NTSB Safety Alert – Aluminum Propeller Blades: Prevent Fractures with Proper Inspections and Maintenance

Aluminum propeller blades can be susceptible to fatigue, cracking, and fracture if a small nick, pit, or corrosion on the surface or edge is not found and repaired during preflight inspection or maintenance. Such damage can concentrate stress from normal airplane operation loads, resulting in fatigue crack initiation and growth followed by propeller blade fracture. Aluminum is more commonly used for airplane propeller blades than composite propeller blades or wood.

Fatigue cracking and fracture of a propeller blade can damage the airframe, and engine, and cause a possible loss of control.

Airplanes utilized for aerial application and coastal operations, as well as those operating on unimproved airstrips, are particularly vulnerable to propeller blade damage. Exposure to chemicals, salt-laden moisture, and loose rocks or debris significantly increases the risk of nicking, corrosion, and fatigue cracking, potentially leading to propeller blade fracture.

Any airplane operating on an unimproved or backcountry airstrip is also at high risk for propeller blade damage because loose rocks, gravel, or debris on unimproved airstrips can create small nicks on aluminum propeller blades that can turn into large fatigue cracks.

Failure to strictly adhere to the manufacturer-recommended overhaul schedules for aluminum propeller blades can have severe consequences. It can lead to the development of undetected fatigue cracks, which, if left unaddressed, can result in dangerous blade separation.

The full NTSB Safety Alert with related accidents/incidents and resources can be accessed here.

For More Information:

Visit the National Transportation Safety Board