其" 安全文化，并使飞行员能够做出正确的决定" 。它还建议航空公司保留有关航行技术问题的完整文件。