FAA Requires Inspections of Stabilizers on 1,987 Boeing 737s Before Directive Takes Effect in November
Key Facts
The U.S. Federal Aviation Administration issued final Airworthiness Directive No. 2026-20-14, affecting 1,987 U.S.-registered Boeing 737-600, 737-700, 737-700C, 737-800, 737-900 and 737-900ER aircraft. The directive takes effect on November 23, 2026, according to the agency’s publication in the Federal Register. The decision followed reports from operators of pitch oscillation events, which the agency linked to excessive clearance in the horizontal stabilizer. The FAA said the condition, if not addressed, could lead to aerodynamic flutter that could result in loss of control of the aircraft. The directive calls for measuring clearance at the stabilizer pivot hinges and jackscrew, then carrying out the applicable actions based on the measurement results. Boeing’s service bulletin sets the compliance times and required actions, with the directive’s effective date to be used as the reference when the bulletin refers to its original issue date.
The agency explains that November 23 is the date the directive takes effect, while the deadlines for completing inspections are tied to Boeing’s requirements bulletin and the actions it specifies for each case. Operators must therefore apply the compliance times in the bulletin, using the effective date as the reference when the bulletin relies on its original issue date. The inspection includes measuring clearance at the two horizontal stabilizer pivot hinges, as well as the jackscrew that moves it. The measurements determine whether the aircraft needs additional actions, repairs or replacement of worn parts. Some cases may also involve subsequent repetitive inspections, but the timing depends on the applicable case and measurement results. The directive’s effective date alone therefore does not represent a uniform deadline for completing every initial inspection.
The FAA estimated that the initial measurement would take 6 labor hours per aircraft, at a labor rate of 85 dollars per hour, putting the inspection cost at 510 dollars per aircraft. The agency calculated the total cost of the initial inspection for U.S. operators at 1,013,370 dollars. The agency also estimated one labor hour for repair or replacement of worn parts, at a cost of 85 dollars per aircraft when needed. It said, however, that it lacked definitive data to estimate the cost of spare parts and could not determine how many aircraft might require parts replacement. The estimated labor cost for repairs is therefore defined, while the parts bill remains uncertain. The FAA said the minor editorial changes it made to the final directive do not increase the economic burden on any operator.
The FAA published the proposed directive on January 9, 2026, corrected it on January 16, and set February 23 as the deadline for receiving comments. The agency said it received comments from five parties supporting the proposal without changes, including the International Federation of Air Line Pilots’ Associations, Boeing and two individuals. It also received additional comments from four parties, including Alaska Airlines, Aviation Partners Boeing, Canadian North and United Airlines. Canadian North requested an extension of the initial inspection deadline from 12 to 36 months after the June 12, 2025 issue date of Boeing’s service bulletin. The FAA said it rejected the request because the compliance times set out in the bulletin ensure an acceptable level of safety for the fleet, and adopted the directive as proposed with minor editorial changes.
In its comment, Alaska Airlines said one pathway includes a repetitive inspection within 3,100 flight hours or within 6 months of the last inspection, and the initial measurement result may call for a second repetitive inspection. These intervals apply to the specific case in the bulletin’s table and do not represent a general schedule for all affected aircraft. The FAA rejected an exemption from the repetitive inspection requested by the company, but said operators may conduct the inspection early and then carry out the repair or replacement as soon as possible during the same maintenance period. After repair or replacement, an inspection is required to verify that the clearance values remain within Level 1 limits before the aircraft returns to service. The agency also said it would consider requests to extend compliance deadlines if operators provide sufficient data showing that the new deadline would provide an acceptable level of safety.
United Airlines also asked the agency to credit an earlier inspection conducted under a Boeing service letter dated May 27, 2022, noting that its work instructions matched those in the inspection bulletin. The FAA responded that the bulletin already provides some relief for aircraft previously inspected using acceptable procedures. Canadian North’s request, meanwhile, was based on extending the deadline from 12 to 36 months after Boeing’s service bulletin issue date, but the agency retained the compliance times in the bulletin. The FAA’s position allows it to consider an individual extension request if the operator supports it with sufficient data, the agency said. The final directive takes effect on November 23, 2026, while inspection and repair work follows the deadlines set out in Boeing’s service bulletin according to the applicable case.