Airlines soon face a nearly $30 million bill to replace seat-locking parts on 1,281 Boeing 737s in US registry, the Federal Aviation Administration says.
The issue is common to all 737 variants introduced since the 737-100, according to the FAA's notice of proposed rulemaking, which will be published in the Federal Register on 16 January.
A seat track attachment is "structurally deficient" and could fail in an emergency landing if forward loads exceed 9gs, the notice says.
Replacing and modifying the components across the fleet will cost up to $29.1 million, the FAA says.
The notice will be open for public comment for several weeks. The FAA could then issue an airworthiness directive requiring the changes.