Accident Number: WPR14LA153
Date & Time: 03/05/2014, 1930 PST
Registration: N285AM
Aircraft: ZENAIR CH2T
Aircraft Damage: Substantial
Defining Event: Loss of engine power (partial)
Injuries: 2 None
Flight Conducted Under: Part 91: General Aviation - Instructional
Analysis
The flight instructor reported that the airplane entered clouds as it was descending during the training instrument approach. The flight instructor suggested that the student pilot increase the descent rate to pass through the clouds more quickly. After about 1 to 2 minutes in the clouds, the student reduced the engine power and pitched the airplane slightly down to increase the descent rate. Immediately thereafter, the engine speed dropped to between 800 and 1,000 rpm, and the propeller sounded as if it were windmilling. The flight instructor took control of the airplane and completed a mental emergency checklist with the student confirming the steps, which included applying carburetor heat; however, the instructor’s attempts to restore engine power were unsuccessful. The airplane exited the cloud layer between 1,500 and 2,500 ft. The flight instructor declared a Mayday with approach control as he and the student completed the emergency checklist again with no results. The flight instructor initiated an off-airport landing, and, during the landing roll, the airplane collided with trees.
A postaccident examination of the airframe and engine revealed no anomalies that would have precluded normal operation. The weather conditions encountered at the time of the accident were conducive to the formation of serious carburetor icing at cruise power. It is likely that carburetor ice formed during the descent and that the extended low-power setting prevented the engine temperature from getting high enough to melt the ice.
Probable Cause and Findings
The National Transportation Safety Board determines the probable cause(s) of this accident to be:
A total loss of engine power during approach due to carburetor icing, which resulted in an off-airport landing into trees.
Findings
Environmental issues
Conducive to carburetor icing - Effect on equipment (Cause)
Tree(s) - Contributed to outcome
Factual Information
On March 5, 2014, about 1930 Pacific standard time, a Zenair CH2T, N285AM, made an off airport forced landing near Woodland, California. Sierra Academy of Aeronautics was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The flight instructor and the student pilot were not injured. The airplane sustained substantial damage during the accident sequence. The cross-country instructional flight departed Merced (MER), California, with a planned destination of Yolo County Airport (DWA), Woodland. Visual (VMC) meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan had been filed.
Postcrash examination determined that both wing spars had been damaged, and the incident was upgraded to an accident on April 2, 2014.
The flight instructor reported that the flight was for IFR training. The flight instructor and student completed one leg culminating in an instrument approach to Willows, California. The flight instructor stated that, at 1-2 minute intervals during 10-15 minutes of the flight, the engine rpm dropped about 100 revolutions per minute (rpm) audibly and visually on the tachometer during the flight. The airplane was in level cruise flight at 4,000 feet mean sea level (msl). The drop never exceeded 100 rpm; application of carburetor heat, a magneto check, and adjustment to the mixture and throttle settings had no effect. After 15 minutes, the anomaly ceased to occur. The student completed an approach, executed the missed approach, and proceeded on course to Woodland.
The flight instructor reported that he and the student were en route to GHEER intersection on the RNAV 16 approach to Yolo County Airport. Approximately 20 miles from the airport, the student switched fuel tanks as scheduled (every 30 minutes) in accordance with the Sierra Academy checklist. They were cleared to descend to 3,000 feet to cross the GHEER intersection at or above 3,000 feet. With some distance to cover, the flight instructor suggested a descent rate of 200-300 feet per minute (fpm). The student reduced power, and completed the approach checklist, which the flight instructor verified. About 12 miles from GHEER, the airplane entered IFR conditions (a stratus cloud). As the airplane entered the clouds, the flight instructor suggested a higher descent rate to pass through the clouds more quickly.
After 1-2 minutes in the clouds, the student pilot reduced power, and pitched slightly down to increase the descent rate. Nearly at the moment of the reduced power, the engine rpm dropped to 800-1,000 rpm, and the propeller sounded as if it were windmilling. The flight instructor asked the student why he cut the power completely, and the student replied that he had not. The flight instructor stated verbally full power, but the rpm did not change. The flight instructor took control of the airplane, and tried to troubleshoot as he completed a mental emergency checklist (carburetor heat, fuel selector-mixture-fuel pump combinations, fuel gauge, throttle pumping, magneto check, starter check, engine instruments crosscheck). The student confirmed all steps using the emergency checklist. The attempts to restore power were unsuccessful, and the airplane exited the cloud layer between 1,500 to 2,500 feet. The flight instructor declared a Mayday with approach control, as he and the student completed the emergency checklist again with no results.
The crew resigned themselves to an off airport forced landing. The flight instructor had the student pilot call out airspeed and altitude while focusing on a landing point. During 300 feet of the descent, the airplane began shaking violently; the airspeed indicated 60 knots, and there was no stall horn. The shaking stopped about 300 feet above ground level (agl). About 200 feet agl, the landing lights illuminated a power line, and the flight instructor determined that the airplane would stall if he attempted to climb over it. The flight instructor had the student grab a flight bag as a cushion, and turned the fuel selector off. At this point, the flight instructor flew under the power line, and landed just beyond it. The airplane touched down smoothly, and the flight instructor held the nose wheel off the ground as long as possible. A line of small tress came into view, and the flight instructor began to let the nose drop. The nose drop coincided with the wings hitting the trees.
After the airplane came to rest, the flight instructor and student thought that they turned off the rest of the power sources, and exited toward the rear of the airplane. They observed that the fuel tanks appeared undamaged, there was no smell of fuel, and the airplane seemed secure. After waiting a few minutes, they approached the airplane in order to use the radio to call for assistance. They discovered that the avionics master switch was still on. Unable to establish contact with the radio, the flight instructor used his cell phone to contact air traffic control, and provided them with the site's GPS location. About 1.5 hours later, a helicopter spotted them, and directed emergency crews to them.
Examination
A Federal Aviation Administration (FAA) inspector oversaw an examination of the wreckage at the operator's facility. The left and right fuel tanks contained 5 and 6 gallons of fuel, respectively. The gascolator contained a few ounces. The fuel selector valve was in the OFF position. The oil level was 5.5 quarts. The throttle, mixture, and carburetor heat cables were intact, and operated properly. One propeller blade was bent; the other was undamaged. The engine could not be run; a cold compression check resulted in all cylinders testing at or above 68/80 psi.
Carburetor Ice
The conditions encountered in this accident (ambient temperature 61 degrees / dew point 55 degrees Fahrenheit, 82 percent relative humidity), were in the area of serious icing at cruise power.
The FAA's Handbook of Aeronautical Knowledge Chapter 6 discussed carburetor icing. It stated that whenever the throttle was closed during flight, the engine cooled rapidly, and vaporization of the fuel was less complete than if the engine was warm. In this condition, the engine was more susceptible to carburetor icing. It stated that application of carburetor heat would cause a further reduction in power, and possibly engine roughness as melted ice went through the engine. It stated that these symptoms could last from 30 seconds to several minutes, depending on the severity of the icing. It recommended opening the throttle periodically for a few seconds to keep the engine warm; otherwise, the carburetor heat may not provide enough heat to prevent icing.
Airplane Flight Manual
The approach (pre landing) checklist in the airplane's flight manual specified that the carburetor heat should be in the ON position. It did not contain any guidance on periodically adjusting power during extended low throttle operation.
History of Flight
Approach-IFR initial approach
Loss of engine power (partial) (Defining event)
Emergency descent
Off-field or emergency landing
Flight Instructor Information
Certificate: Flight Instructor; Commercial; Private
Age:22
Airplane Rating(s): Multi-engine Land; Single-engine Land
Seat Occupied: Right
Other Aircraft Rating(s): None
Restraint Used:
Instrument Rating(s): Airplane
Second Pilot Present: Yes
Instructor Rating(s): Airplane Multi-engine; Airplane Single-engine; Instrument Airplane
Toxicology Performed: No
Medical Certification: Class 1 Without Waivers/Limitations
Last FAA Medical Exam:
Occupational Pilot: Yes
Last Flight Review or Equivalent:
Flight Time: 522 hours (Total, all aircraft), 132 hours (Total, this make and model), 409 hours (Pilot In Command, all aircraft), 245 hours (Last 90 days, all aircraft), 83 hours (Last 30 days, all aircraft), 7 hours (Last 24 hours, all aircraft)
Student Pilot Information
Certificate:
Age:
Airplane Rating(s):
Seat Occupied: Left
Other Aircraft Rating(s):
Restraint Used:
Instrument Rating(s):
Second Pilot Present: Yes
Instructor Rating(s):
Toxicology Performed:
Medical Certification:
Last FAA Medical Exam:
Occupational Pilot:No
Last Flight Review or Equivalent:
Flight Time:
Aircraft and Owner/Operator Information
Aircraft Make: ZENAIR
Registration: N285AM
Model/Series:CH2T
Aircraft Category: Airplane
Year of Manufacture:
Amateur Built: No
Airworthiness Certificate: Normal
Serial Number: 20-1046
Landing Gear Type: Tricycle
Seats: 2
Date/Type of Last Inspection: 100 Hour
Certified Max Gross Wt.:
Time Since Last Inspection:
Engines: 1 Reciprocating
Airframe Total Time:
Engine Manufacturer: Lycoming
ELT: Installed, activated
Engine Model/Series: O-235-O2C
Registered Owner: KS Aviation
Rated Power: 110 hp
Operator: KS Aviation
Operating Certificate(s) Held: None
Meteorological Information and Flight Plan
Conditions at Accident Site: Visual Conditions
Condition of Light: Night/Dark
Observation Facility, Elevation: KEDU, 100 ft msl
Distance from Accident Site: 8 Nautical Miles
Observation Time: 1915 PST
Direction from Accident Site: 72°
Lowest Cloud Condition:
Visibility: 10 Miles
Lowest Ceiling: Overcast / 3700 ft agl
Visibility (RVR):
Wind Speed/Gusts: 7 knots /
Turbulence Type Forecast/Actual: / None
Wind Direction: 210°
Turbulence Severity Forecast/Actual:
Altimeter Setting: 29.99 inches Hg
Temperature/Dew Point: 16°C / 13°C
Precipitation and Obscuration: No Obscuration; No Precipitation
Departure Point: Merced, CA (MER)
Type of Flight Plan Filed:IFR
Destination: Woodland, CA (DWA)
Type of Clearance: IFR
Departure Time:
Type of Airspace:
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: 38.566667, -121.850000 (est)
YOLO COUNTY- A small fixed-wing plane went down in Dunnigan, Calif. in Yolo County Wednesday night.
The Yolo County Sheriff's Department said deputies and fire personnel pulled the pilot and his passenger out of the plane after finding it in a field near Road 7 and County Road 99W. The pilot had contacted Travis Air Force Base to say that he was not injured; the passenger had a black eye.
Both occupants did not want any medical care and did not need to be treated at the hospital.
"It was a very surprising outcome," Yolo County Sheriff's Deputy Ryan Mez said. "It's pretty surprising you've got a plane crash and they're able to walk away on their own two feet."
The sheriff's department said the two occupants had taken off from Watts Woodland Airport. The pilot reported that the plane was having trouble and going down shortly before 8 p.m. According to Lt. Martin Torres of the Yolo County Sheriff's department, the loss of power to the plane caused it to go down. The FAA is investigating.
Officials searched for the plane in West Sacramento, Woodland and Davis before it was located by a California Highway Patrol helicopter in Dunnigan, which is north of Woodland along Interstate 5.
YOLO COUNTY, Calif. (KCRA) —Rescue crews on Wednesday night found a plane that had been missing for about an hour after officials at Travis Air Force Base received a mayday call.
At 7:28 p.m., the base took a call from a small fixed-wing aircraft, according to the California Highway Patrol.
Shortly after, the base lost radio contact and lost the plane on the radar. Its last known location was somewhere in Yolo County, the CHP said.
But before the aircraft went off-radar, its pilot did relay some GPS coordinates on its location.
When crews uploaded the coordinates, they came back to a location in West Sacramento.
But officials went out and were unable to find the plane, the CHP said.
Finally, an observant CHP chopper pilot noticed the coordinates were aviation coordinates -- and pinpointed the aircraft in Dunnigan. The plane went down near County Road 7 and County Road 99W.
The aircraft lost power, so the pilot had to make an emergency landing in a field.
One passenger was on board at the time, but no one was hurt.
Two people are reported safe after their plane made an emergency landing this evening in a field near Dunnigan.
Lt. Martin Torres of the Yolo County Sheriff’s Department said a call was received at 7:28 pm. from Travis Air Force Base reporting that a small plane had made an emergency call. The plane was reported to be about 12 miles northwest of Watts Woodland Airport, a small private airport near Woodland. Travis reported that the plane had disappeared from radar but provided coordinates for the location it was believed to have gone down.
The coordinates put the site near West Sacramento and a search was launched, but when a California Highway Patrol air crew joined in the search, they recognized the coordinates as aviation coordinates, not GPS coordinates, which are different, Torres said. That shifted the search to the Dunnigan area, where the small fixed-wing aircraft was found at 8:41 p.m., he said.
An emergency medical service crew was dispatched to the scene and reported that the pilot and a passenger were uninjured, although one may end up with a black eye, Torres said. No information was available on where the pilot and passenger were from or where they were going.
