What is the maximum positive end of the stab trim range?

• A. +2
• B. -13
• C. 0
• D. +13

Answer: (A)

Stab trim range is how far the horizontal stabilizer trim can move to fine-tune the airplane’s pitch without using the elevator. For the CRJ-550, the trim range is not symmetric: you can move a small amount in the positive direction, but the positive limit is only two degrees. This small positive trim is deliberate to provide just enough adjustment to relieve minor trim forces without risking over-trimming the tail, which could reduce elevator effectiveness or push the aircraft into an unsafe pitch range during takeoff, approach, or other phases of flight. The system allows a much larger negative trim range (up to thirteen degrees) to accommodate nose-down trim needs from forward CG, weight distribution, or other conditions. So the maximum positive end is two degrees because the design restricts positive trim to maintain safe control authority and structural limits.