- Date
- July 21, 1992, 17:45 local (23:45 UTC)
- Place
- Denver, CO
- Injuries
- 26 uninjured
- Damage
- No damage
- Phase of flight
- Approach
- Aircraft
- N221YVEmbraer EMB-120 RT
- Weather
- Visual (VMC) · Day
- Status
- Completed · report May 26, 1993
- Report
- Approved by Office Director
- FAA report
- 19920721037959I
- Case key
- 18173
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the incident.
On this page
Probable cause
Open air ground circuit breakers that allowed the propellers to overspeed. A factor was: clear air turbulence.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
The captain was flying the airplane with his right hand resting on the power controls. As the airplane turned onto final approach, it encountered turbulence of sufficient intensity that the captain's feet came off the rudder pedals. He felt a 'click' in his hand and 'there was an instantaneous propeller overspeed.' The engine was eventually secured by closing the fuel shutoff valve and an uneventful no flap landing was made. Post incident examination disclosed both air ground circuit breakers were open. The left engine was found to be functionally destroyed. A readout of the digital flight data recorder disclosed the maximum left and right propeller RPM values attained were 150.49% and 120.4%, respectively. Vertical acceleration values ranged from .647 to 1.26 g's, and longitudinal acceleration values ranged from .037 to .096 g's. the right engine torque peaked at 37%, while the left engine torque remained at 0%. Right engine fuel flow was 16% to 19% lower than left engine fuel flow, and propeller imbalance values for the left engine was approximately 50% higher than those recorded for the right engine.
Aircraft
- Registration
- N221YV
- Reported as
- Embraer EMB-120 RT
- Category
- Airplane
- Serial number
- 120.221
- Airframe hours
- 3,928
- Engine
- P&W PW-118A, 1,273 horsepower, turbo prop
- Damage
- No damage
- Flight
- Part 135
- Operator
- Mesa Airlines, Inc., doing business as United Express
- Registered owner
- Chemical Trust Company Of Ca
- Airworthiness certificate
- Standard, Transport
- Last inspection
- Continuous airworthiness · July 20, 1992 · 7 hours before
- Departed
- DRO · Durango, CO
- Destination
- DEN
- Flight plan
- IFR
- Airport
- DEN · Stapleton International, runway 26, 8,599 × 150 ft, concrete
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 34
- Certificates
- Airline transport, Flight instructor, Commercial
- Airplane ratings
- Single-engine land, Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Class 1, Valid Medical--no waivers/lim.
- Seat
- Left
- Flight hours
- 6,950 total · 179 in this make and model · 5,920 as pilot in command · 190 in the last 90 days · 100 in the last 30 days · 5 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 20° at 6 knots
- Visibility
- 40 statute miles
- Lowest ceiling
- None
- Temperature
- 84 °F, dew point 54 °F
- Altimeter
- 29.00 inHg
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.