What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
On 21 August 2019 at 11:50 am PDT, aircraft N4237N, a Cessna 120, was involved in an off field landing/crash off the departure end of Livermore municipal airports runway 25L. privacy data omitted, Was the sole person and pilot at the time of the event. She reports that when she powered up and gained speed down the runway, she could feel the aircraft was taking longer than usual to come up to speed. The airspeed was not determined but the aircraft become airbourn and climbe to 50 to 100 feet above ground level, then it stopped climbing. The pilot vered left and shortly after impacted the ground. The pilot sustained injuries to her arm and was taken for medical treatment and later released that day.
June 2, 2021- inspected airframe and powerplant in storage yard at Livermore municipal airport (lvk). The aircraft was found stored in an open yard without cover. Aircraft engine was placed on the ground under the left wing. The engine had the propeller installed. The engine was pointing upward at about 45 degrees and leaned over the right (pilot?s perspective) at about 30 degrees.
June 9, 2021 - inspected aircraft engine with assistance of NTSB provided maintenance shop and technician. The engine was moved to the hanger from the storage yard. First, the sparkplugs were removed and inspected. The #4 cylinder had both spark plugs oil fouled. The #3 lower spark plug was found oil fouled as well. These three spark plugs had oil and soot bridging the gap between the electrodes. All other spark plugs had black soot build-up on the electrodes and insulator. Verified ignition timing to engine and found it to be at the required 24 degrees before top center, plus or minus two degrees. Removed the propeller. Installed the engine on engine stand. Inspected the ignition hardness and found it to be damaged from the accident. Removed and inspected magnetos. Disassembled each magneto, inspected points, internal condition. Removed and cut open oil filter. Inspected oil filter and found it contained very clean oil and no particulates in the filter element. Checked all cylinders to ensure they made compression. Removed valve covers of all cylinders and inspected valve actuation. Visually inspected cylinder through spark plug holes. Removed and inspected carburetor. Found accelerator pump to be frozen from rust and kept the throttle from being operated. Inspected carburetor jets, mixture valve, float and float needle and seat. Inspected both exhaust muffler assemblies for blockages.
Only points of interest from the inspection were with the spark plugs and the carburetor accelerator pump. With both the upper and lower spark plugs in the #4 cylinder fouled there is no source of ignition in that cylinder. Thus, reducing the power output of the engine to only three of the four cylinders. This is consistent with reports about the performance of the engine prior to the accident. Also noted was the carburetor accelerator pump was found frozen. This made it so the throttle arm could not be actuated without disengaging the linkage to the accelerator pump. The shaft of the accelerator pump that is exposed to the environment was found rusted and the plating flaking up. The engine being stored exposed to the environment is a major factor to this condition.
As the FAA filed it
ON 21 AUGUST 2019 AT 11:50 AM PDT, AIRCRAFT N4237N, A CESSNA 120, WAS INVOLVED IN AN OFF FIELD LANDING/CRASH OFF THE DEPARTURE END OF LIVERMORE MUNICIPAL AIRPORTS RUNWAY 25L. ^PRIVACY DATA OMITTED^, WAS THE SOLE PERSON AND PILOT AT THE TIME OF THE EVENT. SHE REPORTS THAT WHEN SHE POWERED UP AND GAINED SPEED DOWN THE RUNWAY, SHE COULD FEEL THE AIRCRAFT WAS TAKING LONGER THAN USUAL TO COME UP TO SPEED. THE AIRSPEED WAS NOT DETERMINED BUT THE AIRCRAFT BECOME AIRBOURN AND CLIMBE TO 50 TO 100 FEET ABOVE GROUND LEVEL, THEN IT STOPPED CLIMBING. THE PILOT VERED LEFT AND SHORTLY AFTER IMPACTED THE GROUND. THE PILOT SUSTAINED INJURIES TO HER ARM AND WAS TAKEN FOR MEDICAL TREATMENT AND LATER RELEASED THAT DAY.
JUNE 2, 2021- INSPECTED AIRFRAME AND POWERPLANT IN STORAGE YARD AT LIVERMORE MUNICIPAL AIRPORT (LVK). THE AIRCRAFT WAS FOUND STORED IN AN OPEN YARD WITHOUT COVER. AIRCRAFT ENGINE WAS PLACED ON THE GROUND UNDER THE LEFT WING. THE ENGINE HAD THE PROPELLER INSTALLED. THE ENGINE WAS POINTING UPWARD AT ABOUT 45 DEGREES AND LEANED OVER THE RIGHT (PILOT?S PERSPECTIVE) AT ABOUT 30 DEGREES.
JUNE 9, 2021 - INSPECTED AIRCRAFT ENGINE WITH ASSISTANCE OF NTSB PROVIDED MAINTENANCE SHOP AND TECHNICIAN. THE ENGINE WAS MOVED TO THE HANGER FROM THE STORAGE YARD. FIRST, THE SPARKPLUGS WERE REMOVED AND INSPECTED. THE #4 CYLINDER HAD BOTH SPARK PLUGS OIL FOULED. THE #3 LOWER SPARK PLUG WAS FOUND OIL FOULED AS WELL. THESE THREE SPARK PLUGS HAD OIL AND SOOT BRIDGING THE GAP BETWEEN THE ELECTRODES. ALL OTHER SPARK PLUGS HAD BLACK SOOT BUILD-UP ON THE ELECTRODES AND INSULATOR. VERIFIED IGNITION TIMING TO ENGINE AND FOUND IT TO BE AT THE REQUIRED 24 DEGREES BEFORE TOP CENTER, PLUS OR MINUS TWO DEGREES. REMOVED THE PROPELLER. INSTALLED THE ENGINE ON ENGINE STAND. INSPECTED THE IGNITION HARDNESS AND FOUND IT TO BE DAMAGED FROM THE ACCIDENT. REMOVED AND INSPECTED MAGNETOS. DISASSEMBLED EACH MAGNETO, INSPECTED POINTS, INTERNAL CONDITION. REMOVED AND CUT OPEN OIL FILTER. INSPECTED OIL FILTER AND FOUND IT CONTAINED VERY CLEAN OIL AND NO PARTICULATES IN THE FILTER ELEMENT. CHECKED ALL CYLINDERS TO ENSURE THEY MADE COMPRESSION. REMOVED VALVE COVERS OF ALL CYLINDERS AND INSPECTED VALVE ACTUATION. VISUALLY INSPECTED CYLINDER THROUGH SPARK PLUG HOLES. REMOVED AND INSPECTED CARBURETOR. FOUND ACCELERATOR PUMP TO BE FROZEN FROM RUST AND KEPT THE THROTTLE FROM BEING OPERATED. INSPECTED CARBURETOR JETS, MIXTURE VALVE, FLOAT AND FLOAT NEEDLE AND SEAT. INSPECTED BOTH EXHAUST MUFFLER ASSEMBLIES FOR BLOCKAGES.
ONLY POINTS OF INTEREST FROM THE INSPECTION WERE WITH THE SPARK PLUGS AND THE CARBURETOR ACCELERATOR PUMP. WITH BOTH THE UPPER AND LOWER SPARK PLUGS IN THE #4 CYLINDER FOULED THERE IS NO SOURCE OF IGNITION IN THAT CYLINDER. THUS, REDUCING THE POWER OUTPUT OF THE ENGINE TO ONLY THREE OF THE FOUR CYLINDERS. THIS IS CONSISTENT WITH REPORTS ABOUT THE PERFORMANCE OF THE ENGINE PRIOR TO THE ACCIDENT. ALSO NOTED WAS THE CARBURETOR ACCELERATOR PUMP WAS FOUND FROZEN. THIS MADE IT SO THE THROTTLE ARM COULD NOT BE ACTUATED WITHOUT DISENGAGING THE LINKAGE TO THE ACCELERATOR PUMP. THE SHAFT OF THE ACCELERATOR PUMP THAT IS EXPOSED TO THE ENVIRONMENT WAS FOUND RUSTED AND THE PLATING FLAKING UP. THE ENGINE BEING STORED EXPOSED TO THE ENVIRONMENT IS A MAJOR FACTOR TO THIS CONDITION.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.