UK investigators have determined that a maintenance error resulted in a British Airways Boeing 747-400’s having to land without deploying either of its wing main-gear assemblies.

The aircraft (G-CIVX) had departed London Heathrow on 30 January this year, its first flight since a scheduled A-check.

This check included replacement of the landing-gear control module.

When such a replacement is carried out, maintenance manual requirements include fitting a rig pin in the undercarriage selector valve quadrant through which the landing-gear is controlled from the handle in the cockpit.

But the UK Air Accidents Investigation Branch states that the rig pin was omitted.

It says this occurred through a combination of deficiencies in the operator’s task-card system, inadequate handover between engineering shifts, and the distraction of an engineer – who had noticed the rig pin’s absence and, concerned about possibly being injured, had taken an overdue break.

The incorrect rigging during the module replacement subsequently caused the landing-gear lever to jam after the crew retracted the undercarriage. It would not move to the ‘off’ position, which depressurises the hydraulic system.

Having opted to return to Heathrow, the crew lowered the nose-gear and the two fuselage main-gear assemblies using the alternate gear-extension procedure.

BA has since introduced additional rig pin processes, reinforced handover procedures and provided supplementary task-card training.

Source: Cirium Dashboard