US operators of about 755 Airbus A320 family aircraft have three years to make a modification to prevent an uncommanded nose gear retraction.
The US Federal Aviation Administration (FAA) will issue a new airworthiness directive on 10 July mandating the design changes costing about $12,300 per aircraft, or $9.29 million across the US operator fleet.
The FAA adopted the rule about nine months after proposing the modifications first ordered in 2011 by the European Aviation Safety Agency (EASA).
EASA mandated the same change two years ago after an A320 suffered an uncommanded nose gear retraction upon initiating a taxi.
The investigation concluded that the gear retracted due to a combination of a power interruption to the landing gear control interface unit and an internal hydraulic leak.
The power interruption is common during engine start, but it can lead to an uncommanded retraction if it is combined with the hydraulic leak.
To prevent the gear from retracting, the A320 operators must install a power interruption protection circuit, the FAA says.