FAA Orders Engine Pin Swaps to Keep Pistons From Misbehaving
Published Date: 11/9/2026
Rule
Summary
If you own or work with Lycoming O-235, O-540, or IO-540 engines, listen up! The FAA is updating rules to replace certain piston pins that could cause engine trouble, plus check oil parts for metal bits. These changes start November 24, 2026, and might cost some time and money but keep your engines safe and sound.
Analyzed Economic Effects
6 provisions identified: 1 benefits, 4 costs, 1 mixed.
Mandatory piston-pin replacement
If you own or operate Lycoming engines listed in the AD with piston pin P/N LW-13445 manufactured between January 7, 2021 and December 15, 2025 (or if the manufacture date is unknown), you must replace the affected piston pin with a part eligible for installation. The AD requires replacement per Lycoming MSB 667A and may require replacement before further flight if metal particulates are found.
Estimated compliance cost and fleet size
The FAA estimates this AD affects 957 engines on U.S.-registered airplanes and estimates a per-engine compliance cost of $4,325 (25 work-hours × $85/hour = $2,125 labor plus $2,200 parts), for a total U.S. operator cost of $4,139,025. The FAA notes some costs may be covered under warranty by the manufacturer.
Immediate oil change and inspection deadline
Effective November 24, 2026, Group 1 and Group 2 engines (except Group 2 engines with ≥150 hours time-in-service (TIS) as of that date) must have an oil change and a visual inspection of the engine oil filter, oil pressure screen, and oil suction screen for metal particulates within 5 hours TIS after the effective date. If metal particulates are found, the AD requires replacement of the affected piston pin before further flight.
Deadlines for piston-pin replacement by engine group
The AD sets group-specific replacement deadlines: Group 2 engines with ≥150 hours TIS as of November 24, 2026 must have affected piston pins replaced before further flight; Group 2 engines with <150 hours must replace within 25 hours TIS after November 24, 2026 or before reaching 150 total hours TIS, whichever is first; Group 1 engines without detected metal must replace the pin at the next cylinder removal maintenance event or at the next overhaul not to exceed the overhaul interval in Lycoming Service Instruction No. 1009BF (dated July 20, 2026).
Ban on installing affected piston pins
Starting November 24, 2026, you may not install a piston pin defined as 'affected' (P/N LW-13445 manufactured January 7, 2021–December 15, 2025, or with unknown manufacture date) on any engine. The AD explicitly prohibits installation of those affected piston pins after the effective date.
Special flight permits limited by inspection results
Special flight permits may be issued to ferry aircraft for replacement work only if no metal particulates are found during the inspection required by the AD. For Group 2 engines not subject to the 5-hour inspection, an oil change showing no metal particulates is required before issuing a special flight permit. Special flight permits are not allowed to postpone performing the visual inspection itself.
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