SpiceJet has returned three Boeing 737-700 freighters to service following resolution work provided by Israel Aerospace Industries (IAI).

“We wish to update that these three grounded B737 freighter aircraft shall return to our operations effective December 23, 2019 basis the resolution provided by IAI,” says the company in a stock exchange filing.

The airline had grounded the three jets in mid December following the advice of IAI, which advised operators of its converted freighters, of which 47 were delivered, not to operate them.

On 12 December, it was reported that IAI detected an “apparent irregularity” in some of its converted Boeing 737 freighters.

The irregularity pertained to a cargo door installed during conversion from a passenger jet to a freighter. This is a rigid barrier that serves as an additional safety feature to separate the cockpit from the cargo and is not critical to flight safety.

IAI stressed that the rigid barrier does not affect flight under normal conditions. The barrier is designed to restrain the main deck cargo load, particularly during rapid deceleration. Rigid barriers are intended to replace nets and allow the space normally reserved for stretching of these nets to be re-allocated.

IAI’s directive says a manufacturing “non-compliance” could “seriously affect” the ability of the rigid barrier to meet the demands of an emergency landing.

The three 737-700 freighters are registered VT-SFB, -SFD and –SFE and were delivered to the airline between 2018 and 2019. The trio were originally in service with Xiamen Airlines.