Saturday, September 05, 2020

Loss of Engine Power (Partial): Cessna 140A, N140AB; accident occurred July 18, 2020 at Arlington Municipal Airport (KGKY), Tarrant County, Texas

Supplied image of the right-side fuselage. 
The fuselage exhibits wrinkle deformation.

Carb Icing Chart.

Aviation Accident Factual Report - National Transportation Safety Board

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity:

Federal Aviation Administration / Flight Standards District Office; Irving, Texas

Investigation Docket - National Transportation Safety Board:

Location: Arlington, TX
Accident Number: CEN20LA291
Date & Time: 07/18/2020, 0745 CDT
Aircraft:CESSNA 140 
Aircraft Damage: Substantial
Defining Event: Loss of engine power (partial)
Injuries: 2 None
Flight Conducted Under: Part 91: General Aviation - Instructional 

On July 18, 2020, about 0745 central daylight time, a Cessna 140 airplane, N140AB, was substantially damaged when it was involved in an accident near Arlington, Texas. The flight instructor and student pilot were uninjured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.

The flight instructor reported the purpose of the flight was to fly the airplane cross-country for tire repairs, and at the same time, train the student pilot in the airplane. The student pilot started the engine about 0715. The recorded weather indicated the temperature was 79° F and the dew point was 73° F. The flight instructor mentioned that since the outside air temperature was close to the dew point, they would have to be careful and cautious about carburetor icing, even if there was no visible moisture in the air.

The flight instructor related a previous occurrence when he flew this airplane for the first time with another instructor. Then, the condition was almost 100% relative humidity and the carburetor heat was kept on about "10%" during the flight when at cruise power setting, and full carburetor heat at lower than cruise power. However, a rough engine or any sign of carburetor ice was not encountered during that flight.

During the accident flight, the airplane's engine performed as expected during the run up. The student pilot set the carburetor heat on cold for takeoff and departed without issues. The flaps were retracted and the airplane was accelerated to best climb airspeed. The rate of climb was about 250 ft per minute and the engine was running at full power.

About two minutes into the flight, the engine started to run a "little bit rough and shaky." The instructor pulled the carburetor heat on about 10% hot and left it in this position in accordance with his training for this airplane. The engine roughness disappeared, and the airplane kept climbing at the same rate.

About one minute later, the roughness came back, more severe this time. The instructor pulled the carburetor heat all the way on to full hot and waited. The roughness continued and the power available was not allowing the airplane to continue the climb at the same rate.

The airplane's pitch attitude was progressively lowered to maintain the airspeed, and full power was not sufficient to keep the airplane in a level flight attitude at 1,200 ft. There was no suitable area ahead for about the next 8 to 10 miles to perform an off-field emergency landing, so the instructor elected to turn back to the departure airport. He was not confident that the airplane could maintain altitude in the traffic pattern, so he elected to land on a closer runway with a quartering tailwind. During the landing roll, as the airplane slowed down, he retracted the flaps to remove any residual lift and applied the yoke "slightly diving" away from the wind. While the airplane was still moving forward at a low ground speed, the nose "suddenly" yawed very "quickly and strongly" to the right. The instructor pilot applied ailerons, elevators, and full left rudder and brake, but these did not stop the yaw. The airplane subsequently ground looped and came to rest in the grass resulting in substantial damage to the aft fuselage and tailwheel.

Using the pilot's reported departure weather, the plotted relative humidity at this temperature and dew point spread was about 80%. A review of the icing probability chart contained in Federal Aviation Administration Special Airworthiness Information Bulletin CE-09-35 revealed that the weather conditions at the time of the accident were "conducive to serious icing at glide power."

The operator of the airplane was asked to run the engine after the accident. The engine started and operated "normally." 

Flight Instructor Information

Certificate: Flight Instructor; Commercial
Age: 40, Male
Airplane Rating(s): Multi-engine Land; Single-engine Land; Single-engine Sea
Seat Occupied: Right
Other Aircraft Rating(s): None
Restraint Used:
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): Airplane Single-engine
Toxicology Performed: No
Medical Certification:  Class 2 With Waivers/Limitations
Last FAA Medical Exam: 07/06/2020
Occupational Pilot:Yes 
Last Flight Review or Equivalent: 03/25/2020
Flight Time:  1314 hours (Total, all aircraft), 3.5 hours (Total, this make and model), 978 hours (Pilot In Command, all aircraft), 49 hours (Last 90 days, all aircraft), 18 hours (Last 30 days, all aircraft), 1.3 hours (Last 24 hours, all aircraft)

Student Pilot Information

Certificate: Student
Age: 45, Female
Airplane Rating(s): None
Seat Occupied:Left 
Other Aircraft Rating(s): None
Restraint Used:
Instrument Rating(s): None
Second Pilot Present: Yes
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 3 Without Waivers/Limitations
Last FAA Medical Exam: 12/13/2019
Occupational Pilot: No
Last Flight Review or Equivalent:
Flight Time:  159 hours (Total, all aircraft), 17 hours (Total, this make and model), 17 hours (Pilot In Command, all aircraft), 17 hours (Last 90 days, all aircraft), 8 hours (Last 30 days, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Make: CESSNA
Registration: N140AB
Model/Series: 140 A
Aircraft Category: Airplane
Year of Manufacture: 1951
Amateur Built: No
Airworthiness Certificate: Utility
Serial Number: 15703
Landing Gear Type: Tailwheel
Seats: 2
Date/Type of Last Inspection: 01/14/2020, Annual
Certified Max Gross Wt.: 1500 lbs
Time Since Last Inspection:
Engines: 1 Reciprocating
Airframe Total Time: 10434 Hours at time of accident
Engine Manufacturer: Continental
ELT: C91 installed, not activated
Engine Model/Series: O-200A
Registered Owner: On file
Rated Power: 100 hp
Operator:On file 
Operating Certificate(s) Held: None

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual Conditions
Condition of Light: Day
Observation Facility, Elevation: KGKY, 630 ft msl
Distance from Accident Site: 0 Nautical Miles
Observation Time:0653 CDT 
Direction from Accident Site: 52°
Lowest Cloud Condition: Clear
Visibility:  10 Miles
Lowest Ceiling: None
Visibility (RVR):
Wind Speed/Gusts: 6 knots /
Turbulence Type Forecast/Actual:
Wind Direction: 150°
Turbulence Severity Forecast/Actual:
Altimeter Setting: 30.03 inches Hg
Temperature/Dew Point: 26°C / 23°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point:Arlington, TX (GKY) 
Type of Flight Plan Filed: None
Destination: Fort Worth, TX (FWS)
Type of Clearance: VFR
Departure Time: 0730 CDT
Type of Airspace: Class D 

Airport Information

Runway Surface Type: Concrete
Airport Elevation: 628 ft
Runway Surface Condition: Dry
Runway Used: 34
IFR Approach: None
Runway Length/Width: 6080 ft / 100 ft
VFR Approach/Landing: Forced Landing 

Wreckage and Impact Information

Crew Injuries: 2 None
Aircraft Damage: Substantial
Passenger Injuries: N/A
Aircraft Fire:None 
Ground Injuries:N/A 
Aircraft Explosion: None
Total Injuries: 2 None
Latitude, Longitude: 32.663889, -97.094167 (est)

1 comment:

  1. from Dan Thomas "The small Continentals (like those in the Cessna 140 and 150) are famous ice machines. In conditions like those posted, you are guaranteed carb ice at some point before you even take off. It's smart to check for ice again immediately before takeoff if you've taxied a while or been idling after the runup, as it will be making ice in that time. In mine, I will taxi to the takeoff point with the carb heat on just to get it warmed up good for the takeoff, and after the throttle is wide open the ice is much less likely.

    Don't think about percent humidity. Aviation weather uses dewpoint instead, and at high relative humidity the spread between the ambient temperature and dewpoint temperature is small, raising the risk of carb ice. And it can happen at much warmer temperatures, too. Carb ice is one of those things not taught nearly well enough to students, and some pilots, sooner or later, eventually lose an engine to it. It's one of the major causes of engine failure."