Investigators have disclosed that an attempt to lower an Airbus A330-200's undercarriage by free-fall failed because the condition of key actuator components had deteriorated.

The aircraft – operated by Turkish carrier Onur Air on behalf of Saudia – had been flying from Medina to Dhaka on 21 May last year but, 22min after take-off, suffered a hydraulic malfunction while in cruise at 37,000ft.

Saudi Arabia's Aviation Investigation Bureau, in an annual summary document, says the green hydraulic system showed a low-level reservoir warning, and the crew diverted to Jeddah.

The aircraft held for 2h to burn fuel and, after entering the initial approach, the crew attempted free-fall landing-gear extension.

But cockpit indicators suggested the nose-gear had not deployed, and two low passes were carried out over runway 16C to enable ground observers to check its status.

"Neither the control tower nor ground staff were able to confirm the nose-gear extension," says the bureau.

Some 90min after starting the first approach, the crew declared an emergency and the aircraft touched down on runway 34R with its nose-gear retracted, rolling for 1,350m before its engines and fuselage underside contacted the ground.

The jet stopped about 700m from the end of the runway, and 5m to the right of the centreline. Its crew subsequently activated the fire-extinguisher for the right-hand Rolls-Royce Trent 700 powerplant.

Fifty-two passengers received minor injuries, and one suffered serious injuries, during the evacuation, carried out through four doors – three left and one right, although the right-hand exit was not used.

Inspection of the hydraulic manifold and free-fall rotary actuator showed that two motors had "deteriorated magnets coating and bonding", says the probe, which led to the failure of the system to operate.

Investigators subsequently requested that operators perform a free-fall system check.

Cirium's Fleets Analyzer lists the aircraft involved (TC-OCH) as having originally been delivered to Emirates in 2001 before being transferred to Onur Air in 2016.

Source: Cirium Dashboard