Operators of Embraer 170 and 175 regional jets are being instructed to check bracket assemblies on the main landing-gear after an incident in which a crew on approach received an indication that the undercarriage was not locked.

While the event did not result in serious consequences, says the Brazilian civil aviation regulator ANAC, analysis determined that failure could occur in the main-gear locking-stay bracket, owing to the installation of a specific self-locking nut during bracket replacement.

Loss of this self-locking nut could lead to the bracket’s disconnection, and possible uncommanded gear retraction, it adds.

Operators have been ordered, in an urgent ANAC directive dated 21 May, to inspect the bracket assembly and locking nut within the next 50 cycles.

It also requires replacement of particular nuts if they are installed, in accordance with an 18 May service bulletin from Embraer.

Hop unlocked-gear incident-c-BEA

Source: BEA

ANAC has not detailed the incident which spurred the checks, although French investigators are looking into a recent unlocked-gear event on a Hop E170

ANAC’s directive does not disclosed details of the incident which prompted the checks, nor confirmed whether it relates to an occurrence at Toulouse on 11 May.

French investigation authority BEA states that the crew of a Hop E170, arriving from Paris Charles de Gaulle, received indication of an unlocked left-hand main landing-gear during final approach.

BEA says the aircraft proceeded to land on runway 14R where it came to a halt, without further problems. The incident, which involved aircraft F-HBXI, is under investigation.

Embraer declines to comment on the directive.