Investigation Summary
The accident was the result of two independent factors converging. First, during a 'Detail 6' maintenance check two days prior, a mechanic adjusted the elevator cable tension but skipped nine critical steps of the rigging procedure. This error limited the elevator's downward travel to 7 degrees instead of the required 15 degrees. Second, the airline's weight and balance program used outdated FAA average passenger weights. On the day of the flight, the actual weight of the passengers and baggage put the aircraft's CG at 45.5% MAC, well beyond the 40% certified aft limit. When the pilot attempted to compensate for the natural pitch-up during takeoff, the restricted elevator travel provided insufficient authority to push the nose down.
Final Conclusions
The NTSB determined the probable cause was the loss of pitch control resulting from incorrect rigging of the elevator control system, compounded by an aft center of gravity. Contributing factors included Air Midwest's lack of maintenance oversight, the failure of the quality assurance inspector to detect the rigging error, and the FAA's reliance on inaccurate average weight assumptions for regional aircraft.
Video Analysis
The Mistake That Killed 21 People | Air Midwest Flight 5481 — A detailed look at how maintenance errors and weight miscalculations led to the crash of a Beechcraft 1900D in Charlotte.
Watch on YouTube ↗If playback is blocked, the owner has disabled embedding — use the link above.
Systems & Failure Modes
Elevator Control System
The primary flight control surface for pitch; incorrect rigging of the cables and turnbuckles restricted its range of motion.
Flight Data Recorder (FDR)
An F-1000 recorder was installed; the failure to calibrate its pitch potentiometer during maintenance hid the rigging error.
Weight and Balance Program
The operational system used to calculate aircraft loading, which failed to account for modern average passenger weights.
Interesting Facts
- 01The elevator downward travel was restricted to 7 degrees, roughly half of the 14-15 degrees specified by the manufacturer.
- 02The actual Center of Gravity (CG) was 45.5% MAC, exceeding the 40% aft limit.
- 03The mechanic skipped 9 applicable steps in the Beech 1900D elevator rigging procedure.
- 04The FAA's average passenger weight estimates used at the time were found to be approximately 20 pounds too low per person.
- 05The aircraft was approximately 580 pounds over its maximum takeoff weight.
Safety Actions & Advisories
Revised Weight Standards
The FAA issued new guidance (AC 120-27E) increasing the standard average weights for passengers and carry-on bags.
Maintenance Rigging Procedures
Raytheon Aircraft Company revised the Beech 1900D maintenance manual to clarify that the entire rigging procedure must be followed even for minor adjustments.