The US FAA has ordered a second round of inspections on elevator tabs for Boeing 737 Next Generation aircraft after a second in-flight vibration incident.
The new checks apply to 737s with line numbers between 2508 and 2707, a Boeing spokeswoman says. Aircraft flying extended twin-engine operations (ETOPS) missions must complete the inspections within six days, but all others have 12 days.
Boeing has clarified the instructions for the inspection criteria since another 737NG operator experienced an in-flight vibration event on 2 April.
The elevator tab for the same aircraft had previously been inspected in the first round of checks ordered after 15 March, Boeing says.
In that incident, a 737NG reportedly operated by Ryanair was forced to land in Brussels after severe elevator vibration damaged the tab control system.
According to Boeing, the vibration is caused by failed mounting lugs, which were provided by a supplier using incorrect tooling.