What is the consequence if blade tip clearance is out of tolerance after reassembly?

• A. Increased efficiency.
• B. No effect.
• C. Reduced stability.
• D. Causes rubs, reduced efficiency, increased vibration risk, and accelerated wear.

Answer: (C)

Blade tip clearance sets the gap between the blade tips and the shroud, and it must stay within specified limits to avoid contact. If this clearance is out of tolerance after reassembly, the blade tips can rub against the shroud during rotation. That rubbing introduces aerodynamic losses, which reduces efficiency, and it excites the rotor, raising vibration risk. It also accelerates wear on both the blade tips and the shroud, potentially leading to further damage. Together, these effects are the most complete description of the consequence: rubs, reduced efficiency, increased vibration risk, and accelerated wear. Increased efficiency would not occur; no effect isn’t accurate; and reduced stability describes a symptom but doesn’t capture the full, direct impact of rubbing and wear.