Service Bulletin No. 533 D

DATE:

February 10, 2026

MODELS AFFECTED:

All Lycoming reciprocating aircraft engines

TIME OF COMPLIANCE:

BEFORE FURTHER FLIGHT

REASON FOR REVISION

Added an item to the “A propeller strike includes:” section. Added a new NOTICE in the “Recommended Corrective Action for Propeller Strikes”
section. Changed 17-grit to 150-grit in both checklists.
 

In the checklist for All Engines - Except Geared Engines:
• Revised Steps 6 and 27 to specify which oil sumps must be blast cleaned and be inspected with Fluorescent Penetrant Inspection.
• Revised Step 31 and added new Step 32, to create separate inspection steps for tappets and lifters.
 

In the checklist for Geared Engines:
• Revised Step 32 and added new Step 33, to create separate inspection steps for tappets and lifters.