With propellers removed or secured as the manufacturer directs, what does slowly turning each motor by hand reveal?

• A.The maximum speed the motor will reach in flight
• B.The remaining life of the battery installed
• C.Whether rotation is smooth and free, or shows looseness, roughness, or obstruction needing attention

Why

A hand rotation check is a simple way to feel for bearing wear, bent shafts, or debris before they cause a failure. Roughness or play found this way should be resolved before flight.

Source: FAA-G-8082-22 Ch. 12 · ACS knowledge area: Maintenance and Preflight Inspection Procedures · From the Maintenance & Preflight Inspection practice bank (MNT-052).

Practice this category as a full test

More Motor Rotation Check questions

• During a preflight inspection you find a small nick and a hairline crack near the hub of one propeller. What is the correct action?
• What should a careful inspection of the airframe and arms look for before flight?
• When you rotate a motor by hand during preflight, it feels gritty and makes a scraping sound unlike the other motors. What should you do?
• Under 14 CFR 107.15, when may a remote pilot in command operate a small unmanned aircraft that he or she knows is not in a condition for safe operation?
• How does required maintenance for a small unmanned aircraft differ from that for most manned aircraft?