Thursday, October 10, 2019

Loss of Engine Power (Partial): Zenith STOL CH701, N701BJ; accident occurred October 05, 2019 in Garden Ridge, Comal County, Texas

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

Additional Participating Entity: 
Federal Aviation Administration / Flight Standards District Office; San Antonio, Texas

Aviation Accident Final Report - National Transportation Safety Board:

Investigation Docket - National Transportation Safety Board:

Location: Garden Ridge, TX
Accident Number: CEN20LA005
Date & Time: 10/05/2019, 1030 CDT
Registration: N701BJ
Aircraft: Zenair ZENITH CH 701
Aircraft Damage: Substantial
Defining Event: Loss of engine power (partial)
Injuries: 2 None
Flight Conducted Under: Part 91: General Aviation - Personal


The pilot reported that the airplane was fully loaded with fuel and that all preflight checks were normal for the personal flight. He indicated that, after departure, as the airplane reached between about 10 and 15 ft above ground level, the engine power rolled back "opposite of a surge." He landed straight ahead into brush past the runway end. During the landing, the right main landing gear and nose landing gear collapsed, and the fuselage sustained substantial damage.

During the engine examination, several items were identified that could have contributed to a reduction or loss of engine power, including a lack of a fuel return line, a loose exhaust pipe, dirty air filters, and a disconnected choke lever. However, an engine test run was conducted without correcting any of the identified deficiencies, and the engine performed without interruption; no anomalies were noted. Further, no anomalies were noted during the airframe examination. Although the conditions were conducive to serious carburetor icing at glide power, the airplane was operating at takeoff power at the time of the accident. The reason for the loss of engine power could not be determined.

Probable Cause and Findings
The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The partial loss of engine power for reasons that could not be determined based on the available evidence. 


Environmental issues
Rough terrain - Contributed to outcome

Not determined
Not determined - Unknown/Not determined (Cause)

Factual Information 

***This report was modified on April 17, 2020. Please see the docket for this accident to view the original report.***

On October 5, 2019, about 1030 central daylight time, a Zenair Zenith CH-701 airplane, N701BJ, impacted terrain near Garden Ridge, Texas, following a partial loss of engine power after takeoff. The private pilot and passenger were not injured. The airplane was substantially damaged. The airplane was registered to the pilot and operated as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed, and the flight which was operating without a flight plan. The flight was originating from Kitty Hawk Flying Field Ultralight Flightpark (TS67), Garden Ridge, Texas, when the accident occurred.

The pilot reported the airplane was fully loaded with fuel, it started normally, and all preflight checks were normal. The airplane reached 10-15 ft above the ground during takeoff when the engine RPM rolled back "opposite of a surge." The pilot pulled the throttle control back to idle and landed straight ahead in an area of brush off the end of the runway. The right main gear and nose gear collapsed, and the fuselage exhibited buckling.

An examination of the engine and airframe was conducted by a representative of Rotech and a Federal Aviation Administration inspector. No anomalies were found during the airframe examination. When first examined, the engine was attached to the engine mount and firewall of the airplane, and the engine cowling was still in place. The retaining nut for the 2/4 cylinder carburetor choke lever was not present and the choke lever was found detached at the control valve. The fuel feed line to the mechanical fuel pump was badly cracked. The carburetor float bowls were removed and inspected. Some debris was found in the 2/4 carburetor; however, the main jet was clear of any obstructions. Examination also found there was no fuel return line installed in the airplane as recommended by the engine manufacturer, the No. 3 cylinder exhaust pipe was loose, and the air filters were dirty.

The damaged propeller was removed from the engine and a new propeller was installed for test run purposes. No other repairs were made to the engine. The engine was turned over with the use of the engine's electric starter. After a few rotations the engine started and ran at idle. The throttle was then advanced to around 3,500 rpm and then to 4,000 RPM. All engine parameters appeared normal after several minutes and the engine was shut down. No anomalies were noted during the engine test run.

The pilot reported at the time of the accident the temperature was 80° F and the dewpoint was 72° F. A review of the Federal Aviation Administration's carburetor icing probability chart indicated that weather conditions at the time of the accident were conducive to serious carburetor icing at glide power. 

History of Flight

Initial climb
Unknown or undetermined
Loss of engine power (partial) (Defining event) 

Pilot Information

Certificate: Private
Age: 37, Male
Airplane Rating(s): Single-engine Land
Seat Occupied: Left
Other Aircraft Rating(s): None
Restraint Used:
Instrument Rating(s): None
Second Pilot Present: No
Instructor Rating(s): None
Toxicology Performed: No
Medical Certification: Class 1 Without Waivers/Limitations
Last FAA Medical Exam: 12/15/2017
Occupational Pilot: No
Last Flight Review or Equivalent:
Flight Time:   188 hours (Total, all aircraft), 136 hours (Total, this make and model), 145 hours (Pilot In Command, all aircraft), 61 hours (Last 90 days, all aircraft), 28 hours (Last 30 days, all aircraft), 0 hours (Last 24 hours, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Make: Zenair
Registration: N701BJ
Model/Series: ZENITH CH 701 No Series
Aircraft Category: Airplane
Year of Manufacture: 2002
Amateur Built: Yes
Airworthiness Certificate: Normal
Serial Number: JN316
Landing Gear Type: Tricycle
Date/Type of Last Inspection: 08/04/2019, Annual
Certified Max Gross Wt.:
Time Since Last Inspection:
Engines:  Reciprocating
Airframe Total Time: 349.2 Hours as of last inspection
Engine Manufacturer: Rotax
ELT: Installed, not activated
Engine Model/Series: 912 UL-S
Registered Owner: On file
Rated Power: 80 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:
Distance from Accident Site:
Observation Time:
Direction from Accident Site:
Lowest Cloud Condition:
Lowest Ceiling:
Visibility (RVR):
Wind Speed/Gusts: Calm /
Turbulence Type Forecast/Actual:
Wind Direction:
Turbulence Severity Forecast/Actual:
Altimeter Setting: 30.03 inches Hg
Temperature/Dew Point: 27°C / 22°C
Precipitation and Obscuration:
Departure Point: Garden Ridge, TX (TS67)
Type of Flight Plan Filed: None
Type of Clearance: None
Departure Time:  CDT
Type of Airspace:

Airport Information

Airport: Kitty Hawk Flying Field (TS67)
Runway Surface Type: Asphalt
Airport Elevation: 860 ft
Runway Surface Condition: Dry
Runway Used: 14
IFR Approach: None
Runway Length/Width: 700 ft / 20 ft
VFR Approach/Landing: Forced Landing

Wreckage and Impact Information

Crew Injuries: 1 None
Aircraft Damage: Substantial
Passenger Injuries: 1 None
Aircraft Fire: None
Ground Injuries: N/A
Aircraft Explosion: None
Total Injuries: 2 None
Latitude, Longitude: 29.621944, -98.277222 (est)

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