The US Federal Aviation Administration has ordered inspections of 1,987 US-registered Boeing 737 Next Generation aircraft after reports of pitch-oscillation events linked to excessive freeplay in the horizontal stabiliser system. The directive covers selected 737-600, 737-700, 737-700C, 737-800, 737-900 and 737-900ER aircraft, but excludes the 737 MAX. It does not ground the affected fleet.
Airworthiness Directive AD 2026-20-14 takes effect on 23 November 2026. Operators must measure freeplay in the stabiliser’s left and right pivot hinges and jackscrew using procedures in Boeing Alert Requirements Bulletin 737-55A1104 RB, dated 12 June 2025.
Inspection results will determine whether operators must carry out further or recurring checks, calculate total stabiliser freeplay, repair components or replace worn parts. Compliance dates follow the schedule in Boeing’s bulletin rather than a single deadline for the entire fleet.
The FAA warned that excessive freeplay left uncorrected could lead to aerodynamic flutter and potentially loss of aircraft control. It estimates the initial measurement will require six labour hours per aircraft, at a cost of $510 each, or about $1.01 million across the US-registered fleet. That estimate excludes additional inspections, repairs and replacement parts.
The final rule follows a proposed directive issued in January. The FAA rejected requests from Canadian North and United Airlines to extend or alter inspection intervals, while retaining the option to consider individual extensions where operators can demonstrate that safety would be maintained.