Maximum airspeed for windshield wiper operation or when the wiper has failed and is not parked?

• A. 200 KIAS
• B. 250 KIAS
• C. 300 KIAS
• D. 350 KIAS

Answer: (B)

Windshield wipers are limited by the wind loads they experience as speed increases. The air pressure on the blade, its linkage, and the motor grows with airspeed, which can cause flutter, excessive wear, or even detachment of the blade, and can stress the windshield and its seals. To prevent damage and ensure reliable operation, there is a certified maximum airspeed for wiper use. When the wipers are operating or when a wiper has failed and isn’t parked, that limit is 250 knots indicated airspeed. Staying below this keeps the wiper motion within safe, predictable limits and avoids over-stressing the system.